[clang][Interp] Handle InitListExprs of composite type

[tbaeder]

Summary

They might appear freestanding, not as part of an initializer. In that
case, we need to create a temporary variable and return a pointer to it.

The test case added doesn't work yet since passing structs by value to functions is broken right now, I will fix that in a follow-up patch.

[tbaeder]

Ping

[tbaeder]

Ping

[tbaeder]

Ping

[tbaeder]

Abandoning in favor of https://reviews.llvm.org/D156027

clang/lib/AST/Interp/ByteCodeExprGen.cpp

if (!this->visit(Index))
     return false;
 
   PrimType IndexT = classifyPrim(Index->getType());
   return this->emitArrayElemPtrPop(IndexT, E);
 }
 
 template <class Emitter>
 bool ByteCodeExprGen<Emitter>::VisitInitListExpr(const InitListExpr *E) {
-  for (const Expr *Init : E->inits()) {
-    if (DiscardResult) {
-      if (!this->discard(Init))
-        return false;
-    } else {
-      if (!this->visit(Init))
-        return false;
-    }
-  }
+  if (std::optional<PrimType> T = classify(E->getType())) {
+    assert(E->getNumInits() == 1);
+    return DiscardResult ? this->discard(E->inits()[0])
+                         : this->visit(E->inits()[0]);
+  }
+
+  if (std::optional<unsigned> LocalIndex = allocateLocal(E, false)) {
+    if (!this->emitGetPtrLocal(*LocalIndex, E))
+
+    if (!this->visitInitializer(E))
+
+    if (DiscardResult)
+      return this->emitPopPtr(E);
     return true;
   }
 
+  // TODO: Array, complex, etc. types might appear here as well.
+
+  return false;
+}
+
 template <class Emitter>
 bool ByteCodeExprGen<Emitter>::VisitSubstNonTypeTemplateParmExpr(
     const SubstNonTypeTemplateParmExpr *E) {
   if (DiscardResult)
     return this->discard(E->getReplacement());
   return this->visit(E->getReplacement());
 }
 

clang/test/AST/Interp/records.cpp

namespace TemporaryObjectExpr {
   }
   /// FIXME: This should also work in C++14, but it needs suport for
   ///   CXXConstructExpr. I think.
 #if __cplusplus > 201402L
   static_assert(foo(F()) == 0, "");
 #endif
 
 }
+
+#if 0
+constexpr bool BPand(BoolPair bp) {
+  return bp.first && bp.second;
+}
+static_assert(BPand(BoolPair{true, false}) == false, "");
+#endif