[clang][bytecode] Avoid revisiting decomposition decl in visitDeclRef (#144226)

This simple patch removes the code to revisit `DecompositionDecl` in
`visitDeclRef`. The revisit will try to emit the initializer of the
`DecompositionDecl`, which could result in evaluation errors if the
`DecompositionDecl` is not within a constexpr context.

Author: Lancern

clang/lib/AST/ByteCode/Compiler.cpp

@@ -6591,10 +6591,6 @@ bool Compiler<Emitter>::visitDeclRef(const ValueDecl *D, const Expr *E) {
     return T->isReferenceType();
   };
 
-  // DecompositionDecls are just proxies for us.
-  if (isa<DecompositionDecl>(VD))
-    return revisit(VD);
-
   if ((VD->hasGlobalStorage() || VD->isStaticDataMember()) &&
       typeShouldBeVisited(VD->getType())) {
     if (const Expr *Init = VD->getAnyInitializer();

clang/test/AST/ByteCode/cxx17.cpp

@@ -141,3 +141,11 @@ template <int x> constexpr auto c() {
 }
 
 auto y = c<1>(); // both-note {{in instantiation of function template specialization 'c<1>' requested here}}
+
+namespace NonConstexprStructuredBinding {
+  void f1() {
+    int arr[2] = {};
+    auto [a, b] = arr;
+    static_assert(&a != &b);
+  }
+}