[PATCH] D48734: [Sema] Consider all format_arg attributes.

[Michael Kruse via Phabricator via cfe-commits]

Meinersbur created this revision.
Meinersbur added reviewers: dlj, rsmith, Jean-Daniel.

If a function has multiple format_arg attributes, clang only considers the first it finds (because AttributeLists are in reverse order, it is textual last) and ignores all others.

Loop over all FormatArgAttr to print warnings for all declared format_arg attributes.

For instance, GNU gettext's ngettext (select plural or singular version of format string) has two __format_arg__ attributes.


Repository:
  rC Clang

https://reviews.llvm.org/D48734

Files:
  lib/Sema/SemaChecking.cpp
  test/Sema/attr-format_arg.c


Index: test/Sema/attr-format_arg.c
===================================================================
--- test/Sema/attr-format_arg.c
+++ test/Sema/attr-format_arg.c
@@ -4,10 +4,15 @@
 
 const char* f(const char *s) __attribute__((format_arg(1)));
 
+const char *h(const char *msg1, const char *msg2)
+    __attribute__((__format_arg__(1))) __attribute__((__format_arg__(2)));
+
 void g(const char *s) {
   printf("%d", 123);
   printf("%d %d", 123); // expected-warning{{more '%' conversions than data arguments}}
 
   printf(f("%d"), 123);
   printf(f("%d %d"), 123); // expected-warning{{more '%' conversions than data arguments}}
+
+  printf(h("", ""), 123); // expected-warning 2{{format string is empty}}
 }
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -5518,13 +5518,22 @@
   case Stmt::CXXMemberCallExprClass: {
     const CallExpr *CE = cast<CallExpr>(E);
     if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
-      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
+      bool IsFirst = true;
+      StringLiteralCheckType CommonResult;
+      for (const FormatArgAttr *FA : ND->specific_attrs<FormatArgAttr>()) {
         const Expr *Arg = CE->getArg(FA->getFormatIdx().getASTIndex());
-        return checkFormatStringExpr(S, Arg, Args,
-                                     HasVAListArg, format_idx, firstDataArg,
-                                     Type, CallType, InFunctionCall,
-                                     CheckedVarArgs, UncoveredArg, Offset);
-      } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
+        StringLiteralCheckType Result = checkFormatStringExpr(
+            S, Arg, Args, HasVAListArg, format_idx, firstDataArg, Type,
+            CallType, InFunctionCall, CheckedVarArgs, UncoveredArg, Offset);
+        if (IsFirst) {
+          CommonResult = Result;
+          IsFirst = false;
+        }
+      }
+      if (!IsFirst)
+        return CommonResult;
+
+      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
         unsigned BuiltinID = FD->getBuiltinID();
         if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
             BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {


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