https://github.com/hahnjo updated https://github.com/llvm/llvm-project/pull/219189
>From a520ad10573f35dfca27b42847c589d8d9511f88 Mon Sep 17 00:00:00 2001 From: Jonas Hahnfeld <[email protected]> Date: Thu, 27 Aug 2026 13:11:37 +0200 Subject: [PATCH 1/2] [clang][AST] Fix generation with multiple external sources ExternalASTSource::incrementGeneration returns the OldGeneration, which must be taken into account in case it is delegated to the topmost external source. This obsoletes a long-standing downstream patch in Cling that was previously submitted in https://reviews.llvm.org/D39714. --- clang/lib/AST/ExternalASTSource.cpp | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/clang/lib/AST/ExternalASTSource.cpp b/clang/lib/AST/ExternalASTSource.cpp index e8c1004089713..1888ffd6bd27c 100644 --- a/clang/lib/AST/ExternalASTSource.cpp +++ b/clang/lib/AST/ExternalASTSource.cpp @@ -118,19 +118,20 @@ void ExternalASTSource::FindExternalLexicalDecls( void ExternalASTSource::getMemoryBufferSizes(MemoryBufferSizes &sizes) const {} uint32_t ExternalASTSource::incrementGeneration(ASTContext &C) { - uint32_t OldGeneration = CurrentGeneration; - // Make sure the generation of the topmost external source for the context is // incremented. That might not be us. auto *P = C.getExternalSource(); - if (P && P != this) + if (P && P != this) { + // The call itself returns the OldGeneration of the topmost external source. CurrentGeneration = P->incrementGeneration(C); - else { - // FIXME: Only bump the generation counter if the current generation number - // has been observed? - if (!++CurrentGeneration) - llvm::reportFatalUsageError("generation counter overflowed"); } + uint32_t OldGeneration = CurrentGeneration; + + // FIXME: Only bump the generation counter if the current generation number + // has been observed? + if (!++CurrentGeneration) + llvm::reportFatalUsageError("generation counter overflowed"); + return OldGeneration; } >From 2f7eee6c34a7ffac29b42e740e21954c7143775a Mon Sep 17 00:00:00 2001 From: Jonas Hahnfeld <[email protected]> Date: Mon, 31 Aug 2026 17:16:51 +0200 Subject: [PATCH 2/2] Add test Co-authored-by: Vassil Vassilev <[email protected]> Assisted-by: Claude --- clang/unittests/AST/ExternalASTSourceTest.cpp | 43 +++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/clang/unittests/AST/ExternalASTSourceTest.cpp b/clang/unittests/AST/ExternalASTSourceTest.cpp index 19bc143ddb3d3..fa4e96fca8fa3 100644 --- a/clang/unittests/AST/ExternalASTSourceTest.cpp +++ b/clang/unittests/AST/ExternalASTSourceTest.cpp @@ -19,6 +19,7 @@ #include "clang/Frontend/CompilerInvocation.h" #include "clang/Frontend/FrontendActions.h" #include "clang/Lex/PreprocessorOptions.h" +#include "clang/Tooling/Tooling.h" #include "llvm/Support/VirtualFileSystem.h" #include "gtest/gtest.h" @@ -182,3 +183,45 @@ TEST(ExternalASTSourceTest, CompletesPatternInEitherOrder) { EXPECT_EQ(1u, Source->PartialCompletions) << Code; } } + +namespace { +// incrementGeneration is protected, so reaching it needs a source of our own. +struct BumpableSource : ExternalASTSource { + uint32_t bump(ASTContext &C) { return incrementGeneration(C); } +}; +} // namespace + +// Multiple external sources synchronize their generations, and the return +// values of incrementGeneration() and getGeneration() are as expected. This +// is relied upon by ASTReader and LazyGenerationalUpdatePtr. +TEST(ExternalASTSourceTest, IncrementGeneration) { + std::unique_ptr<ASTUnit> AST = tooling::buildASTFromCode(""); + ASSERT_TRUE(AST != nullptr); + ASTContext &Ctx = AST->getASTContext(); + + auto Topmost = llvm::makeIntrusiveRefCnt<BumpableSource>(); + auto Secondary = llvm::makeIntrusiveRefCnt<BumpableSource>(); + Ctx.setExternalSource(Topmost); + ASSERT_EQ(Ctx.getExternalSource(), Topmost.get()); + + // The generation starts at the same value for the two sources. + ASSERT_EQ(Topmost->getGeneration(), 0u); + ASSERT_EQ(Secondary->getGeneration(), 0u); + + // Bumping the "secondary" source bumps the toplevel one, and leaves the two + // agreeing on the generation afterwards. + EXPECT_EQ(Secondary->bump(Ctx), 0u); + EXPECT_EQ(Secondary->getGeneration(), 1u); + EXPECT_EQ(Topmost->getGeneration(), 1u); + + // Bumping the topmost source increments its generation by one. + EXPECT_EQ(Topmost->bump(Ctx), 1u); + EXPECT_EQ(Topmost->getGeneration(), 2u); + // At this point, the "secondary" source is out-of-sync... + EXPECT_EQ(Secondary->getGeneration(), 1u); + + // Another bump synchronizes the two sources. + EXPECT_EQ(Secondary->bump(Ctx), 2u); + EXPECT_EQ(Secondary->getGeneration(), 3u); + EXPECT_EQ(Topmost->getGeneration(), 3u); +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
