[clangd] Surface diagnostics from headers inside main file

[ilya-biryukov]

I'll look more closely into the details, but just a high-level question now: why would we want to make this optional and not simply surface these extra diagnostics?

[kadircet]

In D59302#1431045, @ilya-biryukov wrote:

I'll look more closely into the details, but just a high-level question now: why would we want to make this optional and not simply surface these extra diagnostics?

The optional part is rather limiting number of diagnostics that is going to be surfaced. So if you have thousands of errors inside preamble only first 100 of them will appear inside main file by default.
But looking at it again, currently there is no way for user to say "do not limit number of diagnostics" :D They can only change this limit to different values.

[kadircet]

• Only surface diagnostics with level fatal or error

[ilya-biryukov]

In D59302#1431274, @kadircet wrote:

The optional part is rather limiting number of diagnostics that is going to be surfaced. So if you have thousands of errors inside preamble only first 100 of them will appear inside main file by default.
But looking at it again, currently there is no way for user to say "do not limit number of diagnostics" :D They can only change this limit to different values.

Let's pick a number and hard-code it. We'll get consistent behavior in all clients of clangd, I can hardly think of any existing client that would want to surface everything to the user.
FWIW, 100 seem too much to my taste, since we're only showing errors. Would 10 be a better limit?

[ilya-biryukov]

clangd/ClangdUnit.cpp

256 ↗

(On Diff #191265)

We should find a way to point into an exact include directive (source locations have this information).

406 ↗

(On Diff #191265)

Could we limit per-include-directive instead?
The limit to avoid creating too verbose error messages, rather than reporting too many messages, right?

438 ↗

(On Diff #191265)

We should provide the include stack, similar to how compiler does it.
Otherwise it would be really hard to figure out the exact problem the diagnostic is pointing at.

[kadircet]

• Show include stack in diagnostic message
• Point to exact include location

[kadircet]

• Limit per include directive
• Use hardcoded value for limit

[kadircet]

• Make limit a hardcoded value rather then a command line argument
• Limit diags per include directive

[ilya-biryukov]

Thanks for changes. A few more comments.

clangd/ClangdUnit.cpp

259 ↗

(On Diff #191465)

Could we binary-search in a sorted vector<Inclusion> with a custom comparator instead?

411 ↗

(On Diff #191465)

The function name suggests it does not have side-effects.
Maybe handle the update and query of NumberOfDiagstAtLine outside this function instead?

clangd/Diagnostics.cpp

396 ↗

(On Diff #191465)

NIT: could we reuse the function from clang that does the same thing?

The code here is pretty simple, though, so writing it here is fine. Just wanted to make sure we considered this option and found it's easier to redo this work ourselves.

419 ↗

(On Diff #191465)

We can still drop diagnostics at some point, right?
Could we move the log statement in a different point?

clangd/Diagnostics.h

87 ↗

(On Diff #191465)

Could we avoid changing this interface?
We have enough information to fill the corresponding range and message when collecting diagnostics inside our implementation of clang's DiagnosticConsumer, there's really no point in carrying this information in this struct.

If that means intermediate structures stored in our consumer, so be it, it's a private implementation detail. Diag is a public interface, so keeping it simpler is valuable.

unittests/clangd/DiagnosticsTests.cpp

773 ↗

(On Diff #191465)

NIT: maybe use raw string literals to keep the message a one-liner?

779 ↗

(On Diff #191465)

Could we add a test for reaching the limit?
Could we mention that some diagnostics were dropped in that case? Something like:

In file included from a.h:20:1:
error: unresolved identifier 'foo'.

And 10 more diagnostics...

[kadircet]

• Address comments

clangd/Diagnostics.cpp

396 ↗

(On Diff #191465)

there is TextDiagnostic which prints the desired output expect the fact that it also prints the first line saying the header was included in main file. Therefore, I didn't make use of it since we decided that was not very useful for our use case. And it requires inheriting from DiagnosticRenderer which was requiring too much boiler plate code just to get this functionality so instead I've chosen doing it like this.

Can fallback to TextDiagnostic if you believe showing Included in mainfile.cc:x:y: at the beginning of the diagnostic won't be annoying.

unittests/clangd/DiagnosticsTests.cpp

779 ↗

(On Diff #191465)

There is already one, see LimitDiagsOutsideMainFile

[ilya-biryukov]

clangd/ClangdUnit.cpp

405 ↗

(On Diff #191831)

The name suggests we filter all diagnostics based on this helper.
Maybe add rename to something more specific?

E.g. IsErrorOrFatal or IsImporantHeaderDiagnostic...

408 ↗

(On Diff #191831)

NIT: simplify to

return D.Severity == DiagnosticsEngine::Level::Error
    || D.Severity == DiagnosticsEngine::Level::Fatal

414 ↗

(On Diff #191831)

NIT: rename to AddDiagnosticFromInclude or something similar, but more specific than the current name

425 ↗

(On Diff #191831)

Why not merge the ShouldSurfaceDiag and TryAddDiag into a single function and handle all the complexities there?
This would simplify the client code, it would be as simple as

else
 AddDiagnosticFromInclude(D)

434 ↗

(On Diff #191831)

Can we do this in StoreDiags::flushLastDiag?
All code handling the diagnostics lives there and it has all the information necessary to map to the included line.

445 ↗

(On Diff #191831)

This extra complexity does not seem to be worth it after all.
I'd suggest to remove this (at least from the first version of the file), even though I was the one who proposed it.

Still think it's valuable, but the patch is complicated enough as it is, keeping it simpler seems to be more important at this point.

clangd/Diagnostics.cpp

371 ↗

(On Diff #191831)

That's a lot of code, could we extract this into a separate function?

372 ↗

(On Diff #191831)

Why use getPresumedLoc? Making clangd sensitive to pp directives that rename file or change line numbers does not make any sense.

Could you also add tests for that?

396 ↗

(On Diff #191465)

LG, it's not too hard to reconstruct the same output.
Note that D60267 starts outputting notes in a structured way, using the RelatedInformation struct from the LSP.

We should eventually add the include stack into related information too. With that in mind, we should probably add the include stack as a new field to the struct we use for diagnostics.

[kadircet]

• Address comments

clangd/Diagnostics.cpp

372 ↗

(On Diff #191831)

It was the way DiagnosticRenderer emitted include stacks, I had just copied it over.
Changing with SourceManger::getIncludeLoc

396 ↗

(On Diff #191465)

SG, delaying serialization to LSP layer then.

[kadircet]

Ping

[ilya-biryukov]

Sorry, lost this revision. Looking now

[ilya-biryukov]

clangd/ClangdUnit.cpp

251 ↗

(On Diff #194528)

NIT: use llvm::lower_bound

252 ↗

(On Diff #194528)

NIT: lower_bound also works when you work on a different type, no need for the temporary variable.

lower_bound(MainFileIncludes…, [](const Inclusion &L, const Position &Pos) {
  return L.start.line < Pos.line;
})

(the order of lamda parameters might need to be reversed, I always forget what's the correct one)

255 ↗

(On Diff #194528)

NIT: add a sanity check that the include was actually there: assert(Res->R == Pos)

clangd/Diagnostics.cpp

55 ↗

(On Diff #194528)

reduce nesting by inverting the condition:

if (IncludeStack.empty())
  return;
// rest of the code

205 ↗

(On Diff #194528)

Could we get the message first and the include stack later?
The first line is often showed in various lists and having In file included from there is not very helpful.

463 ↗

(On Diff #194528)

Could you inline ShouldAddDiag into its single callsite?

clangd/Diagnostics.h

87 ↗

(On Diff #194528)

Could you store pair</*Filename*/string, Position> instead?
Would make it simpler to adapt D60267 to this change.

131 ↗

(On Diff #194528)

NIT: use tripple slash comments

132 ↗

(On Diff #194528)

NIT: the name makes me believe this does a different thing. Maybe mention "include" in the name to make it less confusing?
Something like DiagsInsideIncludes would work.

Another NIT: we don't need a map anymore: DenseSet<int> should be enough

unittests/clangd/DiagnosticsTests.cpp

54 ↗

(On Diff #194528)

NIT: maybe simplify to std::equal(IncludeStack.begin(), IncludeStack.end(), arg.IncludeStack.begin())

620 ↗

(On Diff #194528)

We were discussing adding the extra files to TestTU instead.
Any reason this did not work out?

[kadircet]

• Address comments

unittests/clangd/DiagnosticsTests.cpp

620 ↗

(On Diff #194528)

Yes, my LRU cache evicted the discussion :D

[ilya-biryukov]

clangd/Diagnostics.cpp

78 ↗

(On Diff #195375)

Could we avoid introducing a function that breaks the invariant of a type?
Having a function to print Position differently would be a much better fit.

225 ↗

(On Diff #195375)

WDYT about changing this to a shorter form?

include stack:

./project/foo.h:312
/usr/include/vector:344

Note that it does not mention column numbers as they aren't useful and is shorter.
Since we're already not 100% aligned with clang, why not have a more concise representation?

unittests/clangd/DiagnosticsTests.cpp

739 ↗

(On Diff #195375)

So the last location in the include stack is actually the original location of an error.
This is non-obvious design. Maybe move this into a separate field?

unittests/clangd/TestTU.h

51 ↗

(On Diff #195375)

Maybe use relative paths?
This would be consistent with Filename and HeaderFilename

52 ↗

(On Diff #195375)

Why not StringMap</*Content*/std::string>?
This would be consistent with buildTestFS and disallow adding duplicates.

[kadircet]

• Address comments
• Drop include stack

[kadircet]

clangd/Diagnostics.cpp

78 ↗

(On Diff #195375)

No longer needed reverting.

225 ↗

(On Diff #195375)

As discussed offline getting rid of include stack in this version of the patch.

[ilya-biryukov]

clangd/Diagnostics.cpp

115 ↗

(On Diff #196822)

replace vector<SourceLocation> with SourceLocation now that we only need one of the locations.

unittests/clangd/DiagnosticsTests.cpp

748 ↗

(On Diff #196822)

NIT: maybe quote the name of the header for better readability: error in include 'c.h' ...?

[ilya-biryukov]

This looks nice and minimal, thanks!
Happy to LGTM this, unless @sammccall want to take another look (e.g. to account for related information patch)

[kadircet]

• Address comments

[sammccall]

Nice! Just readability/wording nits

clangd/Diagnostics.cpp

137 ↗

(On Diff #196822)

Clang tends to use a phrase ending in "here" for such notes.
Suggest "error occurred here"

137 ↗

(On Diff #196822)

message should not be capitalized (capitalization will be added later if needed)

141 ↗

(On Diff #196822)

Include is not a noun. "included file"?

141 ↗

(On Diff #196822)

"Error" is the severity, which appears elsewhere in LSP. (Other messages do not include it)

141 ↗

(On Diff #196822)

message should not be capitalized

142 ↗

(On Diff #196822)

why are we including the filename here?

it obscures the error message, and will be available via the note.

463 ↗

(On Diff #194528)

Does this improve readability over (inline) D.Severity >= DiagnosticsEngine::Error?

clangd/Diagnostics.h

141 ↗

(On Diff #196822)

nit: "containing an error" (and variable name)

IncludeLinesWithErrors might be a clearer name

[kadircet]

• Address comments

[kadircet]

• Rebase

clang-tools-extra/trunk/clangd/Diagnostics.h

 //===--- Diagnostics.h -------------------------------------------*- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_DIAGNOSTICS_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_DIAGNOSTICS_H
 
 #include "Path.h"
 #include "Protocol.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/LangOptions.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringSet.h"
 #include <cassert>
 #include <string>
 
 namespace clang {
 namespace tidy {
 class ClangTidyContext;

 
 private:
   void flushLastDiag();
 
   DiagFixer Fixer = nullptr;
   std::vector<Diag> Output;
   llvm::Optional<LangOptions> LangOpts;
   llvm::Optional<Diag> LastDiag;
+  llvm::DenseSet<int> IncludeLinesWithErrors;
 };
 
 } // namespace clangd
 } // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_DIAGNOSTICS_H

clang-tools-extra/trunk/clangd/Diagnostics.cpp

 //===--- Diagnostics.cpp -----------------------------------------*- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "Diagnostics.h"
 #include "../clang-tidy/ClangTidyDiagnosticConsumer.h"
 #include "Compiler.h"
 #include "Logger.h"
 #include "Protocol.h"
 #include "SourceCode.h"
 #include "clang/Basic/AllDiagnostics.h"
+#include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticIDs.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Lexer.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
 #include "llvm/Support/Capacity.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/ScopedPrinter.h"
+#include "llvm/Support/Signals.h"
 #include <algorithm>
 
 namespace clang {
 namespace clangd {
 namespace {
 
 const char *getDiagnosticCode(unsigned ID) {
   switch (ID) {
if (FallbackRange)
     return *FallbackRange;
   // If no suitable range is found, just use the token at the location.
   auto R = Lexer::makeFileCharRange(CharSourceRange::getTokenRange(Loc), M, L);
   if (!R.isValid()) // Fall back to location only, let the editor deal with it.
     R = CharSourceRange::getCharRange(Loc);
   return halfOpenToRange(M, R);
 }
 
+void adjustDiagFromHeader(Diag &D, const clang::Diagnostic &Info,
+                          const LangOptions &LangOpts) {
+  const SourceLocation &DiagLoc = Info.getLocation();
+  const SourceManager &SM = Info.getSourceManager();
+  SourceLocation IncludeInMainFile;
+  auto GetIncludeLoc = [&SM](SourceLocation SLoc) {
+    return SM.getIncludeLoc(SM.getFileID(SLoc));
+  };
+  for (auto IncludeLocation = GetIncludeLoc(DiagLoc); IncludeLocation.isValid();
+       IncludeLocation = GetIncludeLoc(IncludeLocation))
+    IncludeInMainFile = IncludeLocation;
+  if (IncludeInMainFile.isInvalid())
+    return;
+
+  // Update diag to point at include inside main file.
+  D.File = SM.getFileEntryForID(SM.getMainFileID())->getName().str();
+  D.Range.start = sourceLocToPosition(SM, IncludeInMainFile);
+  D.Range.end = sourceLocToPosition(
+      SM, Lexer::getLocForEndOfToken(IncludeInMainFile, 0, SM, LangOpts));
+
+  // Add a note that will point to real diagnostic.
+  const auto *FE = SM.getFileEntryForID(SM.getFileID(DiagLoc));
+  D.Notes.emplace_back();
+  Note &N = D.Notes.back();
+  N.AbsFile = FE->tryGetRealPathName();
+  N.File = FE->getName();
+  N.Message = "error occurred here";
+  N.Range = diagnosticRange(Info, LangOpts);
+
+  // Update message to mention original file.
+  D.Message = llvm::Twine("in included file: ", D.Message).str();
+}
+
 bool isInsideMainFile(const SourceLocation Loc, const SourceManager &M) {
   return Loc.isValid() && M.isWrittenInMainFile(M.getFileLoc(Loc));
 }
 
 bool isInsideMainFile(const clang::Diagnostic &D) {
   if (!D.hasSourceManager())
     return false;
 
if (Tidy != nullptr) {
         // It would be much nicer to make clang-tidy not do this.
         auto CleanMessage = [&](std::string &Msg) {
           StringRef Rest(Msg);
           if (Rest.consume_back("]") && Rest.consume_back(Diag.Name) &&
               Rest.consume_back(" ["))
             Msg.resize(Rest.size());
         };
         CleanMessage(Diag.Message);
-        for (auto& Note : Diag.Notes)
+        for (auto &Note : Diag.Notes)
           CleanMessage(Note.Message);
         continue;
       }
     }
   }
   return std::move(Output);
 }
 
void StoreDiags::HandleDiagnostic(DiagnosticsEngine::Level DiagLevel,
 
   if (!isNote(DiagLevel)) {
     // Handle the new main diagnostic.
     flushLastDiag();
 
     LastDiag = Diag();
     LastDiag->ID = Info.getID();
     FillDiagBase(*LastDiag);
+    adjustDiagFromHeader(*LastDiag, Info, *LangOpts);
 
     if (!Info.getFixItHints().empty())
       AddFix(true /* try to invent a message instead of repeating the diag */);
     if (Fixer) {
       auto ExtraFixes = Fixer(DiagLevel, Info);
       LastDiag->Fixes.insert(LastDiag->Fixes.end(), ExtraFixes.begin(),
                              ExtraFixes.end());
     }
if (!Info.getFixItHints().empty()) {
       LastDiag->Notes.push_back(std::move(N));
     }
   }
 }
 
 void StoreDiags::flushLastDiag() {
   if (!LastDiag)
     return;
-  if (mentionsMainFile(*LastDiag))
+  // Only keeps diagnostics inside main file or the first one coming from a
+  // header.
+  if (mentionsMainFile(*LastDiag) ||
+      (LastDiag->Severity >= DiagnosticsEngine::Level::Error &&
+       IncludeLinesWithErrors.insert(LastDiag->Range.start.line).second)) {
     Output.push_back(std::move(*LastDiag));
-  else
-    vlog("Dropped diagnostic outside main file: {0}: {1}", LastDiag->File,
-         LastDiag->Message);
+  } else {
+    vlog("Dropped diagnostic: {0}: {1}", LastDiag->File, LastDiag->Message);
+  }
   LastDiag.reset();
 }
 
 } // namespace clangd
 } // namespace clang

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

 //===--- DiagnosticsTests.cpp ------------------------------------*- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "Annotations.h"
 #include "ClangdUnit.h"
 #include "Diagnostics.h"
+#include "Path.h"
 #include "Protocol.h"
 #include "SourceCode.h"
-#include "TestIndex.h"
 #include "TestFS.h"
+#include "TestIndex.h"
 #include "TestTU.h"
 #include "index/MemIndex.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticSema.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <algorithm>
 
 namespace clang {
 namespace clangd {
 namespace {
 
 using testing::_;
 using testing::ElementsAre;
 using testing::Field;
MATCHER_P3(Fix, Range, Replacement, Message,
   return arg.Message == Message && arg.Edits.size() == 1 &&
          arg.Edits[0].range == Range && arg.Edits[0].newText == Replacement;
 }
 
 MATCHER_P(EqualToLSPDiag, LSPDiag,
           "LSP diagnostic " + llvm::to_string(LSPDiag)) {
   if (toJSON(arg) != toJSON(LSPDiag)) {
     *result_listener << llvm::formatv("expected:\n{0:2}\ngot\n{1:2}",
-                                      toJSON(LSPDiag), toJSON(arg)).str();
+                                      toJSON(LSPDiag), toJSON(arg))
+                            .str();
     return false;
   }
   return true;
 }
 
 MATCHER_P(DiagSource, S, "") { return arg.Source == S; }
 MATCHER_P(DiagName, N, "") { return arg.Name == N; }
 
 MATCHER_P(EqualToFix, Fix, "LSP fix " + llvm::to_string(Fix)) {
   if (arg.Message != Fix.Message)
     return false;
   if (arg.Edits.size() != Fix.Edits.size())
     return false;
   for (std::size_t I = 0; I < arg.Edits.size(); ++I) {
     if (arg.Edits[I].range != Fix.Edits[I].range ||
         arg.Edits[I].newText != Fix.Edits[I].newText)
       return false;
   }
   return true;
 }
 
-
 // Helper function to make tests shorter.
 Position pos(int line, int character) {
   Position Res;
   Res.line = line;
   Res.character = character;
   return Res;
 }
 
o]]();
     }
   )cpp");
   EXPECT_THAT(
       TestTU::withCode(Test.code()).build().getDiagnostics(),
       ElementsAre(
           // This range spans lines.
           AllOf(Diag(Test.range("typo"),
                      "use of undeclared identifier 'goo'; did you mean 'foo'?"),
-                DiagSource(Diag::Clang),
-                DiagName("undeclared_var_use_suggest"),
+                DiagSource(Diag::Clang), DiagName("undeclared_var_use_suggest"),
                 WithFix(
                     Fix(Test.range("typo"), "foo", "change 'go\\ o' to 'foo'")),
                 // This is a pretty normal range.
                 WithNote(Diag(Test.range("decl"), "'foo' declared here"))),
           // This range is zero-width and insertion. Therefore make sure we are
           // not expanding it into other tokens. Since we are not going to
           // replace those.
           AllOf(Diag(Test.range("semicolon"), "expected ';' after expression"),
TEST(DiagnosticsTest, ToLSP) {
   D.Fixes.push_back(F);
 
   // Diagnostics should turn into these:
   clangd::Diagnostic MainLSP;
   MainLSP.range = D.Range;
   MainLSP.severity = getSeverity(DiagnosticsEngine::Error);
   MainLSP.code = "enum_class_reference";
   MainLSP.source = "clang";
-  MainLSP.message = R"(Something terrible happened (fix available)
+  MainLSP.message =
+      R"(Something terrible happened (fix available)
 
 main.cpp:6:7: remark: declared somewhere in the main file
 
 ../foo/baz/header.h:10:11:
 note: declared somewhere in the header file)";
 
   clangd::Diagnostic NoteInMainLSP;
   NoteInMainLSP.range = NoteInMain.Range;
main.cpp:2:3: error: something terrible happened)";
   NoteInMainDRI.location.range = NoteInMain.Range;
   NoteInMainDRI.location.uri = MainFile;
   MainLSP.relatedInformation = {NoteInMainDRI};
   DiagnosticRelatedInformation NoteInHeaderDRI;
   NoteInHeaderDRI.message = "Declared somewhere in the header file";
   NoteInHeaderDRI.location.range = NoteInHeader.Range;
   NoteInHeaderDRI.location.uri = HeaderFile;
   MainLSP.relatedInformation = {NoteInMainDRI, NoteInHeaderDRI};
-  EXPECT_THAT(
-      LSPDiags,
-      ElementsAre(Pair(EqualToLSPDiag(MainLSP), ElementsAre(EqualToFix(F)))));
+  EXPECT_THAT(LSPDiags, ElementsAre(Pair(EqualToLSPDiag(MainLSP),
+                                         ElementsAre(EqualToFix(F)))));
 }
 
 struct SymbolWithHeader {
   std::string QName;
   std::string DeclaringFile;
   std::string IncludeHeader;
 };
 
namespace c {
 
   EXPECT_THAT(TU.build().getDiagnostics(),
               UnorderedElementsAre(AllOf(
                   Diag(Test.range(), "no type named 'X' in namespace 'a'"),
                   WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                               "Add include \"x.h\" for symbol a::X")))));
 }
 
+TEST(DiagsInHeaders, DiagInsideHeader) {
+  Annotations Main(R"cpp(
+    #include [["a.h"]]
+    void foo() {})cpp");
+  Annotations Header("[[no_type_spec]];");
+  TestTU TU = TestTU::withCode(Main.code());
+  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(DiagsInHeaders, DiagInTransitiveInclude) {
+  Annotations Main(R"cpp(
+    #include [["a.h"]]
+    void foo() {})cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", "#include \"b.h\""}, {"b.h", "no_type_spec;"}};
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(
+                  Diag(Main.range(), "in included file: C++ requires a "
+                                     "type specifier for all declarations")));
+}
+
+TEST(DiagsInHeaders, DiagInMultipleHeaders) {
+  Annotations Main(R"cpp(
+    #include $a[["a.h"]]
+    #include $b[["b.h"]]
+    void foo() {})cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", "no_type_spec;"}, {"b.h", "no_type_spec;"}};
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(
+                  Diag(Main.range("a"), "in included file: C++ requires a type "
+                                        "specifier for all declarations"),
+                  Diag(Main.range("b"), "in included file: C++ requires a type "
+                                        "specifier for all declarations")));
+}
+
+TEST(DiagsInHeaders, PreferExpansionLocation) {
+  Annotations Main(R"cpp(
+    #include [["a.h"]]
+    #include "b.h"
+    void foo() {})cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", "#include \"b.h\"\n"},
+                        {"b.h", "#ifndef X\n#define X\nno_type_spec;\n#endif"}};
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(Diag(Main.range(),
+                                        "in included file: C++ requires a type "
+                                        "specifier for all declarations")));
+}
+
+TEST(DiagsInHeaders, PreferExpansionLocationMacros) {
+  Annotations Main(R"cpp(
+    #define X
+    #include "a.h"
+    #undef X
+    #include [["b.h"]]
+    void foo() {})cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", "#include \"c.h\"\n"},
+                        {"b.h", "#include \"c.h\"\n"},
+                        {"c.h", "#ifndef X\n#define X\nno_type_spec;\n#endif"}};
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(
+                  Diag(Main.range(), "in included file: C++ requires a "
+                                     "type specifier for all declarations")));
+}
+
+TEST(DiagsInHeaders, LimitDiagsOutsideMainFile) {
+  Annotations Main(R"cpp(
+    #include [["a.h"]]
+    #include "b.h"
+    void foo() {})cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", "#include \"c.h\"\n"},
+                        {"b.h", "#include \"c.h\"\n"},
+                        {"c.h", R"cpp(
+      #ifndef X
+      #define X
+      no_type_spec_0;
+      no_type_spec_1;
+      no_type_spec_2;
+      no_type_spec_3;
+      no_type_spec_4;
+      no_type_spec_5;
+      no_type_spec_6;
+      no_type_spec_7;
+      no_type_spec_8;
+      no_type_spec_9;
+      no_type_spec_10;
+      #endif)cpp"}};
+  EXPECT_THAT(TU.build().getDiagnostics(),
+              UnorderedElementsAre(
+                  Diag(Main.range(), "in included file: C++ requires a "
+                                     "type specifier for all declarations")));
+}
+
+TEST(DiagsInHeaders, OnlyErrorOrFatal) {
+  Annotations Main(R"cpp(
+    #include [["a.h"]]
+    void foo() {})cpp");
+  Annotations Header(R"cpp(
+    [[no_type_spec]];
+    int x = 5/0;)cpp");
+  TestTU TU = TestTU::withCode(Main.code());
+  TU.AdditionalFiles = {{"a.h", Header.code()}};
+  auto diags = TU.build().getDiagnostics();
+  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")))));
+}
 } // namespace
+
 } // namespace clangd
 } // namespace clang
-

clang-tools-extra/trunk/clangd/unittests/TestTU.h

 // AST, particular symbols, etc.
 //
 //===---------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_TOOLS_EXTRA_UNITTESTS_CLANGD_TESTTU_H
 #define LLVM_CLANG_TOOLS_EXTRA_UNITTESTS_CLANGD_TESTTU_H
 
 #include "ClangdUnit.h"
+#include "Path.h"
 #include "index/Index.h"
+#include "llvm/ADT/StringMap.h"
 #include "gtest/gtest.h"
+#include <string>
+#include <utility>
+#include <vector>
 
 namespace clang {
 namespace clangd {
 
 struct TestTU {
   static TestTU withCode(llvm::StringRef Code) {
     TestTU TU;
     TU.Code = Code;
struct TestTU {
   // The code to be compiled.
   std::string Code;
   std::string Filename = "TestTU.cpp";
 
   // Define contents of a header which will be implicitly included by Code.
   std::string HeaderCode;
   std::string HeaderFilename = "TestTU.h";
 
+  // Name and contents of each file.
+  llvm::StringMap<std::string> AdditionalFiles;
+
   // Extra arguments for the compiler invocation.
   std::vector<const char *> ExtraArgs;
 
   llvm::Optional<std::string> ClangTidyChecks;
   // Index to use when building AST.
   const SymbolIndex *ExternalIndex = nullptr;
 
   // Simulate a header guard of the header (using an #import directive).

clang-tools-extra/trunk/clangd/unittests/TestTU.cpp

 
 namespace clang {
 namespace clangd {
 
 ParsedAST TestTU::build() const {
   std::string FullFilename = testPath(Filename),
               FullHeaderName = testPath(HeaderFilename),
               ImportThunk = testPath("import_thunk.h");
-  std::vector<const char *> Cmd = {"clang", FullFilename.c_str()};
   // We want to implicitly include HeaderFilename without messing up offsets.
   // -include achieves this, but sometimes we want #import (to simulate a header
   // guard without messing up offsets). In this case, use an intermediate file.
   std::string ThunkContents = "#import \"" + FullHeaderName + "\"\n";
+
+  llvm::StringMap<std::string> Files(AdditionalFiles);
+  Files[FullFilename] = Code;
+  Files[FullHeaderName] = HeaderCode;
+  Files[ImportThunk] = ThunkContents;
+
+  std::vector<const char *> Cmd = {"clang", FullFilename.c_str()};
   // FIXME: this shouldn't need to be conditional, but it breaks a
   // GoToDefinition test for some reason (getMacroArgExpandedLocation fails).
   if (!HeaderCode.empty()) {
     Cmd.push_back("-include");
     Cmd.push_back(ImplicitHeaderGuard ? ImportThunk.c_str()
                                       : FullHeaderName.c_str());
   }
   Cmd.insert(Cmd.end(), ExtraArgs.begin(), ExtraArgs.end());
   ParseInputs Inputs;
   Inputs.CompileCommand.Filename = FullFilename;
   Inputs.CompileCommand.CommandLine = {Cmd.begin(), Cmd.end()};
   Inputs.CompileCommand.Directory = testRoot();
   Inputs.Contents = Code;
-  Inputs.FS = buildTestFS({{FullFilename, Code},
-                           {FullHeaderName, HeaderCode},
-                           {ImportThunk, ThunkContents}});
+  Inputs.FS = buildTestFS(Files);
   Inputs.Opts = ParseOptions();
   Inputs.Opts.ClangTidyOpts.Checks = ClangTidyChecks;
   Inputs.Index = ExternalIndex;
   if (Inputs.Index)
     Inputs.Opts.SuggestMissingIncludes = true;
   auto CI = buildCompilerInvocation(Inputs);
   assert(CI && "Failed to build compilation invocation.");
   auto Preamble =