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.

llvm-svn: 138691

clang/include/clang/Basic/Builtins.def

@@ -389,7 +389,7 @@ BUILTIN(__builtin_constant_p, "i.", "nct")
 BUILTIN(__builtin_classify_type, "i.", "nct")
 BUILTIN(__builtin___CFStringMakeConstantString, "FC*cC*", "nc")
 BUILTIN(__builtin___NSStringMakeConstantString, "FC*cC*", "nc")
-BUILTIN(__builtin_va_start, "vA.", "n")
+BUILTIN(__builtin_va_start, "vA.", "nt")
 BUILTIN(__builtin_va_end, "vA", "n")
 BUILTIN(__builtin_va_copy, "vAA", "n")
 BUILTIN(__builtin_stdarg_start, "vA.", "n")

clang/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;

clang/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();
     }
   }
   

clang/test/CXX/special/class.temporary/p1.cpp

@@ -0,0 +1,37 @@
+// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
+
+namespace test0 {
+  struct A {
+    A() = default;
+    int x;
+    int y;
+
+    A(const A&) = delete; // expected-note {{function has been explicitly marked deleted here}}
+  };
+
+  void foo(...);
+
+  void test() {
+    A a;
+    foo(a); // expected-error {{call to deleted constructor of 'test0::A'}}
+  }
+}
+
+namespace test1 {
+  struct A {
+    A() = default;
+    int x;
+    int y;
+
+  private:
+    A(const A&) = default; // expected-note {{declared private here}}
+  };
+
+  void foo(...);
+
+  void test() {
+    A a;
+    // FIXME: this error about variadics is bogus
+    foo(a); // expected-error {{calling a private constructor of class 'test1::A'}} expected-error {{cannot pass object of non-trivial type 'test1::A' through variadic function}}
+  }
+}

clang/test/CodeGenCXX/varargs.cpp

@@ -1,17 +1,43 @@
-// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm %s -o - | FileCheck %s
+
 // rdar://7309675
 // PR4678
+namespace test0 {
+  // test1 should be compmiled to be a varargs function in the IR even
+  // though there is no way to do a va_begin.  Otherwise, the optimizer
+  // will warn about 'dropped arguments' at the call site.
 
-// test1 should be compmiled to be a varargs function in the IR even
-// though there is no way to do a va_begin.  Otherwise, the optimizer
-// will warn about 'dropped arguments' at the call site.
+  // CHECK: define i32 @_ZN5test05test1Ez(...)
+  int test1(...) {
+    return -1;
+  }
 
-// CHECK: define i32 @_Z5test1z(...)
-int test1(...) {
-  return -1;
+  // CHECK: call i32 (...)* @_ZN5test05test1Ez(i32 0)
+  void test() {
+    test1(0);
+  }
 }
 
-// CHECK: call i32 (...)* @_Z5test1z(i32 0)
-void test() {
-  test1(0);
+namespace test1 {
+  struct A {
+    int x;
+    int y;
+  };
+
+  void foo(...);
+
+  void test() {
+    A x;
+    foo(x);
+  }
+  // CHECK:    define void @_ZN5test14testEv()
+  // CHECK:      [[X:%.*]] = alloca [[A:%.*]], align 4
+  // CHECK-NEXT: [[TMP:%.*]] = alloca [[A]], align 4
+  // CHECK-NEXT: [[T0:%.*]] = bitcast [[A]]* [[TMP]] to i8*
+  // CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[X]] to i8*
+  // CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* [[T0]], i8* [[T1]], i64 8, i32 4, i1 false)
+  // CHECK-NEXT: [[T0:%.*]] = bitcast [[A]]* [[TMP]] to i64*
+  // CHECK-NEXT: [[T1:%.*]] = load i64* [[T0]], align 1
+  // CHECK-NEXT: call void (...)* @_ZN5test13fooEz(i64 [[T1]])
+  // CHECK-NEXT: ret void
 }