[clangd] Do not inlay hints pertaining to code in other files

[nridge]

Summary

Fixes https://github.com/clangd/clangd/issues/817

[sammccall]

clang-tools-extra/clangd/InlayHints.cpp

320

nit: getSourceManager().isWrittenInMainFile(FileRange->getBegin())

[kadircet]

clang-tools-extra/clangd/InlayHints.cpp

320

double nit: isInsideMainFile(Loc, SM), I presume we would like to keep hints in preamble section as well (even though it is unlikely that we'll have any)

[sammccall]

clang-tools-extra/clangd/InlayHints.cpp

320

Yeah I did think about that too :-) I don't think we have any that can trigger there, and isInsideMainFile is more expensive.
I'm fine with either version though.

[nridge]

Address review comment

clang-tools-extra/clangd/InlayHints.cpp

 //===--- InlayHints.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 "InlayHints.h"
 #include "HeuristicResolver.h"
 #include "ParsedAST.h"
 #include "support/Logger.h"
 #include "clang/AST/DeclarationName.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/SourceManager.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace clang {
 namespace clangd {
 
 class InlayHintVisitor : public RecursiveASTVisitor<InlayHintVisitor> {
 public:
   InlayHintVisitor(std::vector<InlayHint> &Results, ParsedAST &AST)
       : Results(Results), AST(AST.getASTContext()),
NameVec getParameterNamesForDecl(const FunctionDecl *Function,
     return Result;
   }
 
   void addInlayHint(SourceRange R, InlayHintKind Kind, llvm::StringRef Label) {
     auto FileRange =
         toHalfOpenFileRange(AST.getSourceManager(), AST.getLangOpts(), R);
     if (!FileRange)
       return;
+    // The hint may be in a file other than the main file (for example, a header
+    // file that was included after the preamble), do not show in that case.
+    if (!AST.getSourceManager().isWrittenInMainFile(FileRange->getBegin()))
+      return;
     Results.push_back(InlayHint{
         Range{
             sourceLocToPosition(AST.getSourceManager(), FileRange->getBegin()),
             sourceLocToPosition(AST.getSourceManager(), FileRange->getEnd())},
         Kind, Label.str()});
   }
 
   void addTypeHint(SourceRange R, QualType T, llvm::StringRef Prefix) {

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

 //===-- InlayHintTests.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 "InlayHints.h"
 #include "Protocol.h"
 #include "TestTU.h"
+#include "TestWorkspace.h"
 #include "XRefs.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
 namespace clang {
 namespace clangd {
 
 std::ostream &operator<<(std::ostream &Stream, const InlayHint &Hint) {
void bar() {
       // FIXME: Ideally we'd want to omit this.
       s.setTimeoutMillis($timeout_millis[[120]]);
     }
   )cpp",
                        ExpectedHint{"timeoutMillis: ", "timeoutMillis"},
                        ExpectedHint{"timeout_millis: ", "timeout_millis"});
 }
 
+TEST(ParameterHints, IncludeAtNonGlobalScope) {
+  Annotations FooInc(R"cpp(
+    void bar() { foo(42); }
+  )cpp");
+  Annotations FooCC(R"cpp(
+    struct S {
+      void foo(int param);
+      #include "foo.inc"
+    };
+  )cpp");
+
+  TestWorkspace Workspace;
+  Workspace.addSource("foo.inc", FooInc.code());
+  Workspace.addMainFile("foo.cc", FooCC.code());
+
+  auto AST = Workspace.openFile("foo.cc");
+  ASSERT_TRUE(bool(AST));
+
+  // Ensure the hint for the call in foo.inc is NOT materialized in foo.cc.
+  EXPECT_EQ(hintsOfKind(*AST, InlayHintKind::ParameterHint).size(), 0u);
+}
+
 TEST(TypeHints, Smoke) {
   assertTypeHints(R"cpp(
     auto $waldo[[waldo]] = 42;
   )cpp",
                   ExpectedHint{": int", "waldo"});
 }
 
 TEST(TypeHints, Decorations) {

 //  - auto x = llvm::dyn_cast<LongTypeName>(y);  // and similar
 //  - stdlib algos return unwieldy __normal_iterator<X*, ...> type
 //    (For this one, perhaps we should omit type hints that start
 //     with a double underscore.)
 
 } // namespace
 } // namespace clangd
 } // namespace clang
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