Format strings: correct signedness if already correcting width (%d,%u).

It is valid to do this:
  printf("%u", (int)x);

But if we see this:
  printf("%lu", (int)x);

...our fixit should suggest %d, not %u.

llvm-svn: 172739

1 files changed, 19 insertions, 1 deletions

diff --git a/clang/lib/Analysis/PrintfFormatString.cpp b/clang/lib/Analysis/PrintfFormatString.cpp
index b52433a0a4e..5d37de362a4 100644
--- a/clang/lib/Analysis/PrintfFormatString.cpp
+++ b/clang/lib/Analysis/PrintfFormatString.cpp
@@ -499,8 +499,26 @@ bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt,
   if (isa<TypedefType>(QT) && (LangOpt.C99 || LangOpt.CPlusPlus11))
     namedTypeToLengthModifier(QT, LM);
 
-  // If fixing the length modifier was enough, we are done.
+  // If fixing the length modifier was enough, we might be done.
   if (hasValidLengthModifier(Ctx.getTargetInfo())) {
+    // If we're going to offer a fix anyway, make sure the sign matches.
+    switch (CS.getKind()) {
+    case ConversionSpecifier::uArg:
+    case ConversionSpecifier::UArg:
+      if (QT->isSignedIntegerType())
+        CS.setKind(clang::analyze_format_string::ConversionSpecifier::dArg);
+      break;
+    case ConversionSpecifier::dArg:
+    case ConversionSpecifier::DArg:
+    case ConversionSpecifier::iArg:
+      if (QT->isUnsignedIntegerType())
+        CS.setKind(clang::analyze_format_string::ConversionSpecifier::uArg);
+      break;
+    default:
+      // Other specifiers do not have signed/unsigned variants.
+      break;
+    }
+
     const analyze_printf::ArgType &ATR = getArgType(Ctx, IsObjCLiteral);
     if (ATR.isValid() && ATR.matchesType(Ctx, QT))
       return true;