https://github.com/necto created https://github.com/llvm/llvm-project/pull/196298
`-fvalidate-ast-input-files-content` is silently ignored when loading PCH files for additional translation units. This triggers an import failure when modification time of some of input files changes (for example, the AST dump is being reused for a subsequent cross-translation-unit re-analysis with Clang Static Analyzer after a fresh code checkout). This makes it difficult to use cached AST dumps. This patch enables the user to control validation of AST input files, without imposing it on them. -- CPP-8025 >From fc1e8b138b8f7a826eb2d79789cb44c518be727a Mon Sep 17 00:00:00 2001 From: Arseniy Zaostrovnykh <[email protected]> Date: Thu, 7 May 2026 14:01:31 +0200 Subject: [PATCH 1/2] Demonstrate CTU import failure when mtime is advanced --- clang/test/Analysis/ctu/reusable-pch.c | 42 ++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 clang/test/Analysis/ctu/reusable-pch.c diff --git a/clang/test/Analysis/ctu/reusable-pch.c b/clang/test/Analysis/ctu/reusable-pch.c new file mode 100644 index 0000000000000..6f42cd3c90097 --- /dev/null +++ b/clang/test/Analysis/ctu/reusable-pch.c @@ -0,0 +1,42 @@ +// RUN: rm -rf %t +// RUN: mkdir -p %t +// RUN: split-file %s %t + +// Step 1: Build PCH and defmap. +// RUN: %clang_cc1 -x c -emit-pch -o %t/other.c.ast %t/other.c +// RUN: %clang_extdef_map %t/other.c -- -c -x c > %t/externalDefMap.tmp.txt +// RUN: sed 's| .*other\.c| other.c.ast|' %t/externalDefMap.tmp.txt > %t/externalDefMap.txt + +// Step 2: Run CTU using the PCH - the division by zero is found via inlining. +// RUN: %clang_cc1 -analyze \ +// RUN: -analyzer-checker=core \ +// RUN: -analyzer-config experimental-enable-naive-ctu-analysis=true \ +// RUN: -analyzer-config ctu-dir=%t \ +// RUN: -verify %t/main.c + +// Step 3: Advance mtime of the source from which PCH was built. +// RUN: %python -c "import os, sys, time; os.utime(sys.argv[1], (time.time() + 120, time.time() + 120))" %t/other.c + +// Step 4: Run CTU using the now-stale PCH - it breaks. +// RUN: not %clang_cc1 -analyze \ +// RUN: -analyzer-checker=core \ +// RUN: -analyzer-config experimental-enable-naive-ctu-analysis=true \ +// RUN: -analyzer-config ctu-dir=%t \ +// RUN: %t/main.c 2>&1 | FileCheck --check-prefix=BREAKS %s + +// BREAKS: file '{{.*}}other.c' has been modified since the precompiled file '{{.*}}other.c.ast' was built + +//--- main.c +// Without CTU, always_zero() has an unknown return value so no bug is found. +// With CTU, always_zero() is inlined and its return value (0) is known, +// exposing the division by zero. + +int always_zero(void); + +void f(void) { + int x = always_zero(); + (void)(1 / x); // expected-warning{{Division by zero}} +} + +//--- other.c +int always_zero(void) { return 0; } >From 83753d63db8230563f2203497b59b73c5a1782b1 Mon Sep 17 00:00:00 2001 From: Arseniy Zaostrovnykh <[email protected]> Date: Thu, 7 May 2026 14:08:29 +0200 Subject: [PATCH 2/2] Forward ValidateASTInputFilesContent when importing AST dumps --- clang/lib/Frontend/ASTUnit.cpp | 8 +++++++- clang/test/Analysis/ctu/reusable-pch.c | 10 +++++----- 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp index 05ae1f348f920..8003b72e0619d 100644 --- a/clang/lib/Frontend/ASTUnit.cpp +++ b/clang/lib/Frontend/ASTUnit.cpp @@ -780,11 +780,17 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile( DisableValidationForModuleKind::None; if (::getenv("LIBCLANG_DISABLE_PCH_VALIDATION")) disableValid = DisableValidationForModuleKind::All; + bool ValidateASTInputFilesContent = HSOpts.ValidateASTInputFilesContent; + AST->Reader = llvm::makeIntrusiveRefCnt<ASTReader>( *AST->PP, *AST->ModCache, AST->Ctx.get(), PCHContainerRdr, *AST->CodeGenOpts, ArrayRef<std::shared_ptr<ModuleFileExtension>>(), /*isysroot=*/"", - /*DisableValidationKind=*/disableValid, AllowASTWithCompilerErrors); + /*DisableValidationKind=*/disableValid, AllowASTWithCompilerErrors, + /*AllowConfigurationMismatch=*/ false, + /*ValidateSystemInputs=*/ false, + /*ForceValidateUserInputs=*/ false, + ValidateASTInputFilesContent); // Attach the AST reader to the AST context as an external AST source, so that // declarations will be deserialized from the AST file as needed. diff --git a/clang/test/Analysis/ctu/reusable-pch.c b/clang/test/Analysis/ctu/reusable-pch.c index 6f42cd3c90097..92256b9f0156c 100644 --- a/clang/test/Analysis/ctu/reusable-pch.c +++ b/clang/test/Analysis/ctu/reusable-pch.c @@ -3,12 +3,13 @@ // RUN: split-file %s %t // Step 1: Build PCH and defmap. -// RUN: %clang_cc1 -x c -emit-pch -o %t/other.c.ast %t/other.c +// RUN: %clang_cc1 -x c -emit-pch -fvalidate-ast-input-files-content -o %t/other.c.ast %t/other.c // RUN: %clang_extdef_map %t/other.c -- -c -x c > %t/externalDefMap.tmp.txt // RUN: sed 's| .*other\.c| other.c.ast|' %t/externalDefMap.tmp.txt > %t/externalDefMap.txt // Step 2: Run CTU using the PCH - the division by zero is found via inlining. // RUN: %clang_cc1 -analyze \ +// RUN: -fvalidate-ast-input-files-content \ // RUN: -analyzer-checker=core \ // RUN: -analyzer-config experimental-enable-naive-ctu-analysis=true \ // RUN: -analyzer-config ctu-dir=%t \ @@ -18,13 +19,12 @@ // RUN: %python -c "import os, sys, time; os.utime(sys.argv[1], (time.time() + 120, time.time() + 120))" %t/other.c // Step 4: Run CTU using the now-stale PCH - it breaks. -// RUN: not %clang_cc1 -analyze \ +// RUN: %clang_cc1 -analyze \ +// RUN: -fvalidate-ast-input-files-content \ // RUN: -analyzer-checker=core \ // RUN: -analyzer-config experimental-enable-naive-ctu-analysis=true \ // RUN: -analyzer-config ctu-dir=%t \ -// RUN: %t/main.c 2>&1 | FileCheck --check-prefix=BREAKS %s - -// BREAKS: file '{{.*}}other.c' has been modified since the precompiled file '{{.*}}other.c.ast' was built +// RUN: %t/main.c //--- main.c // Without CTU, always_zero() has an unknown return value so no bug is found. _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
