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

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 4e2e9c7376b6830fcd96edad72116f1284d9c1a4..5db7038405c3f52a1d8629ffa4ec3269db9febe4 100644 (file)
--- 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;
   }

diff --git a/test/Sema/format-strings.c b/test/Sema/format-strings.c
index 02e39a426be23f26ff3b6f66dcc0fa1a6e8bc2c5..a055bfe1822ba7b3495af2ad3545a355b3b50f3a 100644 (file)
--- a/test/Sema/format-strings.c
+++ b/test/Sema/format-strings.c
@@ -162,6 +162,11 @@ void test10(int x, float f, int i, long long lli) {
   printf("%.", x);  // expected-warning{{incomplete format specifier}}
   printf("%f", 4); // expected-warning{{conversion specifies type 'double' but the argument has type 'int'}}
   printf("%qd", lli);
+  printf("hhX %hhX", (unsigned char)10); // no-warning
+  printf("llX %llX", (long long) 10); // no-warning
+  // This is fine, because there is an implicit conversion to an int.
+  printf("%d", (unsigned char) 10); // no-warning
+  printf("%d", (long long) 10); // expected-warning{{conversion specifies type 'int' but the argument has type 'long long'}}
 } 
 
 typedef struct __aslclient *aslclient;