Warn about non-standard format strings (pr12017)

This adds the -Wformat-non-standard flag (off by default,
enabled by -pedantic), which warns about non-standard
things in format strings (such as the 'q' length modifier,
the 'S' conversion specifier, etc.)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151154 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 131 insertions, 2 deletions

diff --git a/lib/Analysis/FormatString.cpp b/lib/Analysis/FormatString.cpp
index fcc293bf30..5785655c94 100644
--- a/lib/Analysis/FormatString.cpp
+++ b/lib/Analysis/FormatString.cpp
@@ -602,3 +602,74 @@ bool FormatSpecifier::hasValidLengthModifier() const {
   }
   llvm_unreachable("Invalid LengthModifier Kind!");
 }
+
+bool FormatSpecifier::hasStandardLengthModifier() const {
+  switch (LM.getKind()) {
+    case LengthModifier::None:
+    case LengthModifier::AsChar:
+    case LengthModifier::AsShort:
+    case LengthModifier::AsLong:
+    case LengthModifier::AsLongLong:
+    case LengthModifier::AsIntMax:
+    case LengthModifier::AsSizeT:
+    case LengthModifier::AsPtrDiff:
+    case LengthModifier::AsLongDouble:
+      return true;
+    case LengthModifier::AsAllocate:
+    case LengthModifier::AsMAllocate:
+    case LengthModifier::AsQuad:
+      return false;
+  }
+  llvm_unreachable("Invalid LengthModifier Kind!");
+}
+
+bool FormatSpecifier::hasStandardConversionSpecifier(const LangOptions &LangOpt) const {
+  switch (CS.getKind()) {
+    case ConversionSpecifier::cArg:
+    case ConversionSpecifier::dArg:
+    case ConversionSpecifier::iArg:
+    case ConversionSpecifier::oArg:
+    case ConversionSpecifier::uArg:
+    case ConversionSpecifier::xArg:
+    case ConversionSpecifier::XArg:
+    case ConversionSpecifier::fArg:
+    case ConversionSpecifier::FArg:
+    case ConversionSpecifier::eArg:
+    case ConversionSpecifier::EArg:
+    case ConversionSpecifier::gArg:
+    case ConversionSpecifier::GArg:
+    case ConversionSpecifier::aArg:
+    case ConversionSpecifier::AArg:
+    case ConversionSpecifier::sArg:
+    case ConversionSpecifier::pArg:
+    case ConversionSpecifier::nArg:
+    case ConversionSpecifier::ObjCObjArg:
+    case ConversionSpecifier::ScanListArg:
+    case ConversionSpecifier::PercentArg:
+      return true;
+    case ConversionSpecifier::CArg:
+    case ConversionSpecifier::SArg:
+      return LangOpt.ObjC1 || LangOpt.ObjC2;
+    case ConversionSpecifier::InvalidSpecifier:
+    case ConversionSpecifier::PrintErrno:
+      return false;
+  }
+  llvm_unreachable("Invalid ConversionSpecifier Kind!");
+}
+
+bool FormatSpecifier::hasStandardLengthConversionCombination() const {
+  if (LM.getKind() == LengthModifier::AsLongDouble) {
+    switch(CS.getKind()) {
+        case ConversionSpecifier::dArg:
+        case ConversionSpecifier::iArg:
+        case ConversionSpecifier::oArg:
+        case ConversionSpecifier::uArg:
+        case ConversionSpecifier::xArg:
+        case ConversionSpecifier::XArg:
+          return false;
+        default:
+          return true;
+    }
+  }
+  return true;
+}
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 7f42b2059d..a89e813cc8 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1663,7 +1663,20 @@ public:
 
   void HandleIncompleteSpecifier(const char *startSpecifier,
                                  unsigned specifierLen);
-    
+
+  void HandleNonStandardLengthModifier(
+      const analyze_format_string::LengthModifier &LM,
+      const char *startSpecifier, unsigned specifierLen);
+
+  void HandleNonStandardConversionSpecifier(
+      const analyze_format_string::ConversionSpecifier &CS,
+      const char *startSpecifier, unsigned specifierLen);
+
+  void HandleNonStandardConversionSpecification(
+      const analyze_format_string::LengthModifier &LM,
+      const analyze_format_string::ConversionSpecifier &CS,
+      const char *startSpecifier, unsigned specifierLen);
+
   virtual void HandleInvalidPosition(const char *startSpecifier,
                                      unsigned specifierLen,
                                      analyze_format_string::PositionContext p);
@@ -1739,6 +1752,37 @@ void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
                        getSpecifierRange(startSpecifier, specifierLen));
 }
 
+void CheckFormatHandler::HandleNonStandardLengthModifier(
+    const analyze_format_string::LengthModifier &LM,
+    const char *startSpecifier, unsigned specifierLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << LM.toString()
+                       << "length modifier",
+                       getLocationOfByte(LM.getStart()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen));
+}
+
+void CheckFormatHandler::HandleNonStandardConversionSpecifier(
+    const analyze_format_string::ConversionSpecifier &CS,
+    const char *startSpecifier, unsigned specifierLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << CS.toString()
+                       << "conversion specifier",
+                       getLocationOfByte(CS.getStart()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen));
+}
+
+void CheckFormatHandler::HandleNonStandardConversionSpecification(
+    const analyze_format_string::LengthModifier &LM,
+    const analyze_format_string::ConversionSpecifier &CS,
+    const char *startSpecifier, unsigned specifierLen) {
+  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_conversion_spec)
+                       << LM.toString() << CS.toString(),
+                       getLocationOfByte(LM.getStart()),
+                       /*IsStringLocation*/true,
+                       getSpecifierRange(startSpecifier, specifierLen));
+}
+
 void
 CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
                                      analyze_format_string::PositionContext p) {
@@ -2157,6 +2201,13 @@ CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
                          FixItHint::CreateRemoval(
                            getSpecifierRange(LM.getStart(),
                                              LM.getLength())));
+  if (!FS.hasStandardLengthModifier())
+    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
+  if (!FS.hasStandardConversionSpecifier(S.getLangOptions()))
+    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
+  if (!FS.hasStandardLengthConversionCombination())
+    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
+                                             specifierLen);
 
   // Are we using '%n'?
   if (CS.getKind() == ConversionSpecifier::nArg) {
@@ -2343,6 +2394,14 @@ bool CheckScanfHandler::HandleScanfSpecifier(
                          FixItHint::CreateRemoval(R));
   }
 
+  if (!FS.hasStandardLengthModifier())
+    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
+  if (!FS.hasStandardConversionSpecifier(S.getLangOptions()))
+    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
+  if (!FS.hasStandardLengthConversionCombination())
+    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
+                                             specifierLen);
+
   // The remaining checks depend on the data arguments.
   if (HasVAListArg)
     return true;
@@ -4971,4 +5030,3 @@ void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
     Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
   }
 }
-