[clang] [clang][bytecode] Fix ignoring comparisons in C (PR #156180)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

<details>
<summary>Changes</summary>

Our comparison ops always return bool, and we do the pop before the conversion to in in C.

Fixes #<!-- -->156178

---
Full diff: https://github.com/llvm/llvm-project/pull/156180.diff


2 Files Affected:

- (modified) clang/lib/AST/ByteCode/Compiler.cpp (+1-1) 
- (modified) clang/test/AST/ByteCode/c.c (+6) 


``````````diff
diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index c314f0a132196..56552f3969216 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -942,7 +942,7 @@ bool Compiler<Emitter>::VisitBinaryOperator(const BinaryOperator *BO) {
     if (!Result)
       return false;
     if (DiscardResult)
-      return this->emitPop(*T, BO);
+      return this->emitPopBool(BO);
     if (T != PT_Bool)
       return this->emitCast(PT_Bool, *T, BO);
     return true;
diff --git a/clang/test/AST/ByteCode/c.c b/clang/test/AST/ByteCode/c.c
index 05af00c040f45..b6d2a69271afb 100644
--- a/clang/test/AST/ByteCode/c.c
+++ b/clang/test/AST/ByteCode/c.c
@@ -362,3 +362,9 @@ void bar() { // pedantic-warning {{a function declaration without a prototype}}
   int x;
   x = foo(); // all-warning {{too few arguments}}
 }
+
+int *_b = &a;
+void discardedCmp(void)
+{
+    (*_b) = ((&a == &a) , a); // all-warning {{left operand of comma operator has no effect}}
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/156180