1 //===-- lib/Semantics/check-io.cpp ----------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "check-io.h"
10 #include "flang/Common/format.h"
11 #include "flang/Parser/tools.h"
12 #include "flang/Semantics/expression.h"
13 #include "flang/Semantics/tools.h"
14 #include <unordered_map>
15 
16 namespace Fortran::semantics {
17 
18 // TODO: C1234, C1235 -- defined I/O constraints
19 
20 class FormatErrorReporter {
21 public:
22   FormatErrorReporter(SemanticsContext &context,
23       const parser::CharBlock &formatCharBlock, int errorAllowance = 3)
24       : context_{context}, formatCharBlock_{formatCharBlock},
25         errorAllowance_{errorAllowance} {}
26 
27   bool Say(const common::FormatMessage &);
28 
29 private:
30   SemanticsContext &context_;
31   const parser::CharBlock &formatCharBlock_;
32   int errorAllowance_; // initialized to maximum number of errors to report
33 };
34 
35 bool FormatErrorReporter::Say(const common::FormatMessage &msg) {
36   if (!msg.isError && !context_.warnOnNonstandardUsage()) {
37     return false;
38   }
39   parser::MessageFormattedText text{
40       parser::MessageFixedText(msg.text, strlen(msg.text), msg.isError),
41       msg.arg};
42   if (formatCharBlock_.size()) {
43     // The input format is a folded expression.  Error markers span the full
44     // original unfolded expression in formatCharBlock_.
45     context_.Say(formatCharBlock_, text);
46   } else {
47     // The input format is a source expression.  Error markers have an offset
48     // and length relative to the beginning of formatCharBlock_.
49     parser::CharBlock messageCharBlock{
50         parser::CharBlock(formatCharBlock_.begin() + msg.offset, msg.length)};
51     context_.Say(messageCharBlock, text);
52   }
53   return msg.isError && --errorAllowance_ <= 0;
54 }
55 
56 void IoChecker::Enter(
57     const parser::Statement<common::Indirection<parser::FormatStmt>> &stmt) {
58   if (!stmt.label) {
59     context_.Say("Format statement must be labeled"_err_en_US); // C1301
60   }
61   const char *formatStart{static_cast<const char *>(
62       std::memchr(stmt.source.begin(), '(', stmt.source.size()))};
63   parser::CharBlock reporterCharBlock{formatStart, static_cast<std::size_t>(0)};
64   FormatErrorReporter reporter{context_, reporterCharBlock};
65   auto reporterWrapper{[&](const auto &msg) { return reporter.Say(msg); }};
66   switch (context_.GetDefaultKind(TypeCategory::Character)) {
67   case 1: {
68     common::FormatValidator<char> validator{formatStart,
69         stmt.source.size() - (formatStart - stmt.source.begin()),
70         reporterWrapper};
71     validator.Check();
72     break;
73   }
74   case 2: { // TODO: Get this to work.
75     common::FormatValidator<char16_t> validator{
76         /*???*/ nullptr, /*???*/ 0, reporterWrapper};
77     validator.Check();
78     break;
79   }
80   case 4: { // TODO: Get this to work.
81     common::FormatValidator<char32_t> validator{
82         /*???*/ nullptr, /*???*/ 0, reporterWrapper};
83     validator.Check();
84     break;
85   }
86   default:
87     CRASH_NO_CASE;
88   }
89 }
90 
91 void IoChecker::Enter(const parser::ConnectSpec &spec) {
92   // ConnectSpec context FileNameExpr
93   if (std::get_if<parser::FileNameExpr>(&spec.u)) {
94     SetSpecifier(IoSpecKind::File);
95   }
96 }
97 
98 void IoChecker::Enter(const parser::ConnectSpec::CharExpr &spec) {
99   IoSpecKind specKind{};
100   using ParseKind = parser::ConnectSpec::CharExpr::Kind;
101   switch (std::get<ParseKind>(spec.t)) {
102   case ParseKind::Access:
103     specKind = IoSpecKind::Access;
104     break;
105   case ParseKind::Action:
106     specKind = IoSpecKind::Action;
107     break;
108   case ParseKind::Asynchronous:
109     specKind = IoSpecKind::Asynchronous;
110     break;
111   case ParseKind::Blank:
112     specKind = IoSpecKind::Blank;
113     break;
114   case ParseKind::Decimal:
115     specKind = IoSpecKind::Decimal;
116     break;
117   case ParseKind::Delim:
118     specKind = IoSpecKind::Delim;
119     break;
120   case ParseKind::Encoding:
121     specKind = IoSpecKind::Encoding;
122     break;
123   case ParseKind::Form:
124     specKind = IoSpecKind::Form;
125     break;
126   case ParseKind::Pad:
127     specKind = IoSpecKind::Pad;
128     break;
129   case ParseKind::Position:
130     specKind = IoSpecKind::Position;
131     break;
132   case ParseKind::Round:
133     specKind = IoSpecKind::Round;
134     break;
135   case ParseKind::Sign:
136     specKind = IoSpecKind::Sign;
137     break;
138   case ParseKind::Convert:
139     specKind = IoSpecKind::Convert;
140     break;
141   case ParseKind::Dispose:
142     specKind = IoSpecKind::Dispose;
143     break;
144   }
145   SetSpecifier(specKind);
146   if (const std::optional<std::string> charConst{GetConstExpr<std::string>(
147           std::get<parser::ScalarDefaultCharExpr>(spec.t))}) {
148     std::string s{parser::ToUpperCaseLetters(*charConst)};
149     if (specKind == IoSpecKind::Access) {
150       flags_.set(Flag::KnownAccess);
151       flags_.set(Flag::AccessDirect, s == "DIRECT");
152       flags_.set(Flag::AccessStream, s == "STREAM");
153     }
154     CheckStringValue(specKind, *charConst, parser::FindSourceLocation(spec));
155   }
156 }
157 
158 void IoChecker::Enter(const parser::ConnectSpec::Newunit &) {
159   SetSpecifier(IoSpecKind::Newunit);
160 }
161 
162 void IoChecker::Enter(const parser::ConnectSpec::Recl &spec) {
163   SetSpecifier(IoSpecKind::Recl);
164   if (const std::optional<std::int64_t> recl{
165           GetConstExpr<std::int64_t>(spec)}) {
166     if (*recl <= 0) {
167       context_.Say(parser::FindSourceLocation(spec),
168           "RECL value (%jd) must be positive"_err_en_US,
169           *recl); // 12.5.6.15
170     }
171   }
172 }
173 
174 void IoChecker::Enter(const parser::EndLabel &) {
175   SetSpecifier(IoSpecKind::End);
176 }
177 
178 void IoChecker::Enter(const parser::EorLabel &) {
179   SetSpecifier(IoSpecKind::Eor);
180 }
181 
182 void IoChecker::Enter(const parser::ErrLabel &) {
183   SetSpecifier(IoSpecKind::Err);
184 }
185 
186 void IoChecker::Enter(const parser::FileUnitNumber &) {
187   SetSpecifier(IoSpecKind::Unit);
188   flags_.set(Flag::NumberUnit);
189 }
190 
191 void IoChecker::Enter(const parser::Format &spec) {
192   SetSpecifier(IoSpecKind::Fmt);
193   flags_.set(Flag::FmtOrNml);
194   std::visit(
195       common::visitors{
196           [&](const parser::Label &) { flags_.set(Flag::LabelFmt); },
197           [&](const parser::Star &) { flags_.set(Flag::StarFmt); },
198           [&](const parser::Expr &format) {
199             const SomeExpr *expr{GetExpr(format)};
200             if (!expr) {
201               return;
202             }
203             auto type{expr->GetType()};
204             if (!type ||
205                 (type->category() != TypeCategory::Integer &&
206                     type->category() != TypeCategory::Character) ||
207                 type->kind() !=
208                     context_.defaultKinds().GetDefaultKind(type->category())) {
209               context_.Say(format.source,
210                   "Format expression must be default character or integer"_err_en_US);
211               return;
212             }
213             if (type->category() == TypeCategory::Integer) {
214               flags_.set(Flag::AssignFmt);
215               if (expr->Rank() != 0 || !IsVariable(*expr)) {
216                 context_.Say(format.source,
217                     "Assigned format label must be a scalar variable"_err_en_US);
218               }
219               return;
220             }
221             flags_.set(Flag::CharFmt);
222             const std::optional<std::string> constantFormat{
223                 GetConstExpr<std::string>(format)};
224             if (!constantFormat) {
225               return;
226             }
227             // validate constant format -- 12.6.2.2
228             bool isFolded{constantFormat->size() != format.source.size() - 2};
229             parser::CharBlock reporterCharBlock{isFolded
230                     ? parser::CharBlock{format.source}
231                     : parser::CharBlock{format.source.begin() + 1,
232                           static_cast<std::size_t>(0)}};
233             FormatErrorReporter reporter{context_, reporterCharBlock};
234             auto reporterWrapper{
235                 [&](const auto &msg) { return reporter.Say(msg); }};
236             switch (context_.GetDefaultKind(TypeCategory::Character)) {
237             case 1: {
238               common::FormatValidator<char> validator{constantFormat->c_str(),
239                   constantFormat->length(), reporterWrapper, stmt_};
240               validator.Check();
241               break;
242             }
243             case 2: {
244               // TODO: Get this to work.  (Maybe combine with earlier instance?)
245               common::FormatValidator<char16_t> validator{
246                   /*???*/ nullptr, /*???*/ 0, reporterWrapper, stmt_};
247               validator.Check();
248               break;
249             }
250             case 4: {
251               // TODO: Get this to work.  (Maybe combine with earlier instance?)
252               common::FormatValidator<char32_t> validator{
253                   /*???*/ nullptr, /*???*/ 0, reporterWrapper, stmt_};
254               validator.Check();
255               break;
256             }
257             default:
258               CRASH_NO_CASE;
259             }
260           },
261       },
262       spec.u);
263 }
264 
265 void IoChecker::Enter(const parser::IdExpr &) { SetSpecifier(IoSpecKind::Id); }
266 
267 void IoChecker::Enter(const parser::IdVariable &spec) {
268   SetSpecifier(IoSpecKind::Id);
269   auto expr{GetExpr(spec)};
270   if (!expr || !expr->GetType()) {
271     return;
272   }
273   int kind{expr->GetType()->kind()};
274   int defaultKind{context_.GetDefaultKind(TypeCategory::Integer)};
275   if (kind < defaultKind) {
276     context_.Say(
277         "ID kind (%d) is smaller than default INTEGER kind (%d)"_err_en_US,
278         std::move(kind), std::move(defaultKind)); // C1229
279   }
280 }
281 
282 void IoChecker::Enter(const parser::InputItem &spec) {
283   flags_.set(Flag::DataList);
284   if (const parser::Variable * var{std::get_if<parser::Variable>(&spec.u)}) {
285     const parser::Name &name{GetLastName(*var)};
286     if (auto *details{name.symbol->detailsIf<ObjectEntityDetails>()}) {
287       // TODO: Determine if this check is needed at all, and if so, replace
288       // the false subcondition with a check for a whole array.  Otherwise,
289       // the check incorrectly flags array element and section references.
290       if (details->IsAssumedSize() && false) {
291         // This check may be superseded by C928 or C1002.
292         context_.Say(name.source,
293             "'%s' must not be a whole assumed size array"_err_en_US,
294             name.source); // C1231
295       }
296     }
297   }
298 }
299 
300 void IoChecker::Enter(const parser::InquireSpec &spec) {
301   // InquireSpec context FileNameExpr
302   if (std::get_if<parser::FileNameExpr>(&spec.u)) {
303     SetSpecifier(IoSpecKind::File);
304   }
305 }
306 
307 void IoChecker::Enter(const parser::InquireSpec::CharVar &spec) {
308   IoSpecKind specKind{};
309   using ParseKind = parser::InquireSpec::CharVar::Kind;
310   switch (std::get<ParseKind>(spec.t)) {
311   case ParseKind::Access:
312     specKind = IoSpecKind::Access;
313     break;
314   case ParseKind::Action:
315     specKind = IoSpecKind::Action;
316     break;
317   case ParseKind::Asynchronous:
318     specKind = IoSpecKind::Asynchronous;
319     break;
320   case ParseKind::Blank:
321     specKind = IoSpecKind::Blank;
322     break;
323   case ParseKind::Decimal:
324     specKind = IoSpecKind::Decimal;
325     break;
326   case ParseKind::Delim:
327     specKind = IoSpecKind::Delim;
328     break;
329   case ParseKind::Direct:
330     specKind = IoSpecKind::Direct;
331     break;
332   case ParseKind::Encoding:
333     specKind = IoSpecKind::Encoding;
334     break;
335   case ParseKind::Form:
336     specKind = IoSpecKind::Form;
337     break;
338   case ParseKind::Formatted:
339     specKind = IoSpecKind::Formatted;
340     break;
341   case ParseKind::Iomsg:
342     specKind = IoSpecKind::Iomsg;
343     break;
344   case ParseKind::Name:
345     specKind = IoSpecKind::Name;
346     break;
347   case ParseKind::Pad:
348     specKind = IoSpecKind::Pad;
349     break;
350   case ParseKind::Position:
351     specKind = IoSpecKind::Position;
352     break;
353   case ParseKind::Read:
354     specKind = IoSpecKind::Read;
355     break;
356   case ParseKind::Readwrite:
357     specKind = IoSpecKind::Readwrite;
358     break;
359   case ParseKind::Round:
360     specKind = IoSpecKind::Round;
361     break;
362   case ParseKind::Sequential:
363     specKind = IoSpecKind::Sequential;
364     break;
365   case ParseKind::Sign:
366     specKind = IoSpecKind::Sign;
367     break;
368   case ParseKind::Status:
369     specKind = IoSpecKind::Status;
370     break;
371   case ParseKind::Stream:
372     specKind = IoSpecKind::Stream;
373     break;
374   case ParseKind::Unformatted:
375     specKind = IoSpecKind::Unformatted;
376     break;
377   case ParseKind::Write:
378     specKind = IoSpecKind::Write;
379     break;
380   case ParseKind::Convert:
381     specKind = IoSpecKind::Convert;
382     break;
383   case ParseKind::Dispose:
384     specKind = IoSpecKind::Dispose;
385     break;
386   }
387   SetSpecifier(specKind);
388 }
389 
390 void IoChecker::Enter(const parser::InquireSpec::IntVar &spec) {
391   IoSpecKind specKind{};
392   using ParseKind = parser::InquireSpec::IntVar::Kind;
393   switch (std::get<parser::InquireSpec::IntVar::Kind>(spec.t)) {
394   case ParseKind::Iostat:
395     specKind = IoSpecKind::Iostat;
396     break;
397   case ParseKind::Nextrec:
398     specKind = IoSpecKind::Nextrec;
399     break;
400   case ParseKind::Number:
401     specKind = IoSpecKind::Number;
402     break;
403   case ParseKind::Pos:
404     specKind = IoSpecKind::Pos;
405     break;
406   case ParseKind::Recl:
407     specKind = IoSpecKind::Recl;
408     break;
409   case ParseKind::Size:
410     specKind = IoSpecKind::Size;
411     break;
412   }
413   SetSpecifier(specKind);
414 }
415 
416 void IoChecker::Enter(const parser::InquireSpec::LogVar &spec) {
417   IoSpecKind specKind{};
418   using ParseKind = parser::InquireSpec::LogVar::Kind;
419   switch (std::get<parser::InquireSpec::LogVar::Kind>(spec.t)) {
420   case ParseKind::Exist:
421     specKind = IoSpecKind::Exist;
422     break;
423   case ParseKind::Named:
424     specKind = IoSpecKind::Named;
425     break;
426   case ParseKind::Opened:
427     specKind = IoSpecKind::Opened;
428     break;
429   case ParseKind::Pending:
430     specKind = IoSpecKind::Pending;
431     break;
432   }
433   SetSpecifier(specKind);
434 }
435 
436 void IoChecker::Enter(const parser::IoControlSpec &spec) {
437   // IoControlSpec context Name
438   flags_.set(Flag::IoControlList);
439   if (std::holds_alternative<parser::Name>(spec.u)) {
440     SetSpecifier(IoSpecKind::Nml);
441     flags_.set(Flag::FmtOrNml);
442   }
443 }
444 
445 void IoChecker::Enter(const parser::IoControlSpec::Asynchronous &spec) {
446   SetSpecifier(IoSpecKind::Asynchronous);
447   if (const std::optional<std::string> charConst{
448           GetConstExpr<std::string>(spec)}) {
449     flags_.set(
450         Flag::AsynchronousYes, parser::ToUpperCaseLetters(*charConst) == "YES");
451     CheckStringValue(IoSpecKind::Asynchronous, *charConst,
452         parser::FindSourceLocation(spec)); // C1223
453   }
454 }
455 
456 void IoChecker::Enter(const parser::IoControlSpec::CharExpr &spec) {
457   IoSpecKind specKind{};
458   using ParseKind = parser::IoControlSpec::CharExpr::Kind;
459   switch (std::get<ParseKind>(spec.t)) {
460   case ParseKind::Advance:
461     specKind = IoSpecKind::Advance;
462     break;
463   case ParseKind::Blank:
464     specKind = IoSpecKind::Blank;
465     break;
466   case ParseKind::Decimal:
467     specKind = IoSpecKind::Decimal;
468     break;
469   case ParseKind::Delim:
470     specKind = IoSpecKind::Delim;
471     break;
472   case ParseKind::Pad:
473     specKind = IoSpecKind::Pad;
474     break;
475   case ParseKind::Round:
476     specKind = IoSpecKind::Round;
477     break;
478   case ParseKind::Sign:
479     specKind = IoSpecKind::Sign;
480     break;
481   }
482   SetSpecifier(specKind);
483   if (const std::optional<std::string> charConst{GetConstExpr<std::string>(
484           std::get<parser::ScalarDefaultCharExpr>(spec.t))}) {
485     if (specKind == IoSpecKind::Advance) {
486       flags_.set(
487           Flag::AdvanceYes, parser::ToUpperCaseLetters(*charConst) == "YES");
488     }
489     CheckStringValue(specKind, *charConst, parser::FindSourceLocation(spec));
490   }
491 }
492 
493 void IoChecker::Enter(const parser::IoControlSpec::Pos &) {
494   SetSpecifier(IoSpecKind::Pos);
495 }
496 
497 void IoChecker::Enter(const parser::IoControlSpec::Rec &) {
498   SetSpecifier(IoSpecKind::Rec);
499 }
500 
501 void IoChecker::Enter(const parser::IoControlSpec::Size &) {
502   SetSpecifier(IoSpecKind::Size);
503 }
504 
505 void IoChecker::Enter(const parser::IoUnit &spec) {
506   if (const parser::Variable * var{std::get_if<parser::Variable>(&spec.u)}) {
507     // TODO: C1201 - internal file variable must not be an array section ...
508     if (auto expr{GetExpr(*var)}) {
509       if (!ExprTypeKindIsDefault(*expr, context_)) {
510         // This may be too restrictive; other kinds may be valid.
511         context_.Say( // C1202
512             "Invalid character kind for an internal file variable"_err_en_US);
513       }
514     }
515     SetSpecifier(IoSpecKind::Unit);
516     flags_.set(Flag::InternalUnit);
517   } else if (std::get_if<parser::Star>(&spec.u)) {
518     SetSpecifier(IoSpecKind::Unit);
519     flags_.set(Flag::StarUnit);
520   }
521 }
522 
523 void IoChecker::Enter(const parser::MsgVariable &) {
524   SetSpecifier(IoSpecKind::Iomsg);
525 }
526 
527 void IoChecker::Enter(const parser::OutputItem &) {
528   flags_.set(Flag::DataList);
529   // TODO: C1233 - output item must not be a procedure pointer
530 }
531 
532 void IoChecker::Enter(const parser::StatusExpr &spec) {
533   SetSpecifier(IoSpecKind::Status);
534   if (const std::optional<std::string> charConst{
535           GetConstExpr<std::string>(spec)}) {
536     // Status values for Open and Close are different.
537     std::string s{parser::ToUpperCaseLetters(*charConst)};
538     if (stmt_ == IoStmtKind::Open) {
539       flags_.set(Flag::KnownStatus);
540       flags_.set(Flag::StatusNew, s == "NEW");
541       flags_.set(Flag::StatusReplace, s == "REPLACE");
542       flags_.set(Flag::StatusScratch, s == "SCRATCH");
543       // CheckStringValue compares for OPEN Status string values.
544       CheckStringValue(
545           IoSpecKind::Status, *charConst, parser::FindSourceLocation(spec));
546       return;
547     }
548     CHECK(stmt_ == IoStmtKind::Close);
549     if (s != "DELETE" && s != "KEEP") {
550       context_.Say(parser::FindSourceLocation(spec),
551           "Invalid STATUS value '%s'"_err_en_US, *charConst);
552     }
553   }
554 }
555 
556 void IoChecker::Enter(const parser::StatVariable &) {
557   if (stmt_ == IoStmtKind::None) {
558     // ALLOCATE & DEALLOCATE
559   } else {
560     SetSpecifier(IoSpecKind::Iostat);
561   }
562 }
563 
564 void IoChecker::Leave(const parser::BackspaceStmt &) {
565   CheckForPureSubprogram();
566   CheckForRequiredSpecifier(
567       flags_.test(Flag::NumberUnit), "UNIT number"); // C1240
568   Done();
569 }
570 
571 void IoChecker::Leave(const parser::CloseStmt &) {
572   CheckForPureSubprogram();
573   CheckForRequiredSpecifier(
574       flags_.test(Flag::NumberUnit), "UNIT number"); // C1208
575   Done();
576 }
577 
578 void IoChecker::Leave(const parser::EndfileStmt &) {
579   CheckForPureSubprogram();
580   CheckForRequiredSpecifier(
581       flags_.test(Flag::NumberUnit), "UNIT number"); // C1240
582   Done();
583 }
584 
585 void IoChecker::Leave(const parser::FlushStmt &) {
586   CheckForPureSubprogram();
587   CheckForRequiredSpecifier(
588       flags_.test(Flag::NumberUnit), "UNIT number"); // C1243
589   Done();
590 }
591 
592 void IoChecker::Leave(const parser::InquireStmt &stmt) {
593   if (std::get_if<std::list<parser::InquireSpec>>(&stmt.u)) {
594     CheckForPureSubprogram();
595     // Inquire by unit or by file (vs. by output list).
596     CheckForRequiredSpecifier(
597         flags_.test(Flag::NumberUnit) || specifierSet_.test(IoSpecKind::File),
598         "UNIT number or FILE"); // C1246
599     CheckForProhibitedSpecifier(IoSpecKind::File, IoSpecKind::Unit); // C1246
600     CheckForRequiredSpecifier(IoSpecKind::Id, IoSpecKind::Pending); // C1248
601   }
602   Done();
603 }
604 
605 void IoChecker::Leave(const parser::OpenStmt &) {
606   CheckForPureSubprogram();
607   CheckForRequiredSpecifier(specifierSet_.test(IoSpecKind::Unit) ||
608           specifierSet_.test(IoSpecKind::Newunit),
609       "UNIT or NEWUNIT"); // C1204, C1205
610   CheckForProhibitedSpecifier(
611       IoSpecKind::Newunit, IoSpecKind::Unit); // C1204, C1205
612   CheckForRequiredSpecifier(flags_.test(Flag::StatusNew), "STATUS='NEW'",
613       IoSpecKind::File); // 12.5.6.10
614   CheckForRequiredSpecifier(flags_.test(Flag::StatusReplace),
615       "STATUS='REPLACE'", IoSpecKind::File); // 12.5.6.10
616   CheckForProhibitedSpecifier(flags_.test(Flag::StatusScratch),
617       "STATUS='SCRATCH'", IoSpecKind::File); // 12.5.6.10
618   if (flags_.test(Flag::KnownStatus)) {
619     CheckForRequiredSpecifier(IoSpecKind::Newunit,
620         specifierSet_.test(IoSpecKind::File) ||
621             flags_.test(Flag::StatusScratch),
622         "FILE or STATUS='SCRATCH'"); // 12.5.6.12
623   } else {
624     CheckForRequiredSpecifier(IoSpecKind::Newunit,
625         specifierSet_.test(IoSpecKind::File) ||
626             specifierSet_.test(IoSpecKind::Status),
627         "FILE or STATUS"); // 12.5.6.12
628   }
629   if (flags_.test(Flag::KnownAccess)) {
630     CheckForRequiredSpecifier(flags_.test(Flag::AccessDirect),
631         "ACCESS='DIRECT'", IoSpecKind::Recl); // 12.5.6.15
632     CheckForProhibitedSpecifier(flags_.test(Flag::AccessStream),
633         "STATUS='STREAM'", IoSpecKind::Recl); // 12.5.6.15
634   }
635   Done();
636 }
637 
638 void IoChecker::Leave(const parser::PrintStmt &) {
639   CheckForPureSubprogram();
640   Done();
641 }
642 
643 static void CheckForDoVariableInNamelist(const Symbol &namelist,
644     SemanticsContext &context, parser::CharBlock namelistLocation) {
645   const auto &details{namelist.GetUltimate().get<NamelistDetails>()};
646   for (const Symbol &object : details.objects()) {
647     context.CheckIndexVarRedefine(namelistLocation, object);
648   }
649 }
650 
651 static void CheckForDoVariableInNamelistSpec(
652     const parser::ReadStmt &readStmt, SemanticsContext &context) {
653   const std::list<parser::IoControlSpec> &controls{readStmt.controls};
654   for (const auto &control : controls) {
655     if (const auto *namelist{std::get_if<parser::Name>(&control.u)}) {
656       if (const Symbol * symbol{namelist->symbol}) {
657         CheckForDoVariableInNamelist(*symbol, context, namelist->source);
658       }
659     }
660   }
661 }
662 
663 static void CheckForDoVariable(
664     const parser::ReadStmt &readStmt, SemanticsContext &context) {
665   CheckForDoVariableInNamelistSpec(readStmt, context);
666   const std::list<parser::InputItem> &items{readStmt.items};
667   for (const auto &item : items) {
668     if (const parser::Variable *
669         variable{std::get_if<parser::Variable>(&item.u)}) {
670       context.CheckIndexVarRedefine(*variable);
671     }
672   }
673 }
674 
675 void IoChecker::Leave(const parser::ReadStmt &readStmt) {
676   if (!flags_.test(Flag::InternalUnit)) {
677     CheckForPureSubprogram();
678   }
679   CheckForDoVariable(readStmt, context_);
680   if (!flags_.test(Flag::IoControlList)) {
681     Done();
682     return;
683   }
684   LeaveReadWrite();
685   CheckForProhibitedSpecifier(IoSpecKind::Delim); // C1212
686   CheckForProhibitedSpecifier(IoSpecKind::Sign); // C1212
687   CheckForProhibitedSpecifier(IoSpecKind::Rec, IoSpecKind::End); // C1220
688   CheckForRequiredSpecifier(IoSpecKind::Eor,
689       specifierSet_.test(IoSpecKind::Advance) && !flags_.test(Flag::AdvanceYes),
690       "ADVANCE with value 'NO'"); // C1222 + 12.6.2.1p2
691   CheckForRequiredSpecifier(IoSpecKind::Blank, flags_.test(Flag::FmtOrNml),
692       "FMT or NML"); // C1227
693   CheckForRequiredSpecifier(
694       IoSpecKind::Pad, flags_.test(Flag::FmtOrNml), "FMT or NML"); // C1227
695   Done();
696 }
697 
698 void IoChecker::Leave(const parser::RewindStmt &) {
699   CheckForRequiredSpecifier(
700       flags_.test(Flag::NumberUnit), "UNIT number"); // C1240
701   CheckForPureSubprogram();
702   Done();
703 }
704 
705 void IoChecker::Leave(const parser::WaitStmt &) {
706   CheckForRequiredSpecifier(
707       flags_.test(Flag::NumberUnit), "UNIT number"); // C1237
708   CheckForPureSubprogram();
709   Done();
710 }
711 
712 void IoChecker::Leave(const parser::WriteStmt &) {
713   if (!flags_.test(Flag::InternalUnit)) {
714     CheckForPureSubprogram();
715   }
716   LeaveReadWrite();
717   CheckForProhibitedSpecifier(IoSpecKind::Blank); // C1213
718   CheckForProhibitedSpecifier(IoSpecKind::End); // C1213
719   CheckForProhibitedSpecifier(IoSpecKind::Eor); // C1213
720   CheckForProhibitedSpecifier(IoSpecKind::Pad); // C1213
721   CheckForProhibitedSpecifier(IoSpecKind::Size); // C1213
722   CheckForRequiredSpecifier(
723       IoSpecKind::Sign, flags_.test(Flag::FmtOrNml), "FMT or NML"); // C1227
724   CheckForRequiredSpecifier(IoSpecKind::Delim,
725       flags_.test(Flag::StarFmt) || specifierSet_.test(IoSpecKind::Nml),
726       "FMT=* or NML"); // C1228
727   Done();
728 }
729 
730 void IoChecker::LeaveReadWrite() const {
731   CheckForRequiredSpecifier(IoSpecKind::Unit); // C1211
732   CheckForProhibitedSpecifier(IoSpecKind::Nml, IoSpecKind::Rec); // C1216
733   CheckForProhibitedSpecifier(IoSpecKind::Nml, IoSpecKind::Fmt); // C1216
734   CheckForProhibitedSpecifier(
735       IoSpecKind::Nml, flags_.test(Flag::DataList), "a data list"); // C1216
736   CheckForProhibitedSpecifier(flags_.test(Flag::InternalUnit),
737       "UNIT=internal-file", IoSpecKind::Pos); // C1219
738   CheckForProhibitedSpecifier(flags_.test(Flag::InternalUnit),
739       "UNIT=internal-file", IoSpecKind::Rec); // C1219
740   CheckForProhibitedSpecifier(
741       flags_.test(Flag::StarUnit), "UNIT=*", IoSpecKind::Pos); // C1219
742   CheckForProhibitedSpecifier(
743       flags_.test(Flag::StarUnit), "UNIT=*", IoSpecKind::Rec); // C1219
744   CheckForProhibitedSpecifier(
745       IoSpecKind::Rec, flags_.test(Flag::StarFmt), "FMT=*"); // C1220
746   CheckForRequiredSpecifier(IoSpecKind::Advance,
747       flags_.test(Flag::CharFmt) || flags_.test(Flag::LabelFmt) ||
748           flags_.test(Flag::AssignFmt),
749       "an explicit format"); // C1221
750   CheckForProhibitedSpecifier(IoSpecKind::Advance,
751       flags_.test(Flag::InternalUnit), "UNIT=internal-file"); // C1221
752   CheckForRequiredSpecifier(flags_.test(Flag::AsynchronousYes),
753       "ASYNCHRONOUS='YES'", flags_.test(Flag::NumberUnit),
754       "UNIT=number"); // C1224
755   CheckForRequiredSpecifier(IoSpecKind::Id, flags_.test(Flag::AsynchronousYes),
756       "ASYNCHRONOUS='YES'"); // C1225
757   CheckForProhibitedSpecifier(IoSpecKind::Pos, IoSpecKind::Rec); // C1226
758   CheckForRequiredSpecifier(IoSpecKind::Decimal, flags_.test(Flag::FmtOrNml),
759       "FMT or NML"); // C1227
760   CheckForRequiredSpecifier(IoSpecKind::Round, flags_.test(Flag::FmtOrNml),
761       "FMT or NML"); // C1227
762 }
763 
764 void IoChecker::SetSpecifier(IoSpecKind specKind) {
765   if (stmt_ == IoStmtKind::None) {
766     // FMT may appear on PRINT statements, which don't have any checks.
767     // [IO]MSG and [IO]STAT parse symbols are shared with non-I/O statements.
768     return;
769   }
770   // C1203, C1207, C1210, C1236, C1239, C1242, C1245
771   if (specifierSet_.test(specKind)) {
772     context_.Say("Duplicate %s specifier"_err_en_US,
773         parser::ToUpperCaseLetters(common::EnumToString(specKind)));
774   }
775   specifierSet_.set(specKind);
776 }
777 
778 void IoChecker::CheckStringValue(IoSpecKind specKind, const std::string &value,
779     const parser::CharBlock &source) const {
780   static std::unordered_map<IoSpecKind, const std::set<std::string>> specValues{
781       {IoSpecKind::Access, {"DIRECT", "SEQUENTIAL", "STREAM"}},
782       {IoSpecKind::Action, {"READ", "READWRITE", "WRITE"}},
783       {IoSpecKind::Advance, {"NO", "YES"}},
784       {IoSpecKind::Asynchronous, {"NO", "YES"}},
785       {IoSpecKind::Blank, {"NULL", "ZERO"}},
786       {IoSpecKind::Decimal, {"COMMA", "POINT"}},
787       {IoSpecKind::Delim, {"APOSTROPHE", "NONE", "QUOTE"}},
788       {IoSpecKind::Encoding, {"DEFAULT", "UTF-8"}},
789       {IoSpecKind::Form, {"FORMATTED", "UNFORMATTED"}},
790       {IoSpecKind::Pad, {"NO", "YES"}},
791       {IoSpecKind::Position, {"APPEND", "ASIS", "REWIND"}},
792       {IoSpecKind::Round,
793           {"COMPATIBLE", "DOWN", "NEAREST", "PROCESSOR_DEFINED", "UP", "ZERO"}},
794       {IoSpecKind::Sign, {"PLUS", "PROCESSOR_DEFINED", "SUPPRESS"}},
795       {IoSpecKind::Status,
796           // Open values; Close values are {"DELETE", "KEEP"}.
797           {"NEW", "OLD", "REPLACE", "SCRATCH", "UNKNOWN"}},
798       {IoSpecKind::Convert, {"BIG_ENDIAN", "LITTLE_ENDIAN", "NATIVE"}},
799       {IoSpecKind::Dispose, {"DELETE", "KEEP"}},
800   };
801   if (!specValues.at(specKind).count(parser::ToUpperCaseLetters(value))) {
802     context_.Say(source, "Invalid %s value '%s'"_err_en_US,
803         parser::ToUpperCaseLetters(common::EnumToString(specKind)), value);
804   }
805 }
806 
807 // CheckForRequiredSpecifier and CheckForProhibitedSpecifier functions
808 // need conditions to check, and string arguments to insert into a message.
809 // A IoSpecKind provides both an absence/presence condition and a string
810 // argument (its name).  A (condition, string) pair provides an arbitrary
811 // condition and an arbitrary string.
812 
813 void IoChecker::CheckForRequiredSpecifier(IoSpecKind specKind) const {
814   if (!specifierSet_.test(specKind)) {
815     context_.Say("%s statement must have a %s specifier"_err_en_US,
816         parser::ToUpperCaseLetters(common::EnumToString(stmt_)),
817         parser::ToUpperCaseLetters(common::EnumToString(specKind)));
818   }
819 }
820 
821 void IoChecker::CheckForRequiredSpecifier(
822     bool condition, const std::string &s) const {
823   if (!condition) {
824     context_.Say("%s statement must have a %s specifier"_err_en_US,
825         parser::ToUpperCaseLetters(common::EnumToString(stmt_)), s);
826   }
827 }
828 
829 void IoChecker::CheckForRequiredSpecifier(
830     IoSpecKind specKind1, IoSpecKind specKind2) const {
831   if (specifierSet_.test(specKind1) && !specifierSet_.test(specKind2)) {
832     context_.Say("If %s appears, %s must also appear"_err_en_US,
833         parser::ToUpperCaseLetters(common::EnumToString(specKind1)),
834         parser::ToUpperCaseLetters(common::EnumToString(specKind2)));
835   }
836 }
837 
838 void IoChecker::CheckForRequiredSpecifier(
839     IoSpecKind specKind, bool condition, const std::string &s) const {
840   if (specifierSet_.test(specKind) && !condition) {
841     context_.Say("If %s appears, %s must also appear"_err_en_US,
842         parser::ToUpperCaseLetters(common::EnumToString(specKind)), s);
843   }
844 }
845 
846 void IoChecker::CheckForRequiredSpecifier(
847     bool condition, const std::string &s, IoSpecKind specKind) const {
848   if (condition && !specifierSet_.test(specKind)) {
849     context_.Say("If %s appears, %s must also appear"_err_en_US, s,
850         parser::ToUpperCaseLetters(common::EnumToString(specKind)));
851   }
852 }
853 
854 void IoChecker::CheckForRequiredSpecifier(bool condition1,
855     const std::string &s1, bool condition2, const std::string &s2) const {
856   if (condition1 && !condition2) {
857     context_.Say("If %s appears, %s must also appear"_err_en_US, s1, s2);
858   }
859 }
860 
861 void IoChecker::CheckForProhibitedSpecifier(IoSpecKind specKind) const {
862   if (specifierSet_.test(specKind)) {
863     context_.Say("%s statement must not have a %s specifier"_err_en_US,
864         parser::ToUpperCaseLetters(common::EnumToString(stmt_)),
865         parser::ToUpperCaseLetters(common::EnumToString(specKind)));
866   }
867 }
868 
869 void IoChecker::CheckForProhibitedSpecifier(
870     IoSpecKind specKind1, IoSpecKind specKind2) const {
871   if (specifierSet_.test(specKind1) && specifierSet_.test(specKind2)) {
872     context_.Say("If %s appears, %s must not appear"_err_en_US,
873         parser::ToUpperCaseLetters(common::EnumToString(specKind1)),
874         parser::ToUpperCaseLetters(common::EnumToString(specKind2)));
875   }
876 }
877 
878 void IoChecker::CheckForProhibitedSpecifier(
879     IoSpecKind specKind, bool condition, const std::string &s) const {
880   if (specifierSet_.test(specKind) && condition) {
881     context_.Say("If %s appears, %s must not appear"_err_en_US,
882         parser::ToUpperCaseLetters(common::EnumToString(specKind)), s);
883   }
884 }
885 
886 void IoChecker::CheckForProhibitedSpecifier(
887     bool condition, const std::string &s, IoSpecKind specKind) const {
888   if (condition && specifierSet_.test(specKind)) {
889     context_.Say("If %s appears, %s must not appear"_err_en_US, s,
890         parser::ToUpperCaseLetters(common::EnumToString(specKind)));
891   }
892 }
893 
894 void IoChecker::CheckForPureSubprogram() const { // C1597
895   CHECK(context_.location());
896   if (FindPureProcedureContaining(context_.FindScope(*context_.location()))) {
897     context_.Say("External I/O is not allowed in a pure subprogram"_err_en_US);
898   }
899 }
900 
901 } // namespace Fortran::semantics
902