[clangd] Fix diagnostic location for macro expansions

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.

Reviewers: hokein

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70494

2 files changed, 42 insertions, 5 deletions

diff --git a/clang-tools-extra/clangd/Diagnostics.cpp b/clang-tools-extra/clangd/Diagnostics.cpp
index c9e1ed6bc68..cd95807162b 100644
--- a/clang-tools-extra/clangd/Diagnostics.cpp
+++ b/clang-tools-extra/clangd/Diagnostics.cpp
@@ -117,8 +117,8 @@ bool adjustDiagFromHeader(Diag &D, const clang::Diagnostic &Info,
   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));
diff --git a/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp b/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
index 374dae073e0..fe7a8898c5d 100644
--- a/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
@@ -941,7 +941,7 @@ TEST(DiagsInHeaders, OnlyErrorOrFatal) {
                   WithNote(Diag(Header.range(), "error occurred here")))));
 }
 
-TEST(IgnoreDiags, FromNonWrittenSources) {
+TEST(DiagsInHeaders, FromNonWrittenSources) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     void foo() {})cpp");
@@ -951,11 +951,49 @@ TEST(IgnoreDiags, FromNonWrittenSources) {
   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
@@ -964,6 +1002,5 @@ TEST(IgnoreDiags, FromNonWrittenInclude) {
 }
 
 } // namespace
-
 } // namespace clangd
 } // namespace clang