[clang] [clang][bytecode] Fix crash in void functions returning non-void expr… (PR #176550)

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https://github.com/Serosh-commits updated https://github.com/llvm/llvm-project/pull/176550

>From 8cdc2554db36c455c651bc9221c3e15b2f6ecbed Mon Sep 17 00:00:00 2001
From: Serosh <janmejayapanda400 at gmail.com>
Date: Sat, 17 Jan 2026 15:57:11 +0530
Subject: [PATCH] [clang][bytecode] Fix crash in void functions returning
 non-void expressions

The bytecode compiler was erroneously emitting an RVOPtr opcode for
void functions when they contained a non-void return expression.
This led to an assertion failure in the interpreter.

This fix ensures that discard() is used instead of visit() for such
expressions in void functions, and prevents the emission of RVO pointers.
It checks RE->containsErrors() to handle invalid return expressions
gracefully.

Fixes #176536
---
 clang/lib/AST/ByteCode/Compiler.cpp   | 5 +++--
 clang/test/AST/ByteCode/functions.cpp | 7 +++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index 21f8db06919ed..19386a045d121 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -5678,8 +5678,9 @@ bool Compiler<Emitter>::visitReturnStmt(const ReturnStmt *RS) {
       return this->emitRet(*ReturnType, RS);
     }
 
-    if (RE->getType()->isVoidType()) {
-      if (!this->visit(RE))
+    if (RE->containsErrors() || RE->getType()->isVoidType() ||
+        (CompilingFunction && CompilingFunction->getReturnType()->isVoidType())) {
+      if (!this->discard(RE))
         return false;
     } else {
       InitLinkScope<Emitter> ILS(this, InitLink::RVO());
diff --git a/clang/test/AST/ByteCode/functions.cpp b/clang/test/AST/ByteCode/functions.cpp
index 21d3ddaafaee3..7fba1150ab736 100644
--- a/clang/test/AST/ByteCode/functions.cpp
+++ b/clang/test/AST/ByteCode/functions.cpp
@@ -735,3 +735,10 @@ namespace PtrPtrCast {
   void foo() { ; }
   void bar(int *a) { a = (int *)(void *)(foo); }
 }
+
+namespace GH176536 {
+  constexpr void foo(int n) {
+    return n > 1 ? foo(n - 1) : 0; // expected-error {{return type 'void' must match the return type 'int' of the expression}}
+  }
+  static_assert((foo(2), true), "");
+}