Format string checking: selectively ignore implicit casts to 'int'

when checking if the format specifier matches the type of the data
argument and the length modifier indicates the data type is 'char' or
'short'.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94992 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 6 deletions

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 4e2e9c7376..5db7038405 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1280,14 +1280,25 @@ CheckPrintfHandler::HandleFormatSpecifier(const analyze_printf::FormatSpecifier
   // format specifier.
   const Expr *Ex = getDataArg(NumConversions);
   const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context);
-    
+  
   if (const QualType *T = ATR.getSpecificType()) {
     if (!MatchType(*T, Ex->getType(), true)) {
-      S.Diag(getLocationOfByte(CS.getStart()),
-             diag::warn_printf_conversion_argument_type_mismatch)
-        << *T << Ex->getType()
-        << getFormatSpecifierRange(startSpecifier, specifierLen)
-        << Ex->getSourceRange();
+      // Check if we didn't match because of an implicit cast from a 'char'
+      // or 'short' to an 'int'.  This is done because printf is a varargs
+      // function.
+      bool hasError = true;      
+      if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex))
+        if (ICE->getType() == S.Context.IntTy) {
+          Ex = ICE->getSubExpr();
+          hasError = !MatchType(*T, Ex->getType(), true);
+        }
+      
+      if (hasError)            
+        S.Diag(getLocationOfByte(CS.getStart()),
+               diag::warn_printf_conversion_argument_type_mismatch)
+          << *T << Ex->getType()
+          << getFormatSpecifierRange(startSpecifier, specifierLen)
+          << Ex->getSourceRange();
     }
     return true;
   }