[clangd] Fix diagnostic location for macro expansions

[kadircet]

Summary

Diagnostic locations were broken when it was result of a macro
expansion. This patch fixes it by using expansion location instead of location
inside macro body.

Fixes https://github.com/clangd/clangd/issues/201.

[merge_guards_bot]

Build result: pass - 60059 tests passed, 0 failed and 729 were skipped.
Log files: console-log.txt, CMakeCache.txt

[hokein]

clang-tools-extra/clangd/Diagnostics.cpp

121

should we use getExpansionLoc? getFileLoc returns a spelling location if it comes from a macro argument, but I think it doesn't matter.

clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp

944

this doesn't belong to IgnoreDiags any more, I think, should be DiagsInHeaders, the same to the newly-added test.

1012

could you add one more test case where foo is spelled at macro argument? I believe it was broken as well before this patch.

#define X(arg) arg
X(foo);

[kadircet]

clang-tools-extra/clangd/Diagnostics.cpp

121

right

clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp

944

ah thanks!

[kadircet]

• Address comments

[merge_guards_bot]

Build result: pass - 60220 tests passed, 0 failed and 732 were skipped.

Log files: console-log.txt, CMakeCache.txt

[hokein]

clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp

995

I'd move this to the end of the file, so that all DiagsInHeaders are grouped together.

[kadircet]

• Group similar tests together

clang-tools-extra/clangd/Diagnostics.cpp

 
 // Returns whether the \p D is modified.
 bool adjustDiagFromHeader(Diag &D, const clang::Diagnostic &Info,
                           const LangOptions &LangOpts) {
   // We only report diagnostics with at least error severity from headers.
   if (D.Severity < DiagnosticsEngine::Level::Error)
     return false;
 
-  const SourceLocation &DiagLoc = Info.getLocation();
   const SourceManager &SM = Info.getSourceManager();
+  const SourceLocation &DiagLoc = SM.getExpansionLoc(Info.getLocation());
   SourceLocation IncludeInMainFile;
   auto GetIncludeLoc = [&SM](SourceLocation SLoc) {
     return SM.getIncludeLoc(SM.getFileID(SLoc));
   };
   for (auto IncludeLocation = GetIncludeLoc(DiagLoc); IncludeLocation.isValid();
        IncludeLocation = GetIncludeLoc(IncludeLocation)) {
     if (clangd::isInsideMainFile(IncludeLocation, SM)) {
       IncludeInMainFile = IncludeLocation;

clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp

TEST(DiagsInHeaders, OnlyErrorOrFatal) {
   TU.AdditionalFiles = {{"a.h", Header.code()}};
   EXPECT_THAT(TU.build().getDiagnostics(),
               UnorderedElementsAre(AllOf(
                   Diag(Main.range(), "in included file: C++ requires "
                                      "a type specifier for all declarations"),
                   WithNote(Diag(Header.range(), "error occurred here")))));
 }
 
-TEST(IgnoreDiags, FromNonWrittenSources) {
+TEST(DiagsInHeaders, FromNonWrittenSources) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     void foo() {})cpp");
   Annotations Header(R"cpp(
     int x = 5/0;
     int b = [[FOO]];)cpp");
   TestTU TU = TestTU::withCode(Main.code());
   TU.AdditionalFiles = {{"a.h", Header.code()}};
   TU.ExtraArgs = {"-DFOO=NOOO"};
-  EXPECT_THAT(TU.build().getDiagnostics(), UnorderedElementsAre());
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(AllOf(
+                  Diag(Main.range(),
+                       "in included file: use of undeclared identifier 'NOOO'"),
+                  WithNote(Diag(Header.range(), "error occurred here")))));
+}
+
+TEST(DiagsInHeaders, ErrorFromMacroExpansion) {
+  Annotations Main(R"cpp(
+  void bar() {
+    int fo;
+    #include [["a.h"]]
+  })cpp");
+  Annotations Header(R"cpp(
+  #define X foo
+  X;)cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", Header.code()}};
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(
+                  Diag(Main.range(), "in included file: use of undeclared "
+                                     "identifier 'foo'; did you mean 'fo'?")));
+}
+
+TEST(DiagsInHeaders, ErrorFromMacroArgument) {
+  Annotations Main(R"cpp(
+  void bar() {
+    int fo;
+    #include [["a.h"]]
+  })cpp");
+  Annotations Header(R"cpp(
+  #define X(arg) arg
+  X(foo);)cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", Header.code()}};
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(
+                  Diag(Main.range(), "in included file: use of undeclared "
+                                     "identifier 'foo'; did you mean 'fo'?")));
 }
 
 TEST(IgnoreDiags, FromNonWrittenInclude) {
-  TestTU TU = TestTU::withCode("");
+  TestTU TU;
   TU.ExtraArgs.push_back("--include=a.h");
   TU.AdditionalFiles = {{"a.h", "void main();"}};
   // The diagnostic "main must return int" is from the header, we don't attempt
   // to render it in the main file as there is no written location there.
   EXPECT_THAT(TU.build().getDiagnostics(), UnorderedElementsAre());
 }
 
 } // namespace
-
 } // namespace clangd
 } // namespace clang