[Clang] Fix crash on void{}

[cor3ntin]

Caused by an incorrect assertion.

Fixes #116440

[llvmbot]

@llvm/pr-subscribers-clang-codegen

@llvm/pr-subscribers-clang

Author: Corentin Jabot (cor3ntin)

Changes

Caused by an incorrect assertion.

Fixes #116440

---

Full diff: https://github.com/llvm/llvm-project/pull/147514.diff

2 Files Affected:

• (modified) clang/lib/CodeGen/CGExprScalar.cpp (+3-1)
• (modified) clang/test/CodeGenCXX/cxx0x-initializer-scalars.cpp (+9)

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index fc441dd92d1ee..44931d0481e26 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -2114,8 +2114,10 @@ static int getAsInt32(llvm::ConstantInt *C, llvm::Type *I32Ty) {
 Value *ScalarExprEmitter::VisitInitListExpr(InitListExpr *E) {
   bool Ignore = TestAndClearIgnoreResultAssign();
   (void)Ignore;
-  assert (Ignore == false && "init list ignored");
   unsigned NumInitElements = E->getNumInits();
+  assert(Ignore == false ||
+         (NumInitElements == 0 && E->getType()->isVoidType()) &&
+             "init list ignored");
 
   // HLSL initialization lists in the AST are an expansion which can contain
   // side-effecting expressions wrapped in opaque value expressions. To properly
diff --git a/clang/test/CodeGenCXX/cxx0x-initializer-scalars.cpp b/clang/test/CodeGenCXX/cxx0x-initializer-scalars.cpp
index 2f6a6820a7589..478ad40359727 100644
--- a/clang/test/CodeGenCXX/cxx0x-initializer-scalars.cpp
+++ b/clang/test/CodeGenCXX/cxx0x-initializer-scalars.cpp
@@ -5,3 +5,12 @@ void f()
   // CHECK: store i32 0
   int i{};
 }
+
+
+namespace GH116440 {
+void f() {
+  void{};
+  void();
+}
+
+}

[erichkeane]

Can you add check-lines to this one?

[cor3ntin]

What do you want me to check? noting is emitted

[erichkeane]

Just the function header then CHECK-NEXT: ret void confirms that it actually does nothing/makes it through codegen without going sideways.

So:

// CHECK: define{{.*}} void @{{.*}}GH116440{{.*}}()
// CHECK-NEXT: {{.*}}:
// CHECK-NEXT: ret void

That should work on both windows and itanium manglers, though be more specific on the function name if this test uses a triple.

[erichkeane]

There is no target-triple on this test, so this will fail in windows mode. You can try running it with -triple x86_64-windows-pc to see what I mean.

[cor3ntin]

oups!

[shafik]

I guess we missed a release note?

[brunodf-snps]

This new assert formulation raises a warning in gcc -Wall: https://godbolt.org/z/G8v1zqE4Y
And the grouping of the comment "init list ignored" to only the second condition seems unintended or misleading. Could we revise this?

[erichkeane]

See #158635