1 //===-- GlobalCompilationDatabaseTests.cpp ----------------------*- C++ -*-===//
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 "GlobalCompilationDatabase.h"
10 
11 #include "CompileCommands.h"
12 #include "Config.h"
13 #include "TestFS.h"
14 #include "support/Path.h"
15 #include "support/ThreadsafeFS.h"
16 #include "clang/Tooling/CompilationDatabase.h"
17 #include "llvm/ADT/Optional.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/Support/FormatVariadic.h"
22 #include "llvm/Support/Path.h"
23 #include "gmock/gmock.h"
24 #include "gtest/gtest.h"
25 #include <chrono>
26 #include <fstream>
27 #include <string>
28 
29 namespace clang {
30 namespace clangd {
31 namespace {
32 using ::testing::AllOf;
33 using ::testing::Contains;
34 using ::testing::ElementsAre;
35 using ::testing::EndsWith;
36 using ::testing::HasSubstr;
37 using ::testing::IsEmpty;
38 using ::testing::Not;
39 using ::testing::UnorderedElementsAre;
40 
TEST(GlobalCompilationDatabaseTest,FallbackCommand)41 TEST(GlobalCompilationDatabaseTest, FallbackCommand) {
42   MockFS TFS;
43   DirectoryBasedGlobalCompilationDatabase DB(TFS);
44   auto Cmd = DB.getFallbackCommand(testPath("foo/bar.cc"));
45   EXPECT_EQ(Cmd.Directory, testPath("foo"));
46   EXPECT_THAT(Cmd.CommandLine, ElementsAre("clang", testPath("foo/bar.cc")));
47   EXPECT_EQ(Cmd.Output, "");
48 
49   // .h files have unknown language, so they are parsed liberally as obj-c++.
50   Cmd = DB.getFallbackCommand(testPath("foo/bar.h"));
51   EXPECT_THAT(Cmd.CommandLine, ElementsAre("clang", "-xobjective-c++-header",
52                                            testPath("foo/bar.h")));
53   Cmd = DB.getFallbackCommand(testPath("foo/bar"));
54   EXPECT_THAT(Cmd.CommandLine, ElementsAre("clang", "-xobjective-c++-header",
55                                            testPath("foo/bar")));
56 }
57 
cmd(llvm::StringRef File,llvm::StringRef Arg)58 static tooling::CompileCommand cmd(llvm::StringRef File, llvm::StringRef Arg) {
59   return tooling::CompileCommand(
60       testRoot(), File, {"clang", std::string(Arg), std::string(File)}, "");
61 }
62 
63 class OverlayCDBTest : public ::testing::Test {
64   class BaseCDB : public GlobalCompilationDatabase {
65   public:
66     llvm::Optional<tooling::CompileCommand>
getCompileCommand(llvm::StringRef File) const67     getCompileCommand(llvm::StringRef File) const override {
68       if (File == testPath("foo.cc"))
69         return cmd(File, "-DA=1");
70       return None;
71     }
72 
73     tooling::CompileCommand
getFallbackCommand(llvm::StringRef File) const74     getFallbackCommand(llvm::StringRef File) const override {
75       return cmd(File, "-DA=2");
76     }
77 
getProjectInfo(PathRef File) const78     llvm::Optional<ProjectInfo> getProjectInfo(PathRef File) const override {
79       return ProjectInfo{testRoot()};
80     }
81   };
82 
83 protected:
OverlayCDBTest()84   OverlayCDBTest() : Base(std::make_unique<BaseCDB>()) {}
85   std::unique_ptr<GlobalCompilationDatabase> Base;
86 };
87 
TEST_F(OverlayCDBTest,GetCompileCommand)88 TEST_F(OverlayCDBTest, GetCompileCommand) {
89   OverlayCDB CDB(Base.get());
90   EXPECT_THAT(CDB.getCompileCommand(testPath("foo.cc"))->CommandLine,
91               AllOf(Contains(testPath("foo.cc")), Contains("-DA=1")));
92   EXPECT_EQ(CDB.getCompileCommand(testPath("missing.cc")), llvm::None);
93 
94   auto Override = cmd(testPath("foo.cc"), "-DA=3");
95   CDB.setCompileCommand(testPath("foo.cc"), Override);
96   EXPECT_THAT(CDB.getCompileCommand(testPath("foo.cc"))->CommandLine,
97               Contains("-DA=3"));
98   EXPECT_EQ(CDB.getCompileCommand(testPath("missing.cc")), llvm::None);
99   CDB.setCompileCommand(testPath("missing.cc"), Override);
100   EXPECT_THAT(CDB.getCompileCommand(testPath("missing.cc"))->CommandLine,
101               Contains("-DA=3"));
102 }
103 
TEST_F(OverlayCDBTest,GetFallbackCommand)104 TEST_F(OverlayCDBTest, GetFallbackCommand) {
105   OverlayCDB CDB(Base.get(), {"-DA=4"});
106   EXPECT_THAT(CDB.getFallbackCommand(testPath("bar.cc")).CommandLine,
107               ElementsAre("clang", "-DA=2", testPath("bar.cc"), "-DA=4"));
108 }
109 
TEST_F(OverlayCDBTest,NoBase)110 TEST_F(OverlayCDBTest, NoBase) {
111   OverlayCDB CDB(nullptr, {"-DA=6"});
112   EXPECT_EQ(CDB.getCompileCommand(testPath("bar.cc")), None);
113   auto Override = cmd(testPath("bar.cc"), "-DA=5");
114   CDB.setCompileCommand(testPath("bar.cc"), Override);
115   EXPECT_THAT(CDB.getCompileCommand(testPath("bar.cc"))->CommandLine,
116               Contains("-DA=5"));
117 
118   EXPECT_THAT(CDB.getFallbackCommand(testPath("foo.cc")).CommandLine,
119               ElementsAre("clang", testPath("foo.cc"), "-DA=6"));
120 }
121 
TEST_F(OverlayCDBTest,Watch)122 TEST_F(OverlayCDBTest, Watch) {
123   OverlayCDB Inner(nullptr);
124   OverlayCDB Outer(&Inner);
125 
126   std::vector<std::vector<std::string>> Changes;
127   auto Sub = Outer.watch([&](const std::vector<std::string> &ChangedFiles) {
128     Changes.push_back(ChangedFiles);
129   });
130 
131   Inner.setCompileCommand("A.cpp", tooling::CompileCommand());
132   Outer.setCompileCommand("B.cpp", tooling::CompileCommand());
133   Inner.setCompileCommand("A.cpp", llvm::None);
134   Outer.setCompileCommand("C.cpp", llvm::None);
135   EXPECT_THAT(Changes, ElementsAre(ElementsAre("A.cpp"), ElementsAre("B.cpp"),
136                                    ElementsAre("A.cpp"), ElementsAre("C.cpp")));
137 }
138 
TEST_F(OverlayCDBTest,Adjustments)139 TEST_F(OverlayCDBTest, Adjustments) {
140   OverlayCDB CDB(Base.get(), {"-DFallback"},
141                  [](const std::vector<std::string> &Cmd, llvm::StringRef File) {
142                    auto Ret = Cmd;
143                    Ret.push_back(
144                        ("-DAdjust_" + llvm::sys::path::filename(File)).str());
145                    return Ret;
146                  });
147   // Command from underlying gets adjusted.
148   auto Cmd = *CDB.getCompileCommand(testPath("foo.cc"));
149   EXPECT_THAT(Cmd.CommandLine, ElementsAre("clang", "-DA=1", testPath("foo.cc"),
150                                            "-DAdjust_foo.cc"));
151 
152   // Command from overlay gets adjusted.
153   tooling::CompileCommand BarCommand;
154   BarCommand.Filename = testPath("bar.cc");
155   BarCommand.CommandLine = {"clang++", "-DB=1", testPath("bar.cc")};
156   CDB.setCompileCommand(testPath("bar.cc"), BarCommand);
157   Cmd = *CDB.getCompileCommand(testPath("bar.cc"));
158   EXPECT_THAT(
159       Cmd.CommandLine,
160       ElementsAre("clang++", "-DB=1", testPath("bar.cc"), "-DAdjust_bar.cc"));
161 
162   // Fallback gets adjusted.
163   Cmd = CDB.getFallbackCommand("baz.cc");
164   EXPECT_THAT(Cmd.CommandLine, ElementsAre("clang", "-DA=2", "baz.cc",
165                                            "-DFallback", "-DAdjust_baz.cc"));
166 }
167 
TEST(GlobalCompilationDatabaseTest,DiscoveryWithNestedCDBs)168 TEST(GlobalCompilationDatabaseTest, DiscoveryWithNestedCDBs) {
169   const char *const CDBOuter =
170       R"cdb(
171       [
172         {
173           "file": "a.cc",
174           "command": "",
175           "directory": "{0}",
176         },
177         {
178           "file": "build/gen.cc",
179           "command": "",
180           "directory": "{0}",
181         },
182         {
183           "file": "build/gen2.cc",
184           "command": "",
185           "directory": "{0}",
186         }
187       ]
188       )cdb";
189   const char *const CDBInner =
190       R"cdb(
191       [
192         {
193           "file": "gen.cc",
194           "command": "",
195           "directory": "{0}/build",
196         }
197       ]
198       )cdb";
199   MockFS FS;
200   FS.Files[testPath("compile_commands.json")] =
201       llvm::formatv(CDBOuter, llvm::sys::path::convert_to_slash(testRoot()));
202   FS.Files[testPath("build/compile_commands.json")] =
203       llvm::formatv(CDBInner, llvm::sys::path::convert_to_slash(testRoot()));
204   FS.Files[testPath("foo/compile_flags.txt")] = "-DFOO";
205 
206   // Note that gen2.cc goes missing with our following model, not sure this
207   // happens in practice though.
208   {
209     SCOPED_TRACE("Default ancestor scanning");
210     DirectoryBasedGlobalCompilationDatabase DB(FS);
211     std::vector<std::string> DiscoveredFiles;
212     auto Sub =
213         DB.watch([&DiscoveredFiles](const std::vector<std::string> Changes) {
214           DiscoveredFiles = Changes;
215         });
216 
217     DB.getCompileCommand(testPath("build/../a.cc"));
218     ASSERT_TRUE(DB.blockUntilIdle(timeoutSeconds(10)));
219     EXPECT_THAT(DiscoveredFiles, UnorderedElementsAre(AllOf(
220                                      EndsWith("a.cc"), Not(HasSubstr("..")))));
221     DiscoveredFiles.clear();
222 
223     DB.getCompileCommand(testPath("build/gen.cc"));
224     ASSERT_TRUE(DB.blockUntilIdle(timeoutSeconds(10)));
225     EXPECT_THAT(DiscoveredFiles, UnorderedElementsAre(EndsWith("gen.cc")));
226   }
227 
228   {
229     SCOPED_TRACE("With config");
230     DirectoryBasedGlobalCompilationDatabase::Options Opts(FS);
231     Opts.ContextProvider = [&](llvm::StringRef Path) {
232       Config Cfg;
233       if (Path.endswith("a.cc")) {
234         // a.cc uses another directory's CDB, so it won't be discovered.
235         Cfg.CompileFlags.CDBSearch.Policy = Config::CDBSearchSpec::FixedDir;
236         Cfg.CompileFlags.CDBSearch.FixedCDBPath = testPath("foo");
237       } else if (Path.endswith("gen.cc")) {
238         // gen.cc has CDB search disabled, so it won't be discovered.
239         Cfg.CompileFlags.CDBSearch.Policy = Config::CDBSearchSpec::NoCDBSearch;
240       } else if (Path.endswith("gen2.cc")) {
241         // gen2.cc explicitly lists this directory, so it will be discovered.
242         Cfg.CompileFlags.CDBSearch.Policy = Config::CDBSearchSpec::FixedDir;
243         Cfg.CompileFlags.CDBSearch.FixedCDBPath = testRoot();
244       }
245       return Context::current().derive(Config::Key, std::move(Cfg));
246     };
247     DirectoryBasedGlobalCompilationDatabase DB(Opts);
248     std::vector<std::string> DiscoveredFiles;
249     auto Sub =
250         DB.watch([&DiscoveredFiles](const std::vector<std::string> Changes) {
251           DiscoveredFiles = Changes;
252         });
253 
254     // Does not use the root CDB, so no broadcast.
255     auto Cmd = DB.getCompileCommand(testPath("build/../a.cc"));
256     ASSERT_TRUE(Cmd);
257     EXPECT_THAT(Cmd->CommandLine, Contains("-DFOO")) << "a.cc uses foo/ CDB";
258     ASSERT_TRUE(DB.blockUntilIdle(timeoutSeconds(10)));
259     EXPECT_THAT(DiscoveredFiles, IsEmpty()) << "Root CDB not discovered yet";
260 
261     // No special config for b.cc, so we trigger broadcast of the root CDB.
262     DB.getCompileCommand(testPath("b.cc"));
263     ASSERT_TRUE(DB.blockUntilIdle(timeoutSeconds(10)));
264     EXPECT_THAT(DiscoveredFiles, ElementsAre(testPath("build/gen2.cc")));
265     DiscoveredFiles.clear();
266 
267     // No CDB search so no discovery/broadcast triggered for build/ CDB.
268     DB.getCompileCommand(testPath("build/gen.cc"));
269     ASSERT_TRUE(DB.blockUntilIdle(timeoutSeconds(10)));
270     EXPECT_THAT(DiscoveredFiles, IsEmpty());
271   }
272 
273   {
274     SCOPED_TRACE("With custom compile commands dir");
275     DirectoryBasedGlobalCompilationDatabase::Options Opts(FS);
276     Opts.CompileCommandsDir = testRoot();
277     DirectoryBasedGlobalCompilationDatabase DB(Opts);
278     std::vector<std::string> DiscoveredFiles;
279     auto Sub =
280         DB.watch([&DiscoveredFiles](const std::vector<std::string> Changes) {
281           DiscoveredFiles = Changes;
282         });
283 
284     DB.getCompileCommand(testPath("a.cc"));
285     ASSERT_TRUE(DB.blockUntilIdle(timeoutSeconds(10)));
286     EXPECT_THAT(DiscoveredFiles,
287                 UnorderedElementsAre(EndsWith("a.cc"), EndsWith("gen.cc"),
288                                      EndsWith("gen2.cc")));
289     DiscoveredFiles.clear();
290 
291     DB.getCompileCommand(testPath("build/gen.cc"));
292     ASSERT_TRUE(DB.blockUntilIdle(timeoutSeconds(10)));
293     EXPECT_THAT(DiscoveredFiles, IsEmpty());
294   }
295 }
296 
TEST(GlobalCompilationDatabaseTest,BuildDir)297 TEST(GlobalCompilationDatabaseTest, BuildDir) {
298   MockFS FS;
299   auto Command = [&](llvm::StringRef Relative) {
300     DirectoryBasedGlobalCompilationDatabase::Options Opts(FS);
301     return DirectoryBasedGlobalCompilationDatabase(Opts)
302         .getCompileCommand(testPath(Relative))
303         .value_or(tooling::CompileCommand())
304         .CommandLine;
305   };
306   EXPECT_THAT(Command("x/foo.cc"), IsEmpty());
307   const char *const CDB =
308       R"cdb(
309       [
310         {
311           "file": "{0}/x/foo.cc",
312           "command": "clang -DXYZZY {0}/x/foo.cc",
313           "directory": "{0}",
314         },
315         {
316           "file": "{0}/bar.cc",
317           "command": "clang -DXYZZY {0}/bar.cc",
318           "directory": "{0}",
319         }
320       ]
321       )cdb";
322   FS.Files[testPath("x/build/compile_commands.json")] =
323       llvm::formatv(CDB, llvm::sys::path::convert_to_slash(testRoot()));
324   EXPECT_THAT(Command("x/foo.cc"), Contains("-DXYZZY"));
325   EXPECT_THAT(Command("bar.cc"), IsEmpty())
326       << "x/build/compile_flags.json only applicable to x/";
327 }
328 
TEST(GlobalCompilationDatabaseTest,CompileFlagsDirectory)329 TEST(GlobalCompilationDatabaseTest, CompileFlagsDirectory) {
330   MockFS FS;
331   FS.Files[testPath("x/compile_flags.txt")] = "-DFOO";
332   DirectoryBasedGlobalCompilationDatabase CDB(FS);
333   auto Commands = CDB.getCompileCommand(testPath("x/y.cpp"));
334   ASSERT_TRUE(Commands.has_value());
335   EXPECT_THAT(Commands.value().CommandLine, Contains("-DFOO"));
336   // Make sure we pick the right working directory.
337   EXPECT_EQ(testPath("x"), Commands.value().Directory);
338 }
339 
340 MATCHER_P(hasArg, Flag, "") {
341   if (!arg) {
342     *result_listener << "command is null";
343     return false;
344   }
345   if (!llvm::is_contained(arg->CommandLine, Flag)) {
346     *result_listener << "flags are " << printArgv(arg->CommandLine);
347     return false;
348   }
349   return true;
350 }
351 
TEST(GlobalCompilationDatabaseTest,Config)352 TEST(GlobalCompilationDatabaseTest, Config) {
353   MockFS FS;
354   FS.Files[testPath("x/compile_flags.txt")] = "-DX";
355   FS.Files[testPath("x/y/z/compile_flags.txt")] = "-DZ";
356 
357   Config::CDBSearchSpec Spec;
358   DirectoryBasedGlobalCompilationDatabase::Options Opts(FS);
359   Opts.ContextProvider = [&](llvm::StringRef Path) {
360     Config C;
361     C.CompileFlags.CDBSearch = Spec;
362     return Context::current().derive(Config::Key, std::move(C));
363   };
364   DirectoryBasedGlobalCompilationDatabase CDB(Opts);
365 
366   // Default ancestor behavior.
367   EXPECT_FALSE(CDB.getCompileCommand(testPath("foo.cc")));
368   EXPECT_THAT(CDB.getCompileCommand(testPath("x/foo.cc")), hasArg("-DX"));
369   EXPECT_THAT(CDB.getCompileCommand(testPath("x/y/foo.cc")), hasArg("-DX"));
370   EXPECT_THAT(CDB.getCompileCommand(testPath("x/y/z/foo.cc")), hasArg("-DZ"));
371 
372   Spec.Policy = Config::CDBSearchSpec::NoCDBSearch;
373   EXPECT_FALSE(CDB.getCompileCommand(testPath("foo.cc")));
374   EXPECT_FALSE(CDB.getCompileCommand(testPath("x/foo.cc")));
375   EXPECT_FALSE(CDB.getCompileCommand(testPath("x/y/foo.cc")));
376   EXPECT_FALSE(CDB.getCompileCommand(testPath("x/y/z/foo.cc")));
377 
378   Spec.Policy = Config::CDBSearchSpec::FixedDir;
379   Spec.FixedCDBPath = testPath("w"); // doesn't exist
380   EXPECT_FALSE(CDB.getCompileCommand(testPath("foo.cc")));
381   EXPECT_FALSE(CDB.getCompileCommand(testPath("x/foo.cc")));
382   EXPECT_FALSE(CDB.getCompileCommand(testPath("x/y/foo.cc")));
383   EXPECT_FALSE(CDB.getCompileCommand(testPath("x/y/z/foo.cc")));
384 
385   Spec.FixedCDBPath = testPath("x/y/z");
386   EXPECT_THAT(CDB.getCompileCommand(testPath("foo.cc")), hasArg("-DZ"));
387   EXPECT_THAT(CDB.getCompileCommand(testPath("x/foo.cc")), hasArg("-DZ"));
388   EXPECT_THAT(CDB.getCompileCommand(testPath("x/y/foo.cc")), hasArg("-DZ"));
389   EXPECT_THAT(CDB.getCompileCommand(testPath("x/y/z/foo.cc")), hasArg("-DZ"));
390 }
391 
TEST(GlobalCompilationDatabaseTest,NonCanonicalFilenames)392 TEST(GlobalCompilationDatabaseTest, NonCanonicalFilenames) {
393   OverlayCDB DB(nullptr);
394   std::vector<std::string> DiscoveredFiles;
395   auto Sub =
396       DB.watch([&DiscoveredFiles](const std::vector<std::string> Changes) {
397         DiscoveredFiles = Changes;
398       });
399 
400   llvm::SmallString<128> Root(testRoot());
401   llvm::sys::path::append(Root, "build", "..", "a.cc");
402   DB.setCompileCommand(Root.str(), tooling::CompileCommand());
403   EXPECT_THAT(DiscoveredFiles, UnorderedElementsAre(testPath("a.cc")));
404   DiscoveredFiles.clear();
405 
406   llvm::SmallString<128> File(testRoot());
407   llvm::sys::path::append(File, "blabla", "..", "a.cc");
408 
409   EXPECT_TRUE(DB.getCompileCommand(File));
410   EXPECT_FALSE(DB.getProjectInfo(File));
411 }
412 
TEST_F(OverlayCDBTest,GetProjectInfo)413 TEST_F(OverlayCDBTest, GetProjectInfo) {
414   OverlayCDB DB(Base.get());
415   Path File = testPath("foo.cc");
416   Path Header = testPath("foo.h");
417 
418   EXPECT_EQ(DB.getProjectInfo(File)->SourceRoot, testRoot());
419   EXPECT_EQ(DB.getProjectInfo(Header)->SourceRoot, testRoot());
420 
421   // Shouldn't change after an override.
422   DB.setCompileCommand(File, tooling::CompileCommand());
423   EXPECT_EQ(DB.getProjectInfo(File)->SourceRoot, testRoot());
424   EXPECT_EQ(DB.getProjectInfo(Header)->SourceRoot, testRoot());
425 }
426 } // namespace
427 
428 // Friend test has access to internals.
429 class DirectoryBasedGlobalCompilationDatabaseCacheTest
430     : public ::testing::Test {
431 protected:
432   std::shared_ptr<const tooling::CompilationDatabase>
lookupCDB(const DirectoryBasedGlobalCompilationDatabase & GDB,llvm::StringRef Path,std::chrono::steady_clock::time_point FreshTime)433   lookupCDB(const DirectoryBasedGlobalCompilationDatabase &GDB,
434             llvm::StringRef Path,
435             std::chrono::steady_clock::time_point FreshTime) {
436     DirectoryBasedGlobalCompilationDatabase::CDBLookupRequest Req;
437     Req.FileName = Path;
438     Req.FreshTime = Req.FreshTimeMissing = FreshTime;
439     if (auto Result = GDB.lookupCDB(Req))
440       return std::move(Result->CDB);
441     return nullptr;
442   }
443 };
444 
445 // Matches non-null CDBs which include the specified flag.
446 MATCHER_P2(hasFlag, Flag, Path, "") {
447   if (arg == nullptr)
448     return false;
449   auto Cmds = arg->getCompileCommands(Path);
450   if (Cmds.empty()) {
451     *result_listener << "yields no commands";
452     return false;
453   }
454   if (!llvm::is_contained(Cmds.front().CommandLine, Flag)) {
455     *result_listener << "flags are: " << printArgv(Cmds.front().CommandLine);
456     return false;
457   }
458   return true;
459 }
460 
hasFlag(llvm::StringRef Flag)461 auto hasFlag(llvm::StringRef Flag) {
462   return hasFlag(Flag, "mock_file_name.cc");
463 }
464 
TEST_F(DirectoryBasedGlobalCompilationDatabaseCacheTest,Cacheable)465 TEST_F(DirectoryBasedGlobalCompilationDatabaseCacheTest, Cacheable) {
466   MockFS FS;
467   auto Stale = std::chrono::steady_clock::now() - std::chrono::minutes(1);
468   auto Fresh = std::chrono::steady_clock::now() + std::chrono::hours(24);
469 
470   DirectoryBasedGlobalCompilationDatabase GDB(FS);
471   FS.Files["compile_flags.txt"] = "-DROOT";
472   auto Root = lookupCDB(GDB, testPath("foo/test.cc"), Stale);
473   EXPECT_THAT(Root, hasFlag("-DROOT"));
474 
475   // Add a compilation database to a subdirectory - CDB loaded.
476   FS.Files["foo/compile_flags.txt"] = "-DFOO";
477   EXPECT_EQ(Root, lookupCDB(GDB, testPath("foo/test.cc"), Stale))
478       << "cache still valid";
479   auto Foo = lookupCDB(GDB, testPath("foo/test.cc"), Fresh);
480   EXPECT_THAT(Foo, hasFlag("-DFOO")) << "new cdb loaded";
481   EXPECT_EQ(Foo, lookupCDB(GDB, testPath("foo/test.cc"), Stale))
482       << "new cdb in cache";
483 
484   // Mtime changed, but no content change - CDB not reloaded.
485   ++FS.Timestamps["foo/compile_flags.txt"];
486   auto FooAgain = lookupCDB(GDB, testPath("foo/test.cc"), Fresh);
487   EXPECT_EQ(Foo, FooAgain) << "Same content, read but not reloaded";
488   // Content changed, but not size or mtime - CDB not reloaded.
489   FS.Files["foo/compile_flags.txt"] = "-DBAR";
490   auto FooAgain2 = lookupCDB(GDB, testPath("foo/test.cc"), Fresh);
491   EXPECT_EQ(Foo, FooAgain2) << "Same filesize, change not detected";
492   // Mtime change forces a re-read, and we notice the different content.
493   ++FS.Timestamps["foo/compile_flags.txt"];
494   auto Bar = lookupCDB(GDB, testPath("foo/test.cc"), Fresh);
495   EXPECT_THAT(Bar, hasFlag("-DBAR")) << "refreshed with mtime change";
496 
497   // Size and content both change - CDB reloaded.
498   FS.Files["foo/compile_flags.txt"] = "-DFOOBAR";
499   EXPECT_EQ(Bar, lookupCDB(GDB, testPath("foo/test.cc"), Stale))
500       << "cache still valid";
501   auto FooBar = lookupCDB(GDB, testPath("foo/test.cc"), Fresh);
502   EXPECT_THAT(FooBar, hasFlag("-DFOOBAR")) << "cdb reloaded";
503 
504   // compile_commands.json takes precedence over compile_flags.txt.
505   FS.Files["foo/compile_commands.json"] =
506       llvm::formatv(R"json([{
507     "file": "{0}/foo/mock_file.cc",
508     "command": "clang -DBAZ mock_file.cc",
509     "directory": "{0}/foo",
510   }])json",
511                     llvm::sys::path::convert_to_slash(testRoot()));
512   EXPECT_EQ(FooBar, lookupCDB(GDB, testPath("foo/test.cc"), Stale))
513       << "cache still valid";
514   auto Baz = lookupCDB(GDB, testPath("foo/test.cc"), Fresh);
515   EXPECT_THAT(Baz, hasFlag("-DBAZ", testPath("foo/mock_file.cc")))
516       << "compile_commands overrides compile_flags";
517 
518   // Removing compile_commands.json reveals compile_flags.txt again.
519   // However this *does* cause a CDB reload (we cache only one CDB per dir).
520   FS.Files.erase("foo/compile_commands.json");
521   auto FoobarAgain = lookupCDB(GDB, testPath("foo/test.cc"), Fresh);
522   EXPECT_THAT(FoobarAgain, hasFlag("-DFOOBAR")) << "reloaded compile_flags";
523   EXPECT_NE(FoobarAgain, FooBar) << "CDB discarded (shadowed within directory)";
524 
525   // Removing the directory's CDB leaves the parent CDB active.
526   // The parent CDB is *not* reloaded (we cache the CDB per-directory).
527   FS.Files.erase("foo/compile_flags.txt");
528   EXPECT_EQ(Root, lookupCDB(GDB, testPath("foo/test.cc"), Fresh))
529       << "CDB retained (shadowed by another directory)";
530 }
531 
532 } // namespace clangd
533 } // namespace clang
534