[clang][Interp] Bail out on missing ComparisonCategoryInfo

[tbaederr]

Instead of asserting. This can happen in real-world code.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

Changes

Instead of asserting. This can happen in real-world code.

---

Full diff: https://github.com/llvm/llvm-project/pull/80131.diff

2 Files Affected:

• (modified) clang/lib/AST/Interp/ByteCodeExprGen.cpp (+2-1)
• (modified) clang/test/Sema/struct-cast.c (+1)

diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
index 8188d6f7f5c24..a1c458a09e5ae 100644
--- a/clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -379,7 +379,8 @@ bool ByteCodeExprGen<Emitter>::VisitBinaryOperator(const BinaryOperator *BO) {
       return true;
     const ComparisonCategoryInfo *CmpInfo =
         Ctx.getASTContext().CompCategories.lookupInfoForType(BO->getType());
-    assert(CmpInfo);
+    if (!CmpInfo)
+      return false;
 
     // We need a temporary variable holding our return value.
     if (!Initializing) {
diff --git a/clang/test/Sema/struct-cast.c b/clang/test/Sema/struct-cast.c
index 74d00c42c295e..05e5fa4f92ca7 100644
--- a/clang/test/Sema/struct-cast.c
+++ b/clang/test/Sema/struct-cast.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only %s -verify
+// RUN: %clang_cc1 -fsyntax-only %s -fexperimental-new-constant-interpreter -verify
 // expected-no-diagnostics
 
 struct S {

[tbaederr]

Ping

[AaronBallman]

I'm really confused what this test has to do with the changes above. The changes relate to three-way comparison operators but this test is a C test file and has no comparison operators involved. Why would this test hit that assertion?

[tbaederr]

The AST we trip up on is

BinaryOperator 0x52100006ed08 'struct S' '='
|-DeclRefExpr 0x52100006eba0 'struct S' lvalue Var 0x52100006e998 'tmp' 'struct S'
`-CStyleCastExpr 0x52100006ecd8 'struct S' <NoOp>
  `-CallExpr 0x52100006ec88 'struct S'
    `-ImplicitCastExpr 0x52100006ec68 'const struct S (*)(void)' <FunctionToPointerDecay>
      `-DeclRefExpr 0x52100006ebc8 'const struct S (void)' Function 0x52100006e870 'foo' 'const struct S (void)'

IIUC this should be rejected since the assignment doesn't work, but we're asserting that we found CmpInfo. We could of course also add more assertions that we're even in C++ mode when looking for the spaceship operator stuff.

[AaronBallman]

Why should this assignment not work? (The code looks valid to me). Oh, wait, you mean this assignment shouldn't be a constant expression? (If so, I agree.)

That said, I see now why we're hitting the assertion on an assignment operator in C; the call to lookupInfoForType() will return nullptr in that case and we need to handle that.

I don't think we want to look for the spaceship operator stuff outside of C++ mode, but that can be done in a follow-up as this is fixing a failing assertion.

[tbaederr]

Yes, what I mean is, the constant interpreter should return false for this assignment in C.

[AaronBallman]

Excellent, thank you!

[AaronBallman]

LGTM!

[AaronBallman]

Excellent, thank you!