[cfe-commits] r97430 - in /cfe/trunk: lib/Sema/SemaStmt.cpp test/Sema/switch.c

[Douglas Gregor]

Author: dgregor
Date: Sun Feb 28 19:04:55 2010
New Revision: 97430

URL: http://llvm.org/viewvc/llvm-project?rev=97430&view=rev
Log:
Don't warn about case-value conversions from a negative value to a
larger unsigned value, since this is implementation-defined
behavior. (We previously suppressed this warning when converting from
a signed value to an unsigned value of the same size).

Modified:
    cfe/trunk/lib/Sema/SemaStmt.cpp
    cfe/trunk/test/Sema/switch.c

Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=97430&r1=97429&r2=97430&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
+++ cfe/trunk/lib/Sema/SemaStmt.cpp Sun Feb 28 19:04:55 2010
@@ -314,15 +314,13 @@
   // Perform a conversion to the promoted condition type if needed.
   if (NewWidth > Val.getBitWidth()) {
     // If this is an extension, just do it.
-    llvm::APSInt OldVal(Val);
     Val.extend(NewWidth);
-
-    // If the input was signed and negative and the output is unsigned,
-    // warn.
-    if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
-      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
-
     Val.setIsSigned(NewSign);
+
+    // If the input was signed and negative and the output is
+    // unsigned, don't bother to warn: this is implementation-defined
+    // behavior.
+    // FIXME: Introduce a second, default-ignored warning for this case?
   } else if (NewWidth < Val.getBitWidth()) {
     // If this is a truncation, check for overflow.
     llvm::APSInt ConvVal(Val);

Modified: cfe/trunk/test/Sema/switch.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/switch.c?rev=97430&r1=97429&r2=97430&view=diff
==============================================================================
--- cfe/trunk/test/Sema/switch.c (original)
+++ cfe/trunk/test/Sema/switch.c Sun Feb 28 19:04:55 2010
@@ -254,3 +254,10 @@
   }
   return 0;
 }
+
+void f1(unsigned x) {
+  switch (x) {
+  case -1: break;
+  default: break;
+  }
+}