r246359 - [AST] Don't crash when comparing incomplete object

[David Majnemer via cfe-commits]

Author: majnemer
Date: Sat Aug 29 03:32:55 2015
New Revision: 246359

URL: http://llvm.org/viewvc/llvm-project?rev=246359&view=rev
Log:
[AST] Don't crash when comparing incomplete object

We cannot tell if an object is past-the-end if its type is incomplete.
Zero sized objects satisfy past-the-end criteria and our object might
turn out to be such an object.

This fixes PR24622.

Modified:
    cfe/trunk/lib/AST/ExprConstant.cpp
    cfe/trunk/test/Sema/const-eval.c

Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=246359&r1=246358&r2=246359&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Sat Aug 29 03:32:55 2015
@@ -6602,9 +6602,15 @@ static bool isOnePastTheEndOfCompleteObj
       !LV.getLValueDesignator().isOnePastTheEnd())
     return false;
 
+  // A pointer to an incomplete type might be past-the-end if the type's size is
+  // zero.  We cannot tell because the type is incomplete.
+  QualType Ty = getType(LV.getLValueBase());
+  if (Ty->isIncompleteType())
+    return true;
+
   // We're a past-the-end pointer if we point to the byte after the object,
   // no matter what our type or path is.
-  auto Size = Ctx.getTypeSizeInChars(getType(LV.getLValueBase()));
+  auto Size = Ctx.getTypeSizeInChars(Ty);
   return LV.getLValueOffset() == Size;
 }
 

Modified: cfe/trunk/test/Sema/const-eval.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/const-eval.c?rev=246359&r1=246358&r2=246359&view=diff
==============================================================================
--- cfe/trunk/test/Sema/const-eval.c (original)
+++ cfe/trunk/test/Sema/const-eval.c Sat Aug 29 03:32:55 2015
@@ -133,3 +133,7 @@ EVAL_EXPR(51, 0 != (float)1e99)
 
 // PR21945
 void PR21945() { int i = (({}), 0l); }
+
+void PR24622();
+struct PR24622 {} pr24622;
+EVAL_EXPR(52, &pr24622 == (void *)&PR24622); // expected-error {{must have a constant size}}