The lvalue-to-rvalue on structs in C++ is actually part

of default argument promotion and needs to happen unconditionally.
This is particularly semantically important in C++0x.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@138691 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 42 insertions, 17 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 530f81289a..30c247f987 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -12,6 +12,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/Sema/Initialization.h"
 #include "clang/Sema/Sema.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/ScopeInfo.h"
@@ -396,6 +397,30 @@ bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
   return false;
 }
 
+/// checkBuiltinArgument - Given a call to a builtin function, perform
+/// normal type-checking on the given argument, updating the call in
+/// place.  This is useful when a builtin function requires custom
+/// type-checking for some of its arguments but not necessarily all of
+/// them.
+///
+/// Returns true on error.
+static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
+  FunctionDecl *Fn = E->getDirectCallee();
+  assert(Fn && "builtin call without direct callee!");
+
+  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
+  InitializedEntity Entity =
+    InitializedEntity::InitializeParameter(S.Context, Param);
+
+  ExprResult Arg = E->getArg(0);
+  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
+  if (Arg.isInvalid())
+    return true;
+
+  E->setArg(ArgIndex, Arg.take());
+  return false;
+}
+
 /// SemaBuiltinAtomicOverloaded - We have a call to a function like
 /// __sync_fetch_and_add, which is an overloaded function based on the pointer
 /// type of its first argument.  The main ActOnCallExpr routines have already
@@ -661,6 +686,10 @@ bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
       << 0 /*function call*/ << 2 << TheCall->getNumArgs();
   }
 
+  // Type-check the first argument normally.
+  if (checkBuiltinArgument(*this, TheCall, 0))
+    return true;
+
   // Determine whether the current function is variadic or not.
   BlockScopeInfo *CurBlock = getCurBlock();
   bool isVariadic;
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 28ec97f652..65c9cccaf1 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -443,6 +443,18 @@ ExprResult Sema::DefaultArgumentPromotion(Expr *E) {
   if (Ty->isSpecificBuiltinType(BuiltinType::Float))
     E = ImpCastExprToType(E, Context.DoubleTy, CK_FloatingCast).take();
 
+  // C++ includes lvalue-to-rvalue conversion as a default argument
+  // promotion.  If we have a gl-value, initialize a temporary.
+  if (getLangOptions().CPlusPlus && E->isGLValue()) {
+    ExprResult Temp = PerformCopyInitialization(
+                       InitializedEntity::InitializeTemporary(E->getType()),
+                                                E->getExprLoc(),
+                                                Owned(E));
+    if (Temp.isInvalid())
+      return ExprError();
+    E = Temp.get();
+  }
+
   return Owned(E);
 }
 
@@ -460,19 +472,13 @@ ExprResult Sema::DefaultVariadicArgumentPromotion(Expr *E, VariadicCallType CT,
     return ExprError();
   E = ExprRes.take();
 
-  // __builtin_va_start takes the second argument as a "varargs" argument, but
-  // it doesn't actually do anything with it.  It doesn't need to be non-pod
-  // etc.
-  if (FDecl && FDecl->getBuiltinID() == Builtin::BI__builtin_va_start)
-    return Owned(E);
-  
   // Don't allow one to pass an Objective-C interface to a vararg.
   if (E->getType()->isObjCObjectType() &&
     DiagRuntimeBehavior(E->getLocStart(), 0,
                         PDiag(diag::err_cannot_pass_objc_interface_to_vararg)
                           << E->getType() << CT))
     return ExprError();
-  
+
   if (!E->getType().isPODType(Context)) {
     // C++0x [expr.call]p7:
     //   Passing a potentially-evaluated argument of class type (Clause 9) 
@@ -519,16 +525,6 @@ ExprResult Sema::DefaultVariadicArgumentPromotion(Expr *E, VariadicCallType CT,
       if (Comma.isInvalid())
         return ExprError();      
       E = Comma.get();
-
-      // Use that to initialize a temporary, or else we might get an
-      // l-value in a varargs position.
-      ExprResult Temp = PerformCopyInitialization(
-                       InitializedEntity::InitializeTemporary(E->getType()),
-                                                  E->getLocStart(),
-                                                  Owned(E));
-      if (Temp.isInvalid())
-        return ExprError();
-      E = Temp.get();
     }
   }