[clang] Fix crash when inheriting from a cv-qualified type

[Rajveer100]

Resolves Issue #35603

This change makes the assertion less strict in debug builds by stripping qualifiers from the base class and ignoring them. I hope weakened assertions don't affect other cases where such errors are intended to be caught by the compiler.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Rajveer Singh Bharadwaj (Rajveer100)

Changes

Resolves Issue #35603

This change makes the assertion less strict in debug builds by stripping qualifiers from the base class and ignoring them. I hope weakened assertions don't affect other cases where such errors are intended to be caught by the compiler.

---

Full diff: https://github.com/llvm/llvm-project/pull/70594.diff

2 Files Affected:

• (modified) clang/lib/AST/ExprConstant.cpp (+1-1)
• (added) clang/test/Sema/assertion-crash.cpp (+19)

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 5947805f9576ff8..07f0a12385b46e9 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -6431,7 +6431,7 @@ static bool HandleConstructorCall(const Expr *E, const LValue &This,
       // Non-virtual base classes are initialized in the order in the class
       // definition. We have already checked for virtual base classes.
       assert(!BaseIt->isVirtual() && "virtual base for literal type");
-      assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
+      assert(Info.Ctx.hasSameUnqualifiedType(BaseIt->getType(), BaseType) &&
              "base class initializers not in expected order");
       ++BaseIt;
 #endif
diff --git a/clang/test/Sema/assertion-crash.cpp b/clang/test/Sema/assertion-crash.cpp
new file mode 100644
index 000000000000000..853552108ec2b67
--- /dev/null
+++ b/clang/test/Sema/assertion-crash.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++11 %s -verify
+// RUN: %clang_cc1 -fsyntax-only -std=c++23 %s -verify
+
+// expected-no-diagnostics
+
+struct A {};
+using CA = const A;
+
+struct S1 : CA {
+  constexpr S1() : CA() {}
+};
+
+struct S2 : A {
+  constexpr S2() : CA() {}
+};
+
+struct S3 : CA {
+  constexpr S3() : A() {}
+};

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[Rajveer100]

The clang-format issues showing up for changes are not related to this PR.

[cor3ntin]

LGTM too. Please add a release note though

[Rajveer100]

@cor3ntin
Could you describe the format of the release note briefly so I can amend my commit accordingly?

[xgupta]

@cor3ntin Could you describe the format of the release note briefly so I can amend my commit accordingly?
Like this -
https://github.com/llvm/llvm-project/pull/74553/files#diff-ec770381d76c859f5f572db789175fe44410a72608f58ad5dbb14335ba56eb97

You also need to clang-format this patch with git clang-format HEAD~1.

[Rajveer100]

@cor3ntin
Could you help me in closing this?

[cor3ntin]

LGTM

[Endilll]

You might want to include a test from #85256 (comment)

[Rajveer100]

@shafik
Could you land this for me?

[Endilll]

I can land this for you after CI passes.

[yronglin]

#85256 can be closed once this PR merged.