https://github.com/higher-performance updated
https://github.com/llvm/llvm-project/pull/148692
>From 668c02da2d472c6d13981cd7fdb258419d0ffb05 Mon Sep 17 00:00:00 2001
From: higher-performance <higher.performance.git...@gmail.com>
Date: Mon, 14 Jul 2025 14:05:07 -0400
Subject: [PATCH] Check if clang::FieldDecl has constant-integer bit width
before getting the width, to avoid crashing inside templates
---
clang/docs/ReleaseNotes.rst | 2 ++
clang/include/clang/AST/Decl.h | 5 +++++
clang/include/clang/ASTMatchers/ASTMatchers.h | 3 ++-
clang/lib/AST/Decl.cpp | 9 ++++++---
.../ASTMatchers/ASTMatchersNarrowingTest.cpp | 13 +++++++++++++
5 files changed, 28 insertions(+), 4 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 57a94242c9e61..0171fb03505cc 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -1088,6 +1088,8 @@ Fixed Point Support in Clang
AST Matchers
------------
+- Ensure ``hasBitWidth`` doesn't crash on bit widths that are dependent on
template
+ parameters.
- Ensure ``isDerivedFrom`` matches the correct base in case more than one
alias exists.
- Extend ``templateArgumentCountIs`` to support function and variable template
specialization.
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index f70a039bf3517..f88c206ca4d44 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -3234,6 +3234,11 @@ class FieldDecl : public DeclaratorDecl, public
Mergeable<FieldDecl> {
return hasInClassInitializer() ? InitAndBitWidth->BitWidth : BitWidth;
}
+ /// Determines whether the bit width of this field is a constant integer.
+ /// This may not always be the case, such as inside template-dependent
+ /// expressions.
+ bool hasConstantIntegerBitWidth() const;
+
/// Computes the bit width of this field, if this is a bit field.
/// May not be called on non-bitfields.
/// Note that in order to successfully use this function, the bitwidth
diff --git a/clang/include/clang/ASTMatchers/ASTMatchers.h
b/clang/include/clang/ASTMatchers/ASTMatchers.h
index bae004896c11f..fcce9b5c38b23 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchers.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -709,7 +709,8 @@ AST_MATCHER(FieldDecl, isBitField) {
/// fieldDecl(hasBitWidth(2))
/// matches 'int a;' and 'int c;' but not 'int b;'.
AST_MATCHER_P(FieldDecl, hasBitWidth, unsigned, Width) {
- return Node.isBitField() && Node.getBitWidthValue() == Width;
+ return Node.isBitField() && Node.hasConstantIntegerBitWidth() &&
+ Node.getBitWidthValue() == Width;
}
/// Matches non-static data members that have an in-class initializer.
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 8855d0107daca..f4cb5a026e25f 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4677,11 +4677,14 @@ void
FieldDecl::setLazyInClassInitializer(LazyDeclStmtPtr NewInit) {
Init = NewInit;
}
+bool FieldDecl::hasConstantIntegerBitWidth() const {
+ const auto *CE = dyn_cast_if_present<ConstantExpr>(getBitWidth());
+ return CE && CE->getAPValueResult().isInt();
+}
+
unsigned FieldDecl::getBitWidthValue() const {
assert(isBitField() && "not a bitfield");
- assert(isa<ConstantExpr>(getBitWidth()));
- assert(cast<ConstantExpr>(getBitWidth())->hasAPValueResult());
- assert(cast<ConstantExpr>(getBitWidth())->getAPValueResult().isInt());
+ assert(hasConstantIntegerBitWidth());
return cast<ConstantExpr>(getBitWidth())
->getAPValueResult()
.getInt()
diff --git a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
b/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
index 49abe881eeabb..287122393446d 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -2925,6 +2925,19 @@ TEST_P(ASTMatchersTest, IsBitField) {
fieldDecl(isBitField(), hasName("b"))));
EXPECT_TRUE(matches("struct C { int a : 2; int b : 4; };",
fieldDecl(isBitField(), hasBitWidth(2), hasName("a"))));
+ if (GetParam().isCXX()) {
+ // This test verifies 2 things:
+ // (1) That templates work correctly.
+ // (2) That the matcher does not crash on template-dependent bit widths.
+ EXPECT_TRUE(matches("template<int N> "
+ "struct C { "
+ "explicit C(bool x) : a(x) { } "
+ "int a : N; "
+ "int b : 4; "
+ "}; "
+ "template struct C<2>;",
+ fieldDecl(isBitField(), hasBitWidth(2),
hasName("a"))));
+ }
}
TEST_P(ASTMatchersTest, HasInClassInitializer) {
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