Make -Wformat fix-its preserve original conversion specifiers.

This commit makes PrintfSpecifier::fixType() and ScanfSpecifier::fixType()
only fix a conversion specification enough that Clang wouldn't warn about it,
as opposed to always changing it to use the "canonical" conversion specifier.
(PR11975)

This preserves the user's choice of conversion specifier in cases like:

printf("%a", (long double)1);
where we previously suggested "%Lf", we now suggest "%La"

printf("%x", (long)1);
where we previously suggested "%ld", we now suggest "%lx".

llvm-svn: 150578

1 files changed, 8 insertions, 4 deletions

diff --git a/clang/lib/Analysis/PrintfFormatString.cpp b/clang/lib/Analysis/PrintfFormatString.cpp
index 6da37fc44ab..ff0174e3c3e 100644
--- a/clang/lib/Analysis/PrintfFormatString.cpp
+++ b/clang/lib/Analysis/PrintfFormatString.cpp
@@ -336,7 +336,8 @@ ArgTypeResult PrintfSpecifier::getArgType(ASTContext &Ctx,
   return ArgTypeResult();
 }
 
-bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt) {
+bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt,
+                              ASTContext &Ctx, bool IsObjCLiteral) {
   // Handle strings first (char *, wchar_t *)
   if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) {
     CS.setKind(ConversionSpecifier::sArg);
@@ -432,6 +433,11 @@ bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt) {
     }
   }
 
+  // If fixing the length modifier was enough, we are done.
+  const analyze_printf::ArgTypeResult &ATR = getArgType(Ctx, IsObjCLiteral);
+  if (hasValidLengthModifier() && ATR.isValid() && ATR.matchesType(Ctx, QT))
+    return true;
+
   // Set conversion specifier and disable any flags which do not apply to it.
   // Let typedefs to char fall through to int, as %c is silly for uint8_t.
   if (isa<TypedefType>(QT) && QT->isAnyCharacterType()) {
@@ -451,9 +457,7 @@ bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt) {
     HasAlternativeForm = 0;
   }
   else if (QT->isUnsignedIntegerType()) {
-    // Preserve the original formatting, e.g. 'X', 'o'.
-    if (!cast<PrintfConversionSpecifier>(CS).isUIntArg())
-      CS.setKind(ConversionSpecifier::uArg);
+    CS.setKind(ConversionSpecifier::uArg);
     HasAlternativeForm = 0;
     HasPlusPrefix = 0;
   } else {