https://github.com/ziqingluo-90 created
https://github.com/llvm/llvm-project/pull/205430
`GenLoc` previously printed the source location at most once per USR, gated by
a member flag toggled on the first call. During the recursive visit, if both
an outer and an inner decl needed to print the location, only the outer one was
printed. When the outer decl did not need the offset, no offset was ever
printed. For example, the USR of `Holder<decltype([]{})>::method` depends on
the location of the type of the lambda but the outer decl prints the file entry
only, which disables offset printing.
Change the logic so the file-entry part of the location is printed at most once
(it must be identical), while offsets of sub-decl locations may be printed
multiple times.
>From 0ca87a1c6d60ebaa9369283a8ad21450e209f7e3 Mon Sep 17 00:00:00 2001
From: Ziqing Luo <[email protected]>
Date: Tue, 23 Jun 2026 13:17:16 -0700
Subject: [PATCH] [clang-index][USR] GenLoc prints file entry at most once,
allow repeated offsets
GenLoc previously printed the source location at most once per USR,
gated by a member flag toggled on the first call. During the
recursive visit, if both an outer and an inner decl needed to print
the location, only the outer one was printed. When the outer decl did
not need the offset, no offset was ever printed. For example, the USR
of `Holder<decltype([]{})>::method` depends on the location of the
type of the lambda but the outer decl prints the file entry only,
which disables offset printing.
Change the logic so the file-entry part of the location is printed at
most once (it must be identical), while offsets of sub-decl locations
may be printed multiple times.
---
.../UnifiedSymbolResolution/USRGeneration.cpp | 45 ++++++++++++++-----
clang/unittests/Index/IndexTests.cpp | 34 ++++++++++++++
2 files changed, 69 insertions(+), 10 deletions(-)
diff --git a/clang/lib/UnifiedSymbolResolution/USRGeneration.cpp
b/clang/lib/UnifiedSymbolResolution/USRGeneration.cpp
index c4788dd6917f2..7c254e0c39c32 100644
--- a/clang/lib/UnifiedSymbolResolution/USRGeneration.cpp
+++ b/clang/lib/UnifiedSymbolResolution/USRGeneration.cpp
@@ -24,6 +24,22 @@ using namespace clang::index;
// USR generation.
//===----------------------------------------------------------------------===//
+/// Print only the offset part of \p Loc
+/// \returns true on error.
+static bool printLocOffset(llvm::raw_ostream &OS, SourceLocation Loc,
+ const SourceManager &SM) {
+ if (Loc.isInvalid())
+ return true;
+ Loc = SM.getExpansionLoc(Loc);
+ // Use the offest into the FileID to represent the location. Using
+ // a line/column can cause us to look back at the original source file,
+ // which is expensive.
+ OS << '@' << SM.getDecomposedLoc(Loc).second;
+ return false;
+}
+
+/// Print \p Loc including both the file and offset, if \p IncludeOffset is
+/// true. Print only the file of \p Loc otherwise.
/// \returns true on error.
static bool printLoc(llvm::raw_ostream &OS, SourceLocation Loc,
const SourceManager &SM, bool IncludeOffset) {
@@ -64,7 +80,11 @@ class USRGenerator : public ConstDeclVisitor<USRGenerator> {
ASTContext *Context;
const LangOptions &LangOpts;
bool IgnoreResults = false;
- bool generatedLoc = false;
+ // The flag below ensures that, when a source location needs to be printed,
+ // the file entry is printed at most once during the recursive visit. The
+ // offset part may be printed multiple times, since sub-decls along the
+ // path may each need a distinct location to disambiguate them.
+ bool GeneratedFileEntry = false;
llvm::DenseMap<const Type *, unsigned> TypeSubstitutions;
@@ -636,23 +656,28 @@ void USRGenerator::GenExtSymbolContainer(const NamedDecl
*D) {
}
bool USRGenerator::GenLoc(const Decl *D, bool IncludeOffset) {
- if (generatedLoc)
- return IgnoreResults;
- generatedLoc = true;
-
// Guard against null declarations in invalid code.
if (!D) {
IgnoreResults = true;
return true;
}
+ // Do nothing if file entry has been printed and no need to print the offset.
+ if (GeneratedFileEntry && !IncludeOffset)
+ return IgnoreResults;
+
+ bool PrintErr = false;
// Use the location of canonical decl.
D = D->getCanonicalDecl();
-
- IgnoreResults =
- IgnoreResults || printLoc(Out, D->getBeginLoc(),
- Context->getSourceManager(), IncludeOffset);
-
+ if (!GeneratedFileEntry) {
+ GeneratedFileEntry = true;
+ PrintErr = printLoc(Out, D->getBeginLoc(), Context->getSourceManager(),
+ IncludeOffset);
+ } else {
+ PrintErr =
+ printLocOffset(Out, D->getBeginLoc(), Context->getSourceManager());
+ }
+ IgnoreResults = IgnoreResults || PrintErr;
return IgnoreResults;
}
diff --git a/clang/unittests/Index/IndexTests.cpp
b/clang/unittests/Index/IndexTests.cpp
index 6df4b577d98a0..90d47657fc5cc 100644
--- a/clang/unittests/Index/IndexTests.cpp
+++ b/clang/unittests/Index/IndexTests.cpp
@@ -9,6 +9,7 @@
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
+#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Frontend/CompilerInstance.h"
@@ -18,6 +19,7 @@
#include "clang/Index/IndexingAction.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Tooling/Tooling.h"
+#include "clang/UnifiedSymbolResolution/USRGeneration.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "gmock/gmock.h"
@@ -451,6 +453,38 @@ TEST(IndexTest, ReadWriteRoles) {
WrittenAt(Position(6, 17))))));
}
+// Two `Holder<decltype([]{})>` instantiations have distinct closure types,
+// therefore they should have distinct USRs.
+TEST(USRTest, NestedLambdaTagsInTemplateArgGetDistinctUSRs) {
+ auto AST = tooling::buildASTFromCodeWithArgs(
+ R"cpp(
+ template <class T> struct Holder { void reset(T*) {} };
+ void caller() {
+ Holder<decltype([]{})>().reset(nullptr);
+ Holder<decltype([]{})>().reset(nullptr);
+ }
+ )cpp",
+ {"-std=c++20"});
+ ASSERT_TRUE(AST);
+
+ struct Visitor : RecursiveASTVisitor<Visitor> {
+ std::vector<const ClassTemplateSpecializationDecl *> Specs;
+ bool VisitCXXMemberCallExpr(CXXMemberCallExpr *Call) {
+ if (auto *M = Call->getMethodDecl())
+ if (auto *S =
dyn_cast<ClassTemplateSpecializationDecl>(M->getParent()))
+ Specs.push_back(S);
+ return true;
+ }
+ } V;
+ V.TraverseAST(AST->getASTContext());
+ ASSERT_EQ(V.Specs.size(), 2u);
+
+ llvm::SmallString<128> U0, U1;
+ ASSERT_FALSE(generateUSRForDecl(V.Specs[0], U0));
+ ASSERT_FALSE(generateUSRForDecl(V.Specs[1], U1));
+ EXPECT_NE(U0, U1) << "U0=" << U0.str() << " U1=" << U1.str();
+}
+
} // namespace
} // namespace index
} // namespace clang
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