[clang] [clang] Forward `-fvalidate-ast-input-files-content` when loading an AST dump (PR #196298)

[Arseniy Zaostrovnykh via cfe-commits]

https://github.com/necto updated https://github.com/llvm/llvm-project/pull/196298

>From fc1e8b138b8f7a826eb2d79789cb44c518be727a Mon Sep 17 00:00:00 2001
From: Arseniy Zaostrovnykh <necto.ne at gmail.com>
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 5aebb6266f50abda207076c459ca88fc600143b0 Mon Sep 17 00:00:00 2001
From: Arseniy Zaostrovnykh <necto.ne at gmail.com>
Date: Thu, 7 May 2026 14:08:29 +0200
Subject: [PATCH 2/2] Forward ValidateASTInputFilesContent when importing AST
 dumps

---
 clang/lib/Frontend/ASTUnit.cpp         |  7 ++++++-
 clang/test/Analysis/ctu/reusable-pch.c | 12 ++++++------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 05ae1f348f920..df6f85560227f 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -780,11 +780,16 @@ 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=*/true, 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..988148692f02f 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 \
@@ -17,14 +18,13 @@
 // 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 \
+// Step 4: Run CTU using the "stale" PCH
+// 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.