[cfe-commits] r131805 - in /cfe/trunk: lib/Sema/SemaExpr.cpp test/CodeGenCXX/vararg-non-pod.cpp test/SemaCXX/vararg-non-pod.cpp

[Douglas Gregor]

Author: dgregor
Date: Sat May 21 14:26:31 2011
New Revision: 131805

URL: http://llvm.org/viewvc/llvm-project?rev=131805&view=rev
Log:
Fix our handling of the warning when one tries to pass a
non-POD/non-trivial object throuugh a C-style varargs. The warning
itself was default-mapped to error, but can be downgraded, but we were
treating it in Sema like a hard error, silently dropping the call.

Instead, treat this problem like a warning, and do what the warning
says we do: abort at runtime. To do so, we fake up a __builtin_trap()
expression that gets evaluated as part of the argument.

Added:
    cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp   (with props)
Modified:
    cfe/trunk/lib/Sema/SemaExpr.cpp
    cfe/trunk/test/SemaCXX/vararg-non-pod.cpp

Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=131805&r1=131804&r2=131805&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Sat May 21 14:26:31 2011
@@ -449,13 +449,13 @@
   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))
+    DiagRuntimeBehavior(E->getLocStart(), 0,
+                        PDiag(diag::err_cannot_pass_objc_interface_to_vararg)
+                          << E->getType() << CT))
     return ExprError();
-
-  // C++ [expr.call]p7 prohibits non-POD types.
+  
   if (!E->getType()->isPODType()) {
     // C++0x [expr.call]p7:
     //   Passing a potentially-evaluated argument of class type (Clause 9) 
@@ -477,8 +477,28 @@
     } else if (DiagRuntimeBehavior(E->getLocStart(), 0,
                           PDiag(diag::warn_cannot_pass_non_pod_arg_to_vararg)
                             << getLangOptions().CPlusPlus0x << E->getType() 
-                            << CT))
-      return ExprError();
+                            << CT)) {
+      // Turn this into a trap.
+      CXXScopeSpec SS;
+      UnqualifiedId Name;
+      Name.setIdentifier(PP.getIdentifierInfo("__builtin_trap"),
+                         E->getLocStart());
+      ExprResult TrapFn = ActOnIdExpression(TUScope, SS, Name, true, false);
+      if (TrapFn.isInvalid())
+        return ExprError();
+
+      ExprResult Call = ActOnCallExpr(TUScope, TrapFn.get(), E->getLocStart(),
+                                      MultiExprArg(), E->getLocEnd());
+      if (Call.isInvalid())
+        return ExprError();
+      
+      ExprResult Comma = ActOnBinOp(TUScope, E->getLocStart(), tok::comma,
+                                    Call.get(), E);
+      if (Comma.isInvalid())
+        return ExprError();
+      
+      E = Comma.get();
+    }
   }
   
   return Owned(E);

Added: cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp?rev=131805&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp Sat May 21 14:26:31 2011
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -Wno-error=non-pod-varargs -emit-llvm -o - %s | FileCheck %s
+
+struct X {
+  X();
+  X(const X&);
+  ~X();
+};
+
+void vararg(...);
+
+// CHECK: define void @_Z4test1X
+void test(X x) {
+  // CHECK: call void @llvm.trap()
+  vararg(x);
+  // CHECK: ret void
+}

Propchange: cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp
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Propchange: cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp
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    svn:keywords = Id

Propchange: cfe/trunk/test/CodeGenCXX/vararg-non-pod.cpp
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Modified: cfe/trunk/test/SemaCXX/vararg-non-pod.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/vararg-non-pod.cpp?rev=131805&r1=131804&r2=131805&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/vararg-non-pod.cpp (original)
+++ cfe/trunk/test/SemaCXX/vararg-non-pod.cpp Sat May 21 14:26:31 2011
@@ -56,15 +56,18 @@
 }
 
 class E {
-  E(int, ...);
+  E(int, ...); // expected-note 2{{implicitly declared private here}}
 };
 
 void t5()
 {
   C c(10);
   
-  E e(10, c); // expected-warning{{cannot pass object of non-POD type 'C' through variadic constructor; call will abort at runtime}}
-  (void)E(10, c); // expected-warning{{cannot pass object of non-POD type 'C' through variadic constructor; call will abort at runtime}}
+  E e(10, c); // expected-warning{{cannot pass object of non-POD type 'C' through variadic constructor; call will abort at runtime}} \
+    // expected-error{{calling a private constructor of class 'E'}}
+  (void)E(10, c); // expected-warning{{cannot pass object of non-POD type 'C' through variadic constructor; call will abort at runtime}} \
+    // expected-error{{calling a private constructor of class 'E'}}
+
 }
 
 // PR5761: unevaluated operands and the non-POD warning