[clang] [clang][bytecode] Reject void InitListExpr differently (PR #105802)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

<details>
<summary>Changes</summary>

This reverts c79d1fa540390f6e37e1ea326153559eeadd0de6 and 125aa10b3d645bd26523a1bc321bb2e6b1cf04e1

Instead, use the previous approach but allow void-typed InitListExprs with 0 initializers.

---
Full diff: https://github.com/llvm/llvm-project/pull/105802.diff


2 Files Affected:

- (modified) clang/lib/AST/ByteCode/Compiler.cpp (+16-10) 
- (modified) clang/test/AST/ByteCode/c.c (+6-1) 


``````````diff
diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index 3a3927a9671345..b70d6cc8567fbe 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -1344,6 +1344,16 @@ bool Compiler<Emitter>::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
 template <class Emitter>
 bool Compiler<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
                                       const Expr *ArrayFiller, const Expr *E) {
+  QualType QT = E->getType();
+  if (const auto *AT = QT->getAs<AtomicType>())
+    QT = AT->getValueType();
+
+  if (QT->isVoidType()) {
+    if (Inits.size() == 0)
+      return true;
+    return this->emitInvalid(E);
+  }
+
   // Handle discarding first.
   if (DiscardResult) {
     for (const Expr *Init : Inits) {
@@ -1353,13 +1363,6 @@ bool Compiler<Emitter>::visitInitList(ArrayRef<const Expr *> Inits,
     return true;
   }
 
-  QualType QT = E->getType();
-  if (const auto *AT = QT->getAs<AtomicType>())
-    QT = AT->getValueType();
-
-  if (QT->isVoidType())
-    return this->emitInvalid(E);
-
   // Primitive values.
   if (std::optional<PrimType> T = classify(QT)) {
     assert(!DiscardResult);
@@ -3275,9 +3278,12 @@ template <class Emitter> bool Compiler<Emitter>::visit(const Expr *E) {
   if (E->getType().isNull())
     return false;
 
+  if (E->getType()->isVoidType())
+    return this->discard(E);
+
   // Create local variable to hold the return value.
-  if (!E->getType()->isVoidType() && !E->isGLValue() &&
-      !E->getType()->isAnyComplexType() && !classify(E->getType())) {
+  if (!E->isGLValue() && !E->getType()->isAnyComplexType() &&
+      !classify(E->getType())) {
     std::optional<unsigned> LocalIndex = allocateLocal(E);
     if (!LocalIndex)
       return false;
@@ -5171,7 +5177,7 @@ bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
     // We should already have a pointer when we get here.
     return this->delegate(SubExpr);
   case UO_Deref: // *x
-    if (DiscardResult || E->getType()->isVoidType())
+    if (DiscardResult)
       return this->discard(SubExpr);
     return this->visit(SubExpr);
   case UO_Not: // ~x
diff --git a/clang/test/AST/ByteCode/c.c b/clang/test/AST/ByteCode/c.c
index 60f4d6ad1b2967..7cb7f96049f2de 100644
--- a/clang/test/AST/ByteCode/c.c
+++ b/clang/test/AST/ByteCode/c.c
@@ -298,7 +298,6 @@ void T1(void) {
 enum teste1 test1f(void), (*test1)(void) = test1f; // pedantic-warning {{ISO C forbids forward references to 'enum' types}}
 enum teste1 { TEST1 };
 
-
 void func(void) {
   _Static_assert(func + 1 - func == 1, ""); // pedantic-warning {{arithmetic on a pointer to the function type}} \
                                             // pedantic-warning {{arithmetic on pointers to the function type}} \
@@ -313,3 +312,9 @@ void func(void) {
   func - 0xdead000000000000UL; // all-warning {{expression result unused}} \
                                // pedantic-warning {{arithmetic on a pointer to the function type}}
 }
+
+void foo3 (void)
+{
+ void* x = 0;
+ void* y = &*x;
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/105802