P0217R3: Parsing support and framework for AST representation of C++1z

decomposition declarations.

There are a couple of things in the wording that seem strange here:
decomposition declarations are permitted at namespace scope (which we partially
support here) and they are permitted as the declaration in a template (which we
reject).

llvm-svn: 276492

1 files changed, 10 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 0abe75ab2d8..6322e15826a 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -340,10 +340,15 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
 
   // See if this is an auto-typed variable whose initializer we are parsing.
   if (ParsingInitForAutoVars.count(D)) {
-    const AutoType *AT = cast<VarDecl>(D)->getType()->getContainedAutoType();
+    if (isa<BindingDecl>(D)) {
+      Diag(Loc, diag::err_binding_cannot_appear_in_own_initializer)
+        << D->getDeclName();
+    } else {
+      const AutoType *AT = cast<VarDecl>(D)->getType()->getContainedAutoType();
 
-    Diag(Loc, diag::err_auto_variable_cannot_appear_in_own_initializer)
-      << D->getDeclName() << (unsigned)AT->getKeyword();
+      Diag(Loc, diag::err_auto_variable_cannot_appear_in_own_initializer)
+        << D->getDeclName() << (unsigned)AT->getKeyword();
+    }
     return true;
   }
 
@@ -2939,6 +2944,8 @@ ExprResult Sema::BuildDeclarationNameExpr(
     case Decl::Var:
     case Decl::VarTemplateSpecialization:
     case Decl::VarTemplatePartialSpecialization:
+    case Decl::Decomposition:
+    case Decl::Binding:
     case Decl::OMPCapturedExpr:
       // In C, "extern void blah;" is valid and is an r-value.
       if (!getLangOpts().CPlusPlus &&