1 // RUN: %check_clang_tidy %s bugprone-stringview-nullptr -std=c++17 %t
2 
3 namespace std {
4 
5 using size_t = long long;
6 using nullptr_t = decltype(nullptr);
7 
8 template <typename T>
9 T &&declval();
10 
11 template <typename T>
12 struct type_identity { using type = T; };
13 template <typename T>
14 using type_identity_t = typename type_identity<T>::type;
15 
16 template <typename CharT>
17 class basic_string_view {
18 public:
19   constexpr basic_string_view() {}
20 
21   constexpr basic_string_view(const CharT *) {}
22 
23   // Not present in C++17 and C++20:
24   // constexpr basic_string_view(std::nullptr_t) {}
25 
26   constexpr basic_string_view(const CharT *, size_t) {}
27 
28   constexpr basic_string_view(const basic_string_view &) {}
29 
30   constexpr basic_string_view &operator=(const basic_string_view &) {}
31 };
32 
33 template <typename CharT>
34 constexpr bool operator<(basic_string_view<CharT>, basic_string_view<CharT>) {
35   return {};
36 }
37 template <typename CharT>
38 constexpr bool operator<(type_identity_t<basic_string_view<CharT>>,
39                          basic_string_view<CharT>) {
40   return {};
41 }
42 template <typename CharT>
43 constexpr bool operator<(basic_string_view<CharT>,
44                          type_identity_t<basic_string_view<CharT>>) {
45   return {};
46 }
47 
48 template <typename CharT>
49 constexpr bool operator<=(basic_string_view<CharT>, basic_string_view<CharT>) {
50   return {};
51 }
52 template <typename CharT>
53 constexpr bool operator<=(type_identity_t<basic_string_view<CharT>>,
54                           basic_string_view<CharT>) {
55   return {};
56 }
57 template <typename CharT>
58 constexpr bool operator<=(basic_string_view<CharT>,
59                           type_identity_t<basic_string_view<CharT>>) {
60   return {};
61 }
62 
63 template <typename CharT>
64 constexpr bool operator>(basic_string_view<CharT>, basic_string_view<CharT>) {
65   return {};
66 }
67 template <typename CharT>
68 constexpr bool operator>(type_identity_t<basic_string_view<CharT>>,
69                          basic_string_view<CharT>) {
70   return {};
71 }
72 template <typename CharT>
73 constexpr bool operator>(basic_string_view<CharT>,
74                          type_identity_t<basic_string_view<CharT>>) {
75   return {};
76 }
77 
78 template <typename CharT>
79 constexpr bool operator>=(basic_string_view<CharT>, basic_string_view<CharT>) {
80   return {};
81 }
82 template <typename CharT>
83 constexpr bool operator>=(type_identity_t<basic_string_view<CharT>>,
84                           basic_string_view<CharT>) {
85   return {};
86 }
87 template <typename CharT>
88 constexpr bool operator>=(basic_string_view<CharT>,
89                           type_identity_t<basic_string_view<CharT>>) {
90   return {};
91 }
92 
93 template <typename CharT>
94 constexpr bool operator==(basic_string_view<CharT>, basic_string_view<CharT>) {
95   return {};
96 }
97 template <typename CharT>
98 constexpr bool operator==(type_identity_t<basic_string_view<CharT>>,
99                           basic_string_view<CharT>) {
100   return {};
101 }
102 template <typename CharT>
103 constexpr bool operator==(basic_string_view<CharT>,
104                           type_identity_t<basic_string_view<CharT>>) {
105   return {};
106 }
107 
108 template <typename CharT>
109 constexpr bool operator!=(basic_string_view<CharT>, basic_string_view<CharT>) {
110   return {};
111 }
112 template <typename CharT>
113 constexpr bool operator!=(type_identity_t<basic_string_view<CharT>>,
114                           basic_string_view<CharT>) {
115   return {};
116 }
117 template <typename CharT>
118 constexpr bool operator!=(basic_string_view<CharT>,
119                           type_identity_t<basic_string_view<CharT>>) {
120   return {};
121 }
122 
123 using string_view = basic_string_view<char>;
124 
125 } // namespace std
126 
127 using SV = std::string_view; // Used in some places for shorter line length
128 
129 void function(std::string_view);
130 void function(std::string_view, std::string_view);
131 
132 void temporary_construction() /* a */ {
133   // Functional Cast
134   {
135     (void)(std::string_view(nullptr)) /* a1 */;
136     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing basic_string_view from null is undefined; replace with the default constructor
137     // CHECK-FIXES: {{^}}    (void)(std::string_view()) /* a1 */;
138 
139     (void)(std::string_view((nullptr))) /* a2 */;
140     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
141     // CHECK-FIXES: {{^}}    (void)(std::string_view()) /* a2 */;
142 
143     (void)(std::string_view({nullptr})) /* a3 */;
144     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
145     // CHECK-FIXES: {{^}}    (void)(std::string_view()) /* a3 */;
146 
147     (void)(std::string_view({(nullptr)})) /* a4 */;
148     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
149     // CHECK-FIXES: {{^}}    (void)(std::string_view()) /* a4 */;
150 
151     (void)(std::string_view({})) /* a5 */; // Default `const CharT*`
152     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
153     // CHECK-FIXES: {{^}}    (void)(std::string_view()) /* a5 */;
154   }
155 
156   // Temporary Object
157   {
158     (void)(std::string_view{nullptr}) /* a6 */;
159     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
160     // CHECK-FIXES: {{^}}    (void)(std::string_view{}) /* a6 */;
161 
162     (void)(std::string_view{(nullptr)}) /* a7 */;
163     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
164     // CHECK-FIXES: {{^}}    (void)(std::string_view{}) /* a7 */;
165 
166     (void)(std::string_view{{nullptr}}) /* a8 */;
167     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
168     // CHECK-FIXES: {{^}}    (void)(std::string_view{}) /* a8 */;
169 
170     (void)(std::string_view{{(nullptr)}}) /* a9 */;
171     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
172     // CHECK-FIXES: {{^}}    (void)(std::string_view{}) /* a9 */;
173 
174     (void)(std::string_view{{}}) /* a10 */; // Default `const CharT*`
175     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
176     // CHECK-FIXES: {{^}}    (void)(std::string_view{}) /* a10 */;
177   }
178 
179   // C-Style Cast && Compound Literal
180   {
181     (void)((std::string_view) nullptr) /* a11 */;
182     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
183     // CHECK-FIXES: {{^}}    (void)((std::string_view) {}) /* a11 */;
184 
185     (void)((std::string_view)(nullptr)) /* a12 */;
186     // CHECK-MESSAGES: :[[@LINE-1]]:30: warning: constructing{{.*}}default
187     // CHECK-FIXES: {{^}}    (void)((std::string_view){}) /* a12 */;
188 
189     (void)((std::string_view){nullptr}) /* a13 */;
190     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
191     // CHECK-FIXES: {{^}}    (void)((std::string_view){}) /* a13 */;
192 
193     (void)((std::string_view){(nullptr)}) /* a14 */;
194     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
195     // CHECK-FIXES: {{^}}    (void)((std::string_view){}) /* a14 */;
196 
197     (void)((std::string_view){{nullptr}}) /* a15 */;
198     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
199     // CHECK-FIXES: {{^}}    (void)((std::string_view){}) /* a15 */;
200 
201     (void)((std::string_view){{(nullptr)}}) /* a16 */;
202     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
203     // CHECK-FIXES: {{^}}    (void)((std::string_view){}) /* a16 */;
204 
205     (void)((std::string_view){{}}) /* a17 */; // Default `const CharT*`
206     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
207     // CHECK-FIXES: {{^}}    (void)((std::string_view){}) /* a17 */;
208 
209     (void)((const std::string_view) nullptr) /* a18 */;
210     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
211     // CHECK-FIXES: {{^}}    (void)((const std::string_view) {}) /* a18 */;
212 
213     (void)((const std::string_view)(nullptr)) /* a19 */;
214     // CHECK-MESSAGES: :[[@LINE-1]]:36: warning: constructing{{.*}}default
215     // CHECK-FIXES: {{^}}    (void)((const std::string_view){}) /* a19 */;
216 
217     (void)((const std::string_view){nullptr}) /* a20 */;
218     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
219     // CHECK-FIXES: {{^}}    (void)((const std::string_view){}) /* a20 */;
220 
221     (void)((const std::string_view){(nullptr)}) /* a21 */;
222     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
223     // CHECK-FIXES: {{^}}    (void)((const std::string_view){}) /* a21 */;
224 
225     (void)((const std::string_view){{nullptr}}) /* a22 */;
226     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
227     // CHECK-FIXES: {{^}}    (void)((const std::string_view){}) /* a22 */;
228 
229     (void)((const std::string_view){{(nullptr)}}) /* a23 */;
230     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
231     // CHECK-FIXES: {{^}}    (void)((const std::string_view){}) /* a23 */;
232 
233     (void)((const std::string_view){{}}) /* a24 */; // Default `const CharT*`
234     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
235     // CHECK-FIXES: {{^}}    (void)((const std::string_view){}) /* a24 */;
236   }
237 
238   // Static Cast
239   {
240     (void)(static_cast<std::string_view>(nullptr)) /* a25 */;
241     // CHECK-MESSAGES: :[[@LINE-1]]:42: warning: casting to basic_string_view from null is undefined; replace with the empty string
242     // CHECK-FIXES: {{^}}    (void)(static_cast<std::string_view>("")) /* a25 */;
243 
244     (void)(static_cast<std::string_view>((nullptr))) /* a26 */;
245     // CHECK-MESSAGES: :[[@LINE-1]]:42: warning: casting{{.*}}empty string
246     // CHECK-FIXES: {{^}}    (void)(static_cast<std::string_view>("")) /* a26 */;
247 
248     (void)(static_cast<const std::string_view>(nullptr)) /* a27 */;
249     // CHECK-MESSAGES: :[[@LINE-1]]:48: warning: casting{{.*}}empty string
250     // CHECK-FIXES: {{^}}    (void)(static_cast<const std::string_view>("")) /* a27 */;
251 
252     (void)(static_cast<const std::string_view>((nullptr))) /* a28 */;
253     // CHECK-MESSAGES: :[[@LINE-1]]:48: warning: casting{{.*}}empty string
254     // CHECK-FIXES: {{^}}    (void)(static_cast<const std::string_view>("")) /* a28 */;
255   }
256 }
257 
258 void stack_construction() /* b */ {
259   // Copy Initialization
260   {
261     std::string_view b1 = nullptr;
262     // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: constructing{{.*}}default
263     // CHECK-FIXES: {{^}}    std::string_view b1 = {};
264 
265     std::string_view b2 = (nullptr);
266     // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: constructing{{.*}}default
267     // CHECK-FIXES: {{^}}    std::string_view b2 = {};
268 
269     const std::string_view b3 = nullptr;
270     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
271     // CHECK-FIXES: {{^}}    const std::string_view b3 = {};
272 
273     const std::string_view b4 = (nullptr);
274     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
275     // CHECK-FIXES: {{^}}    const std::string_view b4 = {};
276   }
277 
278   // Copy Initialization With Temporary
279   {
280     std::string_view b5 = std::string_view(nullptr);
281     // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: constructing{{.*}}default
282     // CHECK-FIXES: {{^}}    std::string_view b5 = std::string_view();
283 
284     std::string_view b6 = std::string_view{nullptr};
285     // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: constructing{{.*}}default
286     // CHECK-FIXES: {{^}}    std::string_view b6 = std::string_view{};
287 
288     std::string_view b7 = (std::string_view) nullptr;
289     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
290     // CHECK-FIXES: {{^}}    std::string_view b7 = (std::string_view) {};
291 
292     std::string_view b8 = (std::string_view){nullptr};
293     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
294     // CHECK-FIXES: {{^}}    std::string_view b8 = (std::string_view){};
295 
296     std::string_view b9 = static_cast<SV>(nullptr);
297     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: casting{{.*}}empty string
298     // CHECK-FIXES: {{^}}    std::string_view b9 = static_cast<SV>("");
299   }
300 
301   // Copy List Initialization
302   {
303     std::string_view b10 = {nullptr};
304     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
305     // CHECK-FIXES: {{^}}    std::string_view b10 = {};
306 
307     std::string_view b11 = {(nullptr)};
308     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
309     // CHECK-FIXES: {{^}}    std::string_view b11 = {};
310 
311     std::string_view b12 = {{nullptr}};
312     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
313     // CHECK-FIXES: {{^}}    std::string_view b12 = {};
314 
315     std::string_view b13 = {{(nullptr)}};
316     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
317     // CHECK-FIXES: {{^}}    std::string_view b13 = {};
318 
319     std::string_view b14 = {{}}; // Default `const CharT*`
320     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
321     // CHECK-FIXES: {{^}}    std::string_view b14 = {};
322 
323     const std::string_view b15 = {nullptr};
324     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
325     // CHECK-FIXES: {{^}}    const std::string_view b15 = {};
326 
327     const std::string_view b16 = {(nullptr)};
328     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
329     // CHECK-FIXES: {{^}}    const std::string_view b16 = {};
330 
331     const std::string_view b17 = {{nullptr}};
332     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
333     // CHECK-FIXES: {{^}}    const std::string_view b17 = {};
334 
335     const std::string_view b18 = {{(nullptr)}};
336     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
337     // CHECK-FIXES: {{^}}    const std::string_view b18 = {};
338 
339     const std::string_view b19 = {{}}; // Default `const CharT*`
340     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
341     // CHECK-FIXES: {{^}}    const std::string_view b19 = {};
342   }
343 
344   // Copy List Initialization With Temporary
345   {
346     std::string_view b20 = {std::string_view(nullptr)};
347     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
348     // CHECK-FIXES: {{^}}    std::string_view b20 = {std::string_view()};
349 
350     std::string_view b21 = {std::string_view{nullptr}};
351     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
352     // CHECK-FIXES: {{^}}    std::string_view b21 = {std::string_view{}};
353 
354     std::string_view b22 = {(std::string_view) nullptr};
355     // CHECK-MESSAGES: :[[@LINE-1]]:48: warning: constructing{{.*}}default
356     // CHECK-FIXES: {{^}}    std::string_view b22 = {(std::string_view) {}};
357 
358     std::string_view b23 = {(std::string_view){nullptr}};
359     // CHECK-MESSAGES: :[[@LINE-1]]:48: warning: constructing{{.*}}default
360     // CHECK-FIXES: {{^}}    std::string_view b23 = {(std::string_view){}};
361 
362     std::string_view b24 = {static_cast<SV>(nullptr)};
363     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: casting{{.*}}empty string
364     // CHECK-FIXES: {{^}}    std::string_view b24 = {static_cast<SV>("")};
365   }
366 
367   // Direct Initialization
368   {
369     std::string_view b25(nullptr);
370     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: constructing{{.*}}default
371     // CHECK-FIXES: {{^}}    std::string_view b25;
372 
373     std::string_view b26((nullptr));
374     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: constructing{{.*}}default
375     // CHECK-FIXES: {{^}}    std::string_view b26;
376 
377     std::string_view b27({nullptr});
378     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: constructing{{.*}}default
379     // CHECK-FIXES: {{^}}    std::string_view b27;
380 
381     std::string_view b28({(nullptr)});
382     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: constructing{{.*}}default
383     // CHECK-FIXES: {{^}}    std::string_view b28;
384 
385     std::string_view b29({}); // Default `const CharT*`
386     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: constructing{{.*}}default
387     // CHECK-FIXES: {{^}}    std::string_view b29;
388 
389     const std::string_view b30(nullptr);
390     // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: constructing{{.*}}default
391     // CHECK-FIXES: {{^}}    const std::string_view b30;
392 
393     const std::string_view b31((nullptr));
394     // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: constructing{{.*}}default
395     // CHECK-FIXES: {{^}}    const std::string_view b31;
396 
397     const std::string_view b32({nullptr});
398     // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: constructing{{.*}}default
399     // CHECK-FIXES: {{^}}    const std::string_view b32;
400 
401     const std::string_view b33({(nullptr)});
402     // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: constructing{{.*}}default
403     // CHECK-FIXES: {{^}}    const std::string_view b33;
404 
405     const std::string_view b34({}); // Default `const CharT*`
406     // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: constructing{{.*}}default
407     // CHECK-FIXES: {{^}}    const std::string_view b34;
408   }
409 
410   // Direct Initialization With Temporary
411   {
412     std::string_view b35(std::string_view(nullptr));
413     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
414     // CHECK-FIXES: {{^}}    std::string_view b35(std::string_view());
415 
416     std::string_view b36(std::string_view{nullptr});
417     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
418     // CHECK-FIXES: {{^}}    std::string_view b36(std::string_view{});
419 
420     std::string_view b37((std::string_view) nullptr);
421     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: constructing{{.*}}default
422     // CHECK-FIXES: {{^}}    std::string_view b37((std::string_view) {});
423 
424     std::string_view b38((std::string_view){nullptr});
425     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: constructing{{.*}}default
426     // CHECK-FIXES: {{^}}    std::string_view b38((std::string_view){});
427 
428     std::string_view b39(static_cast<SV>(nullptr));
429     // CHECK-MESSAGES: :[[@LINE-1]]:42: warning: casting{{.*}}empty string
430     // CHECK-FIXES: {{^}}    std::string_view b39(static_cast<SV>(""));
431   }
432 
433   // Direct List Initialization
434   {
435     std::string_view b40{nullptr};
436     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
437     // CHECK-FIXES: {{^}}    std::string_view b40{};
438 
439     std::string_view b41{(nullptr)};
440     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
441     // CHECK-FIXES: {{^}}    std::string_view b41{};
442 
443     std::string_view b42{{nullptr}};
444     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
445     // CHECK-FIXES: {{^}}    std::string_view b42{};
446 
447     std::string_view b43{{(nullptr)}};
448     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
449     // CHECK-FIXES: {{^}}    std::string_view b43{};
450 
451     std::string_view b44{{}}; // Default `const CharT*`
452     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
453     // CHECK-FIXES: {{^}}    std::string_view b44{};
454 
455     const std::string_view b45{nullptr};
456     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
457     // CHECK-FIXES: {{^}}    const std::string_view b45{};
458 
459     const std::string_view b46{(nullptr)};
460     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
461     // CHECK-FIXES: {{^}}    const std::string_view b46{};
462 
463     const std::string_view b47{{nullptr}};
464     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
465     // CHECK-FIXES: {{^}}    const std::string_view b47{};
466 
467     const std::string_view b48{{(nullptr)}};
468     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
469     // CHECK-FIXES: {{^}}    const std::string_view b48{};
470 
471     const std::string_view b49{{}}; // Default `const CharT*`
472     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
473     // CHECK-FIXES: {{^}}    const std::string_view b49{};
474   }
475 
476   // Direct List Initialization With Temporary
477   {
478     std::string_view b50{std::string_view(nullptr)};
479     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
480     // CHECK-FIXES: {{^}}    std::string_view b50{std::string_view()};
481 
482     std::string_view b51{std::string_view{nullptr}};
483     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
484     // CHECK-FIXES: {{^}}    std::string_view b51{std::string_view{}};
485 
486     std::string_view b52{(std::string_view) nullptr};
487     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: constructing{{.*}}default
488     // CHECK-FIXES: {{^}}    std::string_view b52{(std::string_view) {}};
489 
490     std::string_view b53{(std::string_view){nullptr}};
491     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: constructing{{.*}}default
492     // CHECK-FIXES: {{^}}    std::string_view b53{(std::string_view){}};
493 
494     std::string_view b54{static_cast<SV>(nullptr)};
495     // CHECK-MESSAGES: :[[@LINE-1]]:42: warning: casting{{.*}}empty string
496     // CHECK-FIXES: {{^}}    std::string_view b54{static_cast<SV>("")};
497   }
498 }
499 
500 void field_construction() /* c */ {
501   // Default Member Initializaers
502 
503   struct DMICopyInitialization {
504     std::string_view c1 = nullptr;
505     // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: constructing{{.*}}default
506     // CHECK-FIXES: {{^}}    std::string_view c1 = {};
507 
508     std::string_view c2 = (nullptr);
509     // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: constructing{{.*}}default
510     // CHECK-FIXES: {{^}}    std::string_view c2 = {};
511 
512     const std::string_view c3 = nullptr;
513     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
514     // CHECK-FIXES: {{^}}    const std::string_view c3 = {};
515 
516     const std::string_view c4 = (nullptr);
517     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
518     // CHECK-FIXES: {{^}}    const std::string_view c4 = {};
519   };
520 
521   struct DMICopyInitializationWithTemporary {
522     std::string_view c5 = std::string_view(nullptr);
523     // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: constructing{{.*}}default
524     // CHECK-FIXES: {{^}}    std::string_view c5 = std::string_view();
525 
526     std::string_view c6 = std::string_view{nullptr};
527     // CHECK-MESSAGES: :[[@LINE-1]]:44: warning: constructing{{.*}}default
528     // CHECK-FIXES: {{^}}    std::string_view c6 = std::string_view{};
529 
530     std::string_view c7 = (std::string_view) nullptr;
531     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
532     // CHECK-FIXES: {{^}}    std::string_view c7 = (std::string_view) {};
533 
534     std::string_view c8 = (std::string_view){nullptr};
535     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
536     // CHECK-FIXES: {{^}}    std::string_view c8 = (std::string_view){};
537 
538     std::string_view c9 = static_cast<SV>(nullptr);
539     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: casting{{.*}}empty string
540     // CHECK-FIXES: {{^}}    std::string_view c9 = static_cast<SV>("");
541   };
542 
543   struct DMICopyListInitialization {
544     std::string_view c10 = {nullptr};
545     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
546     // CHECK-FIXES: {{^}}    std::string_view c10 = {};
547 
548     std::string_view c11 = {(nullptr)};
549     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
550     // CHECK-FIXES: {{^}}    std::string_view c11 = {};
551 
552     std::string_view c12 = {{nullptr}};
553     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
554     // CHECK-FIXES: {{^}}    std::string_view c12 = {};
555 
556     std::string_view c13 = {{(nullptr)}};
557     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
558     // CHECK-FIXES: {{^}}    std::string_view c13 = {};
559 
560     std::string_view c14 = {{}}; // Default `const CharT*`
561     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
562     // CHECK-FIXES: {{^}}    std::string_view c14 = {};
563 
564     const std::string_view c15 = {nullptr};
565     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
566     // CHECK-FIXES: {{^}}    const std::string_view c15 = {};
567 
568     const std::string_view c16 = {(nullptr)};
569     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
570     // CHECK-FIXES: {{^}}    const std::string_view c16 = {};
571 
572     const std::string_view c17 = {{nullptr}};
573     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
574     // CHECK-FIXES: {{^}}    const std::string_view c17 = {};
575 
576     const std::string_view c18 = {{(nullptr)}};
577     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
578     // CHECK-FIXES: {{^}}    const std::string_view c18 = {};
579 
580     const std::string_view c19 = {{}}; // Default `const CharT*`
581     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
582     // CHECK-FIXES: {{^}}    const std::string_view c19 = {};
583   };
584 
585   struct DMICopyListInitializationWithTemporary {
586     std::string_view c20 = {std::string_view(nullptr)};
587     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
588     // CHECK-FIXES: {{^}}    std::string_view c20 = {std::string_view()};
589 
590     std::string_view c21 = {std::string_view{nullptr}};
591     // CHECK-MESSAGES: :[[@LINE-1]]:46: warning: constructing{{.*}}default
592     // CHECK-FIXES: {{^}}    std::string_view c21 = {std::string_view{}};
593 
594     std::string_view c22 = {(std::string_view) nullptr};
595     // CHECK-MESSAGES: :[[@LINE-1]]:48: warning: constructing{{.*}}default
596     // CHECK-FIXES: {{^}}    std::string_view c22 = {(std::string_view) {}};
597 
598     std::string_view c23 = {(std::string_view){nullptr}};
599     // CHECK-MESSAGES: :[[@LINE-1]]:48: warning: constructing{{.*}}default
600     // CHECK-FIXES: {{^}}    std::string_view c23 = {(std::string_view){}};
601 
602     std::string_view c24 = {static_cast<SV>(nullptr)};
603     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: casting{{.*}}empty string
604     // CHECK-FIXES: {{^}}    std::string_view c24 = {static_cast<SV>("")};
605   };
606 
607   struct DMIDirectListInitialization {
608     std::string_view c25{nullptr};
609     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
610     // CHECK-FIXES: {{^}}    std::string_view c25{};
611 
612     std::string_view c26{(nullptr)};
613     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
614     // CHECK-FIXES: {{^}}    std::string_view c26{};
615 
616     std::string_view c27{{nullptr}};
617     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
618     // CHECK-FIXES: {{^}}    std::string_view c27{};
619 
620     std::string_view c28{{(nullptr)}};
621     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
622     // CHECK-FIXES: {{^}}    std::string_view c28{};
623 
624     std::string_view c29{{}}; // Default `const CharT*`
625     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: constructing{{.*}}default
626     // CHECK-FIXES: {{^}}    std::string_view c29{};
627 
628     const std::string_view c30{nullptr};
629     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
630     // CHECK-FIXES: {{^}}    const std::string_view c30{};
631 
632     const std::string_view c31{(nullptr)};
633     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
634     // CHECK-FIXES: {{^}}    const std::string_view c31{};
635 
636     const std::string_view c32{{nullptr}};
637     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
638     // CHECK-FIXES: {{^}}    const std::string_view c32{};
639 
640     const std::string_view c33{{(nullptr)}};
641     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
642     // CHECK-FIXES: {{^}}    const std::string_view c33{};
643 
644     const std::string_view c34{{}}; // Default `const CharT*`
645     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
646     // CHECK-FIXES: {{^}}    const std::string_view c34{};
647   };
648 
649   struct DMIDirectListInitializationWithTemporary {
650     std::string_view c35{std::string_view(nullptr)};
651     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
652     // CHECK-FIXES: {{^}}    std::string_view c35{std::string_view()};
653 
654     std::string_view c36{std::string_view{nullptr}};
655     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
656     // CHECK-FIXES: {{^}}    std::string_view c36{std::string_view{}};
657 
658     std::string_view c37{(std::string_view) nullptr};
659     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: constructing{{.*}}default
660     // CHECK-FIXES: {{^}}    std::string_view c37{(std::string_view) {}};
661 
662     std::string_view c38{(std::string_view){nullptr}};
663     // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: constructing{{.*}}default
664     // CHECK-FIXES: {{^}}    std::string_view c38{(std::string_view){}};
665 
666     std::string_view c39{static_cast<SV>(nullptr)};
667     // CHECK-MESSAGES: :[[@LINE-1]]:42: warning: casting{{.*}}empty string
668     // CHECK-FIXES: {{^}}    std::string_view c39{static_cast<SV>("")};
669   };
670 
671   // Constructor Initializers
672 
673   class CIDirectInitialization {
674     std::string_view c40;
675     std::string_view c41;
676     std::string_view c42;
677     std::string_view c43;
678     std::string_view c44;
679 
680     CIDirectInitialization()
681         : c40(nullptr),
682           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
683           // CHECK-FIXES: {{^}}        : c40(),
684 
685           c41((nullptr)),
686           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
687           // CHECK-FIXES: {{^}}          c41(),
688 
689           c42({nullptr}),
690           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
691           // CHECK-FIXES: {{^}}          c42(),
692 
693           c43({(nullptr)}),
694           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
695           // CHECK-FIXES: {{^}}          c43(),
696 
697           c44({}) { // Default `const CharT*`
698       // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
699       // CHECK-FIXES: {{^}}          c44() {
700     }
701   };
702 
703   class CIDirectInitializationWithTemporary {
704     std::string_view c45;
705     std::string_view c46;
706     std::string_view c47;
707     std::string_view c48;
708     std::string_view c49;
709 
710     CIDirectInitializationWithTemporary()
711         : c45(std::string_view(nullptr)),
712           // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
713           // CHECK-FIXES: {{^}}        : c45(std::string_view()),
714 
715           c46(std::string_view{nullptr}),
716           // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
717           // CHECK-FIXES: {{^}}          c46(std::string_view{}),
718 
719           c47((std::string_view) nullptr),
720           // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
721           // CHECK-FIXES: {{^}}          c47((std::string_view) {}),
722 
723           c48((std::string_view){nullptr}),
724           // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
725           // CHECK-FIXES: {{^}}          c48((std::string_view){}),
726 
727           c49(static_cast<SV>(nullptr)) {
728       // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: casting{{.*}}empty string
729       // CHECK-FIXES: {{^}}          c49(static_cast<SV>("")) {
730     }
731   };
732 
733   class CIDirectListInitialization {
734     std::string_view c50;
735     std::string_view c51;
736     std::string_view c52;
737     std::string_view c53;
738     std::string_view c54;
739 
740     CIDirectListInitialization()
741         : c50{nullptr},
742           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
743           // CHECK-FIXES: {{^}}        : c50{},
744 
745           c51{(nullptr)},
746           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
747           // CHECK-FIXES: {{^}}          c51{},
748 
749           c52{{nullptr}},
750           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
751           // CHECK-FIXES: {{^}}          c52{},
752 
753           c53{{(nullptr)}},
754           // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
755           // CHECK-FIXES: {{^}}          c53{},
756 
757           c54{{}} { // Default `const CharT*`
758       // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: constructing{{.*}}default
759       // CHECK-FIXES: {{^}}          c54{} {
760     }
761   };
762 
763   class CIDirectListInitializationWithTemporary {
764     std::string_view c55;
765     std::string_view c56;
766     std::string_view c57;
767     std::string_view c58;
768     std::string_view c59;
769 
770     CIDirectListInitializationWithTemporary()
771         : c55{std::string_view(nullptr)},
772           // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
773           // CHECK-FIXES: {{^}}        : c55{std::string_view()},
774 
775           c56{std::string_view{nullptr}},
776           // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
777           // CHECK-FIXES: {{^}}          c56{std::string_view{}},
778 
779           c57{(std::string_view) nullptr},
780           // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
781           // CHECK-FIXES: {{^}}          c57{(std::string_view) {}},
782 
783           c58{(std::string_view){nullptr}},
784           // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
785           // CHECK-FIXES: {{^}}          c58{(std::string_view){}},
786 
787           c59{static_cast<SV>(nullptr)} {
788       // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: casting{{.*}}empty string
789       // CHECK-FIXES: {{^}}          c59{static_cast<SV>("")} {
790     }
791   };
792 }
793 
794 void default_argument_construction() /* d */ {
795   // Copy Initialization
796   {
797     void d1(std::string_view sv = nullptr);
798     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
799     // CHECK-FIXES: {{^}}    void d1(std::string_view sv = {});
800 
801     void d2(std::string_view sv = (nullptr));
802     // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
803     // CHECK-FIXES: {{^}}    void d2(std::string_view sv = {});
804 
805     void d3(const std::string_view sv = nullptr);
806     // CHECK-MESSAGES: :[[@LINE-1]]:41: warning: constructing{{.*}}default
807     // CHECK-FIXES: {{^}}    void d3(const std::string_view sv = {});
808 
809     void d4(const std::string_view sv = (nullptr));
810     // CHECK-MESSAGES: :[[@LINE-1]]:41: warning: constructing{{.*}}default
811     // CHECK-FIXES: {{^}}    void d4(const std::string_view sv = {});
812   }
813 
814   // Copy Initialization With Temporary
815   {
816     void d5(std::string_view sv = std::string_view(nullptr));
817     // CHECK-MESSAGES: :[[@LINE-1]]:52: warning: constructing{{.*}}default
818     // CHECK-FIXES: {{^}}    void d5(std::string_view sv = std::string_view());
819 
820     void d6(std::string_view sv = std::string_view{nullptr});
821     // CHECK-MESSAGES: :[[@LINE-1]]:52: warning: constructing{{.*}}default
822     // CHECK-FIXES: {{^}}    void d6(std::string_view sv = std::string_view{});
823 
824     void d7(std::string_view sv = (std::string_view) nullptr);
825     // CHECK-MESSAGES: :[[@LINE-1]]:54: warning: constructing{{.*}}default
826     // CHECK-FIXES: {{^}}    void d7(std::string_view sv = (std::string_view) {});
827 
828     void d8(std::string_view sv = (std::string_view){nullptr});
829     // CHECK-MESSAGES: :[[@LINE-1]]:54: warning: constructing{{.*}}default
830     // CHECK-FIXES: {{^}}    void d8(std::string_view sv = (std::string_view){});
831 
832     void d9(std::string_view sv = static_cast<SV>(nullptr));
833     // CHECK-MESSAGES: :[[@LINE-1]]:51: warning: casting{{.*}}empty string
834     // CHECK-FIXES: {{^}}    void d9(std::string_view sv = static_cast<SV>(""));
835   }
836 
837   // Copy List Initialization
838   {
839     void d10(std::string_view sv = {nullptr});
840     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
841     // CHECK-FIXES: {{^}}    void d10(std::string_view sv = {});
842 
843     void d11(std::string_view sv = {(nullptr)});
844     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
845     // CHECK-FIXES: {{^}}    void d11(std::string_view sv = {});
846 
847     void d12(std::string_view sv = {{nullptr}});
848     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
849     // CHECK-FIXES: {{^}}    void d12(std::string_view sv = {});
850 
851     void d13(std::string_view sv = {{(nullptr)}});
852     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
853     // CHECK-FIXES: {{^}}    void d13(std::string_view sv = {});
854 
855     void d14(std::string_view sv = {{}}); // Default `const CharT*`
856     // CHECK-MESSAGES: :[[@LINE-1]]:37: warning: constructing{{.*}}default
857     // CHECK-FIXES: {{^}}    void d14(std::string_view sv = {});
858 
859     void d15(const std::string_view sv = {nullptr});
860     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
861     // CHECK-FIXES: {{^}}    void d15(const std::string_view sv = {});
862 
863     void d16(const std::string_view sv = {(nullptr)});
864     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
865     // CHECK-FIXES: {{^}}    void d16(const std::string_view sv = {});
866 
867     void d17(const std::string_view sv = {{nullptr}});
868     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
869     // CHECK-FIXES: {{^}}    void d17(const std::string_view sv = {});
870 
871     void d18(const std::string_view sv = {{(nullptr)}});
872     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
873     // CHECK-FIXES: {{^}}    void d18(const std::string_view sv = {});
874 
875     void d19(const std::string_view sv = {{}}); // Default `const CharT*`
876     // CHECK-MESSAGES: :[[@LINE-1]]:43: warning: constructing{{.*}}default
877     // CHECK-FIXES: {{^}}    void d19(const std::string_view sv = {});
878   }
879 
880   // Copy List Initialization With Temporary
881   {
882     void d20(std::string_view sv = {std::string_view(nullptr)});
883     // CHECK-MESSAGES: :[[@LINE-1]]:54: warning: constructing{{.*}}default
884     // CHECK-FIXES: {{^}}    void d20(std::string_view sv = {std::string_view()});
885 
886     void d21(std::string_view sv = {std::string_view{nullptr}});
887     // CHECK-MESSAGES: :[[@LINE-1]]:54: warning: constructing{{.*}}default
888     // CHECK-FIXES: {{^}}    void d21(std::string_view sv = {std::string_view{}});
889 
890     void d22(std::string_view sv = {(std::string_view) nullptr});
891     // CHECK-MESSAGES: :[[@LINE-1]]:56: warning: constructing{{.*}}default
892     // CHECK-FIXES: {{^}}    void d22(std::string_view sv = {(std::string_view) {}});
893 
894     void d23(std::string_view sv = {(std::string_view){nullptr}});
895     // CHECK-MESSAGES: :[[@LINE-1]]:56: warning: constructing{{.*}}default
896     // CHECK-FIXES: {{^}}    void d23(std::string_view sv = {(std::string_view){}});
897 
898     void d24(std::string_view sv = {static_cast<SV>(nullptr)});
899     // CHECK-MESSAGES: :[[@LINE-1]]:53: warning: casting{{.*}}empty string
900     // CHECK-FIXES: {{^}}    void d24(std::string_view sv = {static_cast<SV>("")});
901   }
902 }
903 
904 void heap_construction() /* e */ {
905   // Direct Initialization
906   {
907     (void)(new std::string_view(nullptr)) /* e1 */;
908     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
909     // CHECK-FIXES: {{^}}    (void)(new std::string_view()) /* e1 */;
910 
911     (void)(new std::string_view((nullptr))) /* e2 */;
912     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
913     // CHECK-FIXES: {{^}}    (void)(new std::string_view()) /* e2 */;
914 
915     (void)(new std::string_view({nullptr})) /* e3 */;
916     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
917     // CHECK-FIXES: {{^}}    (void)(new std::string_view()) /* e3 */;
918 
919     (void)(new std::string_view({(nullptr)})) /* e4 */;
920     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
921     // CHECK-FIXES: {{^}}    (void)(new std::string_view()) /* e4 */;
922 
923     (void)(new std::string_view({})) /* e5 */; // Default `const CharT*`
924     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
925     // CHECK-FIXES: {{^}}    (void)(new std::string_view()) /* e5 */;
926 
927     (void)(new const std::string_view(nullptr)) /* e6 */;
928     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
929     // CHECK-FIXES: {{^}}    (void)(new const std::string_view()) /* e6 */;
930 
931     (void)(new const std::string_view((nullptr))) /* e7 */;
932     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
933     // CHECK-FIXES: {{^}}    (void)(new const std::string_view()) /* e7 */;
934 
935     (void)(new const std::string_view({nullptr})) /* e8 */;
936     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
937     // CHECK-FIXES: {{^}}    (void)(new const std::string_view()) /* e8 */;
938 
939     (void)(new const std::string_view({(nullptr)})) /* e9 */;
940     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
941     // CHECK-FIXES: {{^}}    (void)(new const std::string_view()) /* e9 */;
942 
943     (void)(new const std::string_view({})) /* e10 */; // Default `const CharT*`
944     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
945     // CHECK-FIXES: {{^}}    (void)(new const std::string_view()) /* e10 */;
946   }
947 
948   // Direct Initialization With Temporary
949   {
950     (void)(new std::string_view(std::string_view(nullptr))) /* e11 */;
951     // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: constructing{{.*}}default
952     // CHECK-FIXES: {{^}}    (void)(new std::string_view(std::string_view())) /* e11 */;
953 
954     (void)(new std::string_view(std::string_view{nullptr})) /* e12 */;
955     // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: constructing{{.*}}default
956     // CHECK-FIXES: {{^}}    (void)(new std::string_view(std::string_view{})) /* e12 */;
957 
958     (void)(new std::string_view((std::string_view) nullptr)) /* e13 */;
959     // CHECK-MESSAGES: :[[@LINE-1]]:52: warning: constructing{{.*}}default
960     // CHECK-FIXES: {{^}}    (void)(new std::string_view((std::string_view) {})) /* e13 */;
961 
962     (void)(new std::string_view((std::string_view){nullptr})) /* e14 */;
963     // CHECK-MESSAGES: :[[@LINE-1]]:52: warning: constructing{{.*}}default
964     // CHECK-FIXES: {{^}}    (void)(new std::string_view((std::string_view){})) /* e14 */;
965 
966     (void)(new std::string_view(static_cast<SV>(nullptr))) /* e15 */;
967     // CHECK-MESSAGES: :[[@LINE-1]]:49: warning: casting{{.*}}empty string
968     // CHECK-FIXES: {{^}}    (void)(new std::string_view(static_cast<SV>(""))) /* e15 */;
969   }
970 
971   // Direct List Initialization
972   {
973     (void)(new std::string_view{nullptr}) /* e16 */;
974     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
975     // CHECK-FIXES: {{^}}    (void)(new std::string_view{}) /* e16 */;
976 
977     (void)(new std::string_view{(nullptr)}) /* e17 */;
978     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
979     // CHECK-FIXES: {{^}}    (void)(new std::string_view{}) /* e17 */;
980 
981     (void)(new std::string_view{{nullptr}}) /* e18 */;
982     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
983     // CHECK-FIXES: {{^}}    (void)(new std::string_view{}) /* e18 */;
984 
985     (void)(new std::string_view{{(nullptr)}}) /* e19 */;
986     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
987     // CHECK-FIXES: {{^}}    (void)(new std::string_view{}) /* e19 */;
988 
989     (void)(new std::string_view{{}}) /* e20 */; // Default `const CharT*`
990     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
991     // CHECK-FIXES: {{^}}    (void)(new std::string_view{}) /* e20 */;
992 
993     (void)(new const std::string_view{nullptr}) /* e21 */;
994     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
995     // CHECK-FIXES: {{^}}    (void)(new const std::string_view{}) /* e21 */;
996 
997     (void)(new const std::string_view{(nullptr)}) /* e22 */;
998     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
999     // CHECK-FIXES: {{^}}    (void)(new const std::string_view{}) /* e22 */;
1000 
1001     (void)(new const std::string_view{{nullptr}}) /* e23 */;
1002     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
1003     // CHECK-FIXES: {{^}}    (void)(new const std::string_view{}) /* e23 */;
1004 
1005     (void)(new const std::string_view{{(nullptr)}}) /* e24 */;
1006     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
1007     // CHECK-FIXES: {{^}}    (void)(new const std::string_view{}) /* e24 */;
1008 
1009     (void)(new const std::string_view{{}}) /* e25 */; // Default `const CharT*`
1010     // CHECK-MESSAGES: :[[@LINE-1]]:39: warning: constructing{{.*}}default
1011     // CHECK-FIXES: {{^}}    (void)(new const std::string_view{}) /* e25 */;
1012   }
1013 
1014   // Direct List Initialization With Temporary
1015   {
1016     (void)(new std::string_view{std::string_view(nullptr)}) /* e26 */;
1017     // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: constructing{{.*}}default
1018     // CHECK-FIXES: {{^}}    (void)(new std::string_view{std::string_view()}) /* e26 */;
1019 
1020     (void)(new std::string_view{std::string_view{nullptr}}) /* e27 */;
1021     // CHECK-MESSAGES: :[[@LINE-1]]:50: warning: constructing{{.*}}default
1022     // CHECK-FIXES: {{^}}    (void)(new std::string_view{std::string_view{}}) /* e27 */;
1023 
1024     (void)(new std::string_view{(std::string_view) nullptr}) /* e28 */;
1025     // CHECK-MESSAGES: :[[@LINE-1]]:52: warning: constructing{{.*}}default
1026     // CHECK-FIXES: {{^}}    (void)(new std::string_view{(std::string_view) {}}) /* e28 */;
1027 
1028     (void)(new std::string_view{(std::string_view){nullptr}}) /* e29 */;
1029     // CHECK-MESSAGES: :[[@LINE-1]]:52: warning: constructing{{.*}}default
1030     // CHECK-FIXES: {{^}}    (void)(new std::string_view{(std::string_view){}}) /* e29 */;
1031 
1032     (void)(new std::string_view{static_cast<SV>(nullptr)}) /* e30 */;
1033     // CHECK-MESSAGES: :[[@LINE-1]]:49: warning: casting{{.*}}empty string
1034     // CHECK-FIXES: {{^}}    (void)(new std::string_view{static_cast<SV>("")}) /* e30 */;
1035   }
1036 }
1037 
1038 void function_argument_initialization() /* f */ {
1039   // Function Argument Initialization
1040   {
1041     function(nullptr) /* f1 */;
1042     // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: passing null as basic_string_view is undefined; replace with the empty string
1043     // CHECK-FIXES: {{^}}    function("") /* f1 */;
1044 
1045     function((nullptr)) /* f2 */;
1046     // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: passing{{.*}}empty string
1047     // CHECK-FIXES: {{^}}    function("") /* f2 */;
1048 
1049     function({nullptr}) /* f3 */;
1050     // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: passing{{.*}}empty string
1051     // CHECK-FIXES: {{^}}    function("") /* f3 */;
1052 
1053     function({(nullptr)}) /* f4 */;
1054     // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: passing{{.*}}empty string
1055     // CHECK-FIXES: {{^}}    function("") /* f4 */;
1056 
1057     function({{}}) /* f5 */; // Default `const CharT*`
1058     // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: passing{{.*}}empty string
1059     // CHECK-FIXES: {{^}}    function("") /* f5 */;
1060   }
1061 
1062   // Function Argument Initialization With Temporary
1063   {
1064     function(std::string_view(nullptr)) /* f6 */;
1065     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
1066     // CHECK-FIXES: {{^}}    function(std::string_view()) /* f6 */;
1067 
1068     function(std::string_view{nullptr}) /* f7 */;
1069     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: constructing{{.*}}default
1070     // CHECK-FIXES: {{^}}    function(std::string_view{}) /* f7 */;
1071 
1072     function((std::string_view) nullptr) /* f8 */;
1073     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
1074     // CHECK-FIXES: {{^}}    function((std::string_view) {}) /* f8 */;
1075 
1076     function((std::string_view){nullptr}) /* f9 */;
1077     // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
1078     // CHECK-FIXES: {{^}}    function((std::string_view){}) /* f9 */;
1079 
1080     function(static_cast<SV>(nullptr)) /* f10 */;
1081     // CHECK-MESSAGES: :[[@LINE-1]]:30: warning: casting{{.*}}empty string
1082     // CHECK-FIXES: {{^}}    function(static_cast<SV>("")) /* f10 */;
1083   }
1084 }
1085 
1086 void assignment(std::string_view sv) /* g */ {
1087   // Assignment
1088   {
1089     sv = nullptr /* g1 */;
1090     // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: assignment to basic_string_view from null is undefined; replace with the default constructor
1091     // CHECK-FIXES: {{^}}    sv = {} /* g1 */;
1092 
1093     sv = (nullptr) /* g2 */;
1094     // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: assignment{{.*}}default
1095     // CHECK-FIXES: {{^}}    sv = {} /* g2 */;
1096 
1097     sv = {nullptr} /* g3 */;
1098     // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: assignment{{.*}}default
1099     // CHECK-FIXES: {{^}}    sv = {} /* g3 */;
1100 
1101     sv = {(nullptr)} /* g4 */;
1102     // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: assignment{{.*}}default
1103     // CHECK-FIXES: {{^}}    sv = {} /* g4 */;
1104 
1105     sv = {{}} /* g5 */; // Default `const CharT*`
1106     // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: assignment{{.*}}default
1107     // CHECK-FIXES: {{^}}    sv = {} /* g5 */;
1108   }
1109 
1110   // Assignment With Temporary
1111   {
1112     sv = std::string_view(nullptr) /* g6 */;
1113     // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: constructing{{.*}}default
1114     // CHECK-FIXES: {{^}}    sv = std::string_view() /* g6 */;
1115 
1116     sv = std::string_view{nullptr} /* g7 */;
1117     // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: constructing{{.*}}default
1118     // CHECK-FIXES: {{^}}    sv = std::string_view{} /* g7 */;
1119 
1120     sv = (std::string_view) nullptr /* g8 */;
1121     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
1122     // CHECK-FIXES: {{^}}    sv = (std::string_view) {} /* g8 */;
1123 
1124     sv = (std::string_view){nullptr} /* g9 */;
1125     // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: constructing{{.*}}default
1126     // CHECK-FIXES: {{^}}    sv = (std::string_view){} /* g9 */;
1127 
1128     sv = static_cast<SV>(nullptr) /* g10 */;
1129     // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: casting{{.*}}empty string
1130     // CHECK-FIXES: {{^}}    sv = static_cast<SV>("") /* g10 */;
1131   }
1132 }
1133 
1134 void pointer_assignment(std::string_view *sv_ptr) /* h */ {
1135   // Assignment
1136   {
1137     *sv_ptr = nullptr /* h1 */;
1138     // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: assignment{{.*}}default
1139     // CHECK-FIXES: {{^}}    *sv_ptr = {} /* h1 */;
1140 
1141     *sv_ptr = (nullptr) /* h2 */;
1142     // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: assignment{{.*}}default
1143     // CHECK-FIXES: {{^}}    *sv_ptr = {} /* h2 */;
1144 
1145     *sv_ptr = {nullptr} /* h3 */;
1146     // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: assignment{{.*}}default
1147     // CHECK-FIXES: {{^}}    *sv_ptr = {} /* h3 */;
1148 
1149     *sv_ptr = {(nullptr)} /* h4 */;
1150     // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: assignment{{.*}}default
1151     // CHECK-FIXES: {{^}}    *sv_ptr = {} /* h4 */;
1152 
1153     *sv_ptr = {{}} /* h5 */; // Default `const CharT*`
1154     // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: assignment{{.*}}default
1155     // CHECK-FIXES: {{^}}    *sv_ptr = {} /* h5 */;
1156   }
1157 
1158   // Assignment With Temporary
1159   {
1160     *sv_ptr = std::string_view(nullptr) /* h6 */;
1161     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
1162     // CHECK-FIXES: {{^}}    *sv_ptr = std::string_view() /* h6 */;
1163 
1164     *sv_ptr = std::string_view{nullptr} /* h7 */;
1165     // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
1166     // CHECK-FIXES: {{^}}    *sv_ptr = std::string_view{} /* h7 */;
1167 
1168     *sv_ptr = (std::string_view) nullptr /* h8 */;
1169     // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
1170     // CHECK-FIXES: {{^}}    *sv_ptr = (std::string_view) {} /* h8 */;
1171 
1172     *sv_ptr = (std::string_view){nullptr} /* h9 */;
1173     // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
1174     // CHECK-FIXES: {{^}}    *sv_ptr = (std::string_view){} /* h9 */;
1175 
1176     *sv_ptr = static_cast<SV>(nullptr) /* h10 */;
1177     // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: casting{{.*}}empty string
1178     // CHECK-FIXES: {{^}}    *sv_ptr = static_cast<SV>("") /* h10 */;
1179   }
1180 }
1181 
1182 void lesser_comparison(std::string_view sv) /* i */ {
1183   // Without Equality
1184   {
1185     (void)(sv < nullptr) /* i1 */;
1186     // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: comparing basic_string_view to null is undefined; replace with the empty string
1187     // CHECK-FIXES: {{^}}    (void)(sv < "") /* i1 */;
1188 
1189     (void)(sv < (nullptr)) /* i2 */;
1190     // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: comparing{{.*}}empty string
1191     // CHECK-FIXES: {{^}}    (void)(sv < "") /* i2 */;
1192 
1193     (void)(nullptr < sv) /* i3 */;
1194     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1195     // CHECK-FIXES: {{^}}    (void)("" < sv) /* i3 */;
1196 
1197     (void)((nullptr) < sv) /* i4 */;
1198     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1199     // CHECK-FIXES: {{^}}    (void)("" < sv) /* i4 */;
1200   }
1201 
1202   // With Equality
1203   {
1204     (void)(sv <= nullptr) /* i5 */;
1205     // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: comparing{{.*}}empty string
1206     // CHECK-FIXES: {{^}}    (void)(sv <= "") /* i5 */;
1207 
1208     (void)(sv <= (nullptr)) /* i6 */;
1209     // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: comparing{{.*}}empty string
1210     // CHECK-FIXES: {{^}}    (void)(sv <= "") /* i6 */;
1211 
1212     (void)(nullptr <= sv) /* i7 */;
1213     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1214     // CHECK-FIXES: {{^}}    (void)("" <= sv) /* i7 */;
1215 
1216     (void)((nullptr) <= sv) /* i8 */;
1217     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1218     // CHECK-FIXES: {{^}}    (void)("" <= sv) /* i8 */;
1219   }
1220 }
1221 
1222 void pointer_lesser_comparison(std::string_view *sv_ptr) /* j */ {
1223   // Without Equality
1224   {
1225     (void)(*sv_ptr < nullptr) /* j1 */;
1226     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: comparing{{.*}}empty string
1227     // CHECK-FIXES: {{^}}    (void)(*sv_ptr < "") /* j1 */;
1228 
1229     (void)(*sv_ptr < (nullptr)) /* j2 */;
1230     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: comparing{{.*}}empty string
1231     // CHECK-FIXES: {{^}}    (void)(*sv_ptr < "") /* j2 */;
1232 
1233     (void)(nullptr < *sv_ptr) /* j3 */;
1234     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1235     // CHECK-FIXES: {{^}}    (void)("" < *sv_ptr) /* j3 */;
1236 
1237     (void)((nullptr) < *sv_ptr) /* j4 */;
1238     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1239     // CHECK-FIXES: {{^}}    (void)("" < *sv_ptr) /* j4 */;
1240   }
1241 
1242   // With Equality
1243   {
1244     (void)(*sv_ptr <= nullptr) /* j5 */;
1245     // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: comparing{{.*}}empty string
1246     // CHECK-FIXES: {{^}}    (void)(*sv_ptr <= "") /* j5 */;
1247 
1248     (void)(*sv_ptr <= (nullptr)) /* j6 */;
1249     // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: comparing{{.*}}empty string
1250     // CHECK-FIXES: {{^}}    (void)(*sv_ptr <= "") /* j6 */;
1251 
1252     (void)(nullptr <= *sv_ptr) /* j7 */;
1253     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1254     // CHECK-FIXES: {{^}}    (void)("" <= *sv_ptr) /* j7 */;
1255 
1256     (void)((nullptr) <= *sv_ptr) /* j8 */;
1257     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1258     // CHECK-FIXES: {{^}}    (void)("" <= *sv_ptr) /* j8 */;
1259   }
1260 }
1261 
1262 void greater_comparison(std::string_view sv) /* k */ {
1263   // Without Equality
1264   {
1265     (void)(sv > nullptr) /* k1 */;
1266     // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: comparing{{.*}}empty string
1267     // CHECK-FIXES: {{^}}    (void)(sv > "") /* k1 */;
1268 
1269     (void)(sv > (nullptr)) /* k2 */;
1270     // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: comparing{{.*}}empty string
1271     // CHECK-FIXES: {{^}}    (void)(sv > "") /* k2 */;
1272 
1273     (void)(nullptr > sv) /* k3 */;
1274     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1275     // CHECK-FIXES: {{^}}    (void)("" > sv) /* k3 */;
1276 
1277     (void)((nullptr) > sv) /* k4 */;
1278     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1279     // CHECK-FIXES: {{^}}    (void)("" > sv) /* k4 */;
1280   }
1281 
1282   // With Equality
1283   {
1284     (void)(sv >= nullptr) /* k5 */;
1285     // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: comparing{{.*}}empty string
1286     // CHECK-FIXES: {{^}}    (void)(sv >= "") /* k5 */;
1287 
1288     (void)(sv >= (nullptr)) /* k6 */;
1289     // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: comparing{{.*}}empty string
1290     // CHECK-FIXES: {{^}}    (void)(sv >= "") /* k6 */;
1291 
1292     (void)(nullptr >= sv) /* k7 */;
1293     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1294     // CHECK-FIXES: {{^}}    (void)("" >= sv) /* k7 */;
1295 
1296     (void)((nullptr) >= sv) /* k8 */;
1297     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1298     // CHECK-FIXES: {{^}}    (void)("" >= sv) /* k8 */;
1299   }
1300 }
1301 
1302 void pointer_greater_comparison(std::string_view *sv_ptr) /* l */ {
1303   // Without Equality
1304   {
1305     (void)(*sv_ptr > nullptr) /* l1 */;
1306     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: comparing{{.*}}empty string
1307     // CHECK-FIXES: {{^}}    (void)(*sv_ptr > "") /* l1 */;
1308 
1309     (void)(*sv_ptr > (nullptr)) /* l2 */;
1310     // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: comparing{{.*}}empty string
1311     // CHECK-FIXES: {{^}}    (void)(*sv_ptr > "") /* l2 */;
1312 
1313     (void)(nullptr > *sv_ptr) /* l3 */;
1314     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1315     // CHECK-FIXES: {{^}}    (void)("" > *sv_ptr) /* l3 */;
1316 
1317     (void)((nullptr) > *sv_ptr) /* l4 */;
1318     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1319     // CHECK-FIXES: {{^}}    (void)("" > *sv_ptr) /* l4 */;
1320   }
1321 
1322   // With Equality
1323   {
1324     (void)(*sv_ptr >= nullptr) /* l5 */;
1325     // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: comparing{{.*}}empty string
1326     // CHECK-FIXES: {{^}}    (void)(*sv_ptr >= "") /* l5 */;
1327 
1328     (void)(*sv_ptr >= (nullptr)) /* l6 */;
1329     // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: comparing{{.*}}empty string
1330     // CHECK-FIXES: {{^}}    (void)(*sv_ptr >= "") /* l6 */;
1331 
1332     (void)(nullptr >= *sv_ptr) /* l7 */;
1333     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1334     // CHECK-FIXES: {{^}}    (void)("" >= *sv_ptr) /* l7 */;
1335 
1336     (void)((nullptr) >= *sv_ptr) /* l8 */;
1337     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}empty string
1338     // CHECK-FIXES: {{^}}    (void)("" >= *sv_ptr) /* l8 */;
1339   }
1340 }
1341 
1342 void relative_comparison_with_temporary(std::string_view sv) /* m */ {
1343   (void)(sv < std::string_view(nullptr)) /* m1 */;
1344   // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
1345   // CHECK-FIXES: {{^}}  (void)(sv < std::string_view()) /* m1 */;
1346 
1347   (void)(sv < std::string_view{nullptr}) /* m2 */;
1348   // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: constructing{{.*}}default
1349   // CHECK-FIXES: {{^}}  (void)(sv < std::string_view{}) /* m2 */;
1350 
1351   (void)(sv < (std::string_view) nullptr) /* m3 */;
1352   // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
1353   // CHECK-FIXES: {{^}}  (void)(sv < (std::string_view) {}) /* m3 */;
1354 
1355   (void)(sv < (std::string_view){nullptr}) /* m4 */;
1356   // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: constructing{{.*}}default
1357   // CHECK-FIXES: {{^}}  (void)(sv < (std::string_view){}) /* m4 */;
1358 
1359   (void)(sv < static_cast<SV>(nullptr)) /* m5 */;
1360   // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: casting{{.*}}empty string
1361   // CHECK-FIXES: {{^}}  (void)(sv < static_cast<SV>("")) /* m5 */;
1362 }
1363 
1364 void equality_comparison(std::string_view sv) /* n */ {
1365   // Empty Without Parens
1366   {
1367     (void)(sv == nullptr) /* n1 */;
1368     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing basic_string_view to null is undefined; replace with the emptiness query
1369     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n1 */;
1370 
1371     (void)(sv == (nullptr)) /* n2 */;
1372     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1373     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n2 */;
1374 
1375     (void)(nullptr == sv) /* n3 */;
1376     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1377     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n3 */;
1378 
1379     (void)((nullptr) == sv) /* n4 */;
1380     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1381     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n4 */;
1382   }
1383 
1384   // Empty With Parens
1385   {
1386     (void)((sv) == nullptr) /* n5 */;
1387     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing basic_string_view to null is undefined; replace with the emptiness query
1388     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n5 */;
1389 
1390     (void)((sv) == (nullptr)) /* n6 */;
1391     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1392     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n6 */;
1393 
1394     (void)(nullptr == (sv)) /* n7 */;
1395     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1396     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n7 */;
1397 
1398     (void)((nullptr) == (sv)) /* n8 */;
1399     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1400     // CHECK-FIXES: {{^}}    (void)(sv.empty()) /* n8 */;
1401   }
1402 
1403   // Non-Empty Without Parens
1404   {
1405     (void)((sv) != nullptr) /* n9 */;
1406     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1407     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n9 */;
1408 
1409     (void)((sv) != (nullptr)) /* n10 */;
1410     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1411     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n10 */;
1412 
1413     (void)(nullptr != (sv)) /* n11 */;
1414     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1415     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n11 */;
1416 
1417     (void)((nullptr) != (sv)) /* n12 */;
1418     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1419     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n12 */;
1420   }
1421 
1422   // Non-Empty With Parens
1423   {
1424     (void)((sv) != nullptr) /* n13 */;
1425     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1426     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n13 */;
1427 
1428     (void)((sv) != (nullptr)) /* n14 */;
1429     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1430     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n14 */;
1431 
1432     (void)(nullptr != (sv)) /* n15 */;
1433     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1434     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n15 */;
1435 
1436     (void)((nullptr) != (sv)) /* n16 */;
1437     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1438     // CHECK-FIXES: {{^}}    (void)(!sv.empty()) /* n16 */;
1439   }
1440 }
1441 
1442 void pointer_equality_comparison(std::string_view *sv_ptr) /* o */ {
1443   // Empty Without Parens
1444   {
1445     (void)(*sv_ptr == nullptr) /* o1 */;
1446     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1447     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o1 */;
1448 
1449     (void)(*sv_ptr == (nullptr)) /* o2 */;
1450     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1451     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o2 */;
1452 
1453     (void)(nullptr == *sv_ptr) /* o3 */;
1454     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1455     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o3 */;
1456 
1457     (void)((nullptr) == *sv_ptr) /* o4 */;
1458     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1459     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o4 */;
1460   }
1461 
1462   // Empty With Parens
1463   {
1464     (void)((*sv_ptr) == nullptr) /* o5 */;
1465     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1466     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o5 */;
1467 
1468     (void)((*sv_ptr) == (nullptr)) /* o6 */;
1469     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1470     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o6 */;
1471 
1472     (void)(nullptr == (*sv_ptr)) /* o7 */;
1473     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1474     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o7 */;
1475 
1476     (void)((nullptr) == (*sv_ptr)) /* o8 */;
1477     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1478     // CHECK-FIXES: {{^}}    (void)(sv_ptr->empty()) /* o8 */;
1479   }
1480 
1481   // Non-Empty With Parens
1482   {
1483     (void)((*sv_ptr) != nullptr) /* o9 */;
1484     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1485     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o9 */;
1486 
1487     (void)((*sv_ptr) != (nullptr)) /* o10 */;
1488     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1489     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o10 */;
1490 
1491     (void)(nullptr != (*sv_ptr)) /* o11 */;
1492     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1493     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o11 */;
1494 
1495     (void)((nullptr) != (*sv_ptr)) /* o12 */;
1496     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1497     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o12 */;
1498   }
1499 
1500   // Non-Empty Without Parens
1501   {
1502     (void)((*sv_ptr) != nullptr) /* o13 */;
1503     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1504     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o13 */;
1505 
1506     (void)((*sv_ptr) != (nullptr)) /* o14 */;
1507     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1508     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o14 */;
1509 
1510     (void)(nullptr != (*sv_ptr)) /* o15 */;
1511     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1512     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o15 */;
1513 
1514     (void)((nullptr) != (*sv_ptr)) /* o16 */;
1515     // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: comparing{{.*}}emptiness query
1516     // CHECK-FIXES: {{^}}    (void)(!sv_ptr->empty()) /* o16 */;
1517   }
1518 }
1519 
1520 void equality_comparison_with_temporary(std::string_view sv) /* p */ {
1521   (void)(sv == std::string_view(nullptr)) /* p1 */;
1522   // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
1523   // CHECK-FIXES: {{^}}  (void)(sv == std::string_view()) /* p1 */;
1524 
1525   (void)(sv == std::string_view{nullptr}) /* p2 */;
1526   // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: constructing{{.*}}default
1527   // CHECK-FIXES: {{^}}  (void)(sv == std::string_view{}) /* p2 */;
1528 
1529   (void)(sv == (std::string_view) nullptr) /* p3 */;
1530   // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
1531   // CHECK-FIXES: {{^}}  (void)(sv == (std::string_view) {}) /* p3 */;
1532 
1533   (void)(sv == (std::string_view){nullptr}) /* p4 */;
1534   // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: constructing{{.*}}default
1535   // CHECK-FIXES: {{^}}  (void)(sv == (std::string_view){}) /* p4 */;
1536 
1537   (void)(sv == static_cast<SV>(nullptr)) /* p5 */;
1538   // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: casting{{.*}}empty string
1539   // CHECK-FIXES: {{^}}  (void)(sv == static_cast<SV>("")) /* p5 */;
1540 }
1541 
1542 void return_statement() /* q */ {
1543   // Return Statement
1544   {
1545     []() -> SV { return nullptr; } /* q1 */;
1546     // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: constructing{{.*}}default
1547     // CHECK-FIXES: {{^}}    []() -> SV { return {}; } /* q1 */;
1548 
1549     []() -> SV { return (nullptr); } /* q2 */;
1550     // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: constructing{{.*}}default
1551     // CHECK-FIXES: {{^}}    []() -> SV { return {}; } /* q2 */;
1552 
1553     []() -> SV { return {nullptr}; } /* q3 */;
1554     // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: constructing{{.*}}default
1555     // CHECK-FIXES: {{^}}    []() -> SV { return {}; } /* q3 */;
1556 
1557     []() -> SV { return {(nullptr)}; } /* q4 */;
1558     // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: constructing{{.*}}default
1559     // CHECK-FIXES: {{^}}    []() -> SV { return {}; } /* q4 */;
1560 
1561     []() -> SV { return {{nullptr}}; } /* q5 */;
1562     // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: constructing{{.*}}default
1563     // CHECK-FIXES: {{^}}    []() -> SV { return {}; } /* q5 */;
1564 
1565     []() -> SV { return {{(nullptr)}}; } /* q6 */;
1566     // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: constructing{{.*}}default
1567     // CHECK-FIXES: {{^}}    []() -> SV { return {}; } /* q6 */;
1568 
1569     []() -> SV { return {{}}; } /* q7 */; // Default `const CharT*`
1570     // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: constructing{{.*}}default
1571     // CHECK-FIXES: {{^}}    []() -> SV { return {}; } /* q7 */;
1572   }
1573 
1574   // Return Statement With Temporary
1575   {
1576     []() -> SV { return SV(nullptr); } /* q8 */;
1577     // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: constructing{{.*}}default
1578     // CHECK-FIXES: {{^}}    []() -> SV { return SV(); } /* q8 */;
1579 
1580     []() -> SV { return SV{nullptr}; } /* q9 */;
1581     // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: constructing{{.*}}default
1582     // CHECK-FIXES: {{^}}    []() -> SV { return SV{}; } /* q9 */;
1583 
1584     []() -> SV { return (SV) nullptr; } /* q10 */;
1585     // CHECK-MESSAGES: :[[@LINE-1]]:30: warning: constructing{{.*}}default
1586     // CHECK-FIXES: {{^}}    []() -> SV { return (SV) {}; } /* q10 */;
1587 
1588     []() -> SV { return (SV){nullptr}; } /* q11 */;
1589     // CHECK-MESSAGES: :[[@LINE-1]]:30: warning: constructing{{.*}}default
1590     // CHECK-FIXES: {{^}}    []() -> SV { return (SV){}; } /* q11 */;
1591 
1592     []() -> SV { return static_cast<SV>(nullptr); } /* q12 */;
1593     // CHECK-MESSAGES: :[[@LINE-1]]:41: warning: casting{{.*}}empty string
1594     // CHECK-FIXES: {{^}}    []() -> SV { return static_cast<SV>(""); } /* q12 */;
1595   }
1596 }
1597 
1598 void constructor_invocation() /* r */ {
1599   struct AcceptsSV {
1600     explicit AcceptsSV(std::string_view) {}
1601   } r1(nullptr);
1602   // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: passing{{.*}}empty string
1603   // CHECK-FIXES: {{^}}  } r1("");
1604 
1605   (void)(AcceptsSV{nullptr}) /* r2 */;
1606   // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: passing{{.*}}empty string
1607   // CHECK-FIXES: {{^}}  (void)(AcceptsSV{""}) /* r2 */;
1608 
1609   AcceptsSV r3{nullptr};
1610   // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: passing{{.*}}empty string
1611   // CHECK-FIXES: {{^}}  AcceptsSV r3{""};
1612 }
1613