commit 2868a736f88e50063264c41e3cd87c927c0c7ab8
author Richard Smith <richard-llvm@metafoo.co.uk> Fri Feb 28 01:36:39 2014 +0000
committer Richard Smith <richard-llvm@metafoo.co.uk> Fri Feb 28 01:36:39 2014 +0000
tree 4c36b9148d5a8788780c04d2828adf4bbc872d66
parent 854d6d0a586b1c328deebf65657ba925af039aed

Add a -Wclass-varargs to warn on objects of any class type being passed through an ellipsis. Since C++11 relaxed the rules on this, we allow a lot more bad code through silently, such as:

  const char *format = "%s";
  std::experimental::string_view view = "foo";
  printf(format, view);

In this case, not only warn about a class type being used here, but also suggest that calling c_str() might be a good idea.

llvm-svn: 202461

clang/lib/Sema/SemaChecking.cpp

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index e9e9742..5229274 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -2765,7 +2765,7 @@
                          const analyze_printf::OptionalFlag &flag,
                          const char *startSpecifier, unsigned specifierLen);
   bool checkForCStrMembers(const analyze_printf::ArgType &AT,
-                           const Expr *E, const CharSourceRange &CSR);
+                           const Expr *E);
 
 };  
 }
@@ -2899,11 +2899,12 @@
   if (!RT)
     return Results;
   const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
-  if (!RD)
+  if (!RD || !RD->getDefinition())
     return Results;
 
   LookupResult R(S, &S.PP.getIdentifierTable().get(Name), SourceLocation(),
                  Sema::LookupMemberName);
+  R.suppressDiagnostics();
 
   // We just need to include all members of the right kind turned up by the
   // filter, at this point.
@@ -2916,12 +2917,26 @@
   return Results;
 }
 
+/// Check if we could call '.c_str()' on an object.
+///
+/// FIXME: This returns the wrong results in some cases (if cv-qualifiers don't
+/// allow the call, or if it would be ambiguous).
+bool Sema::hasCStrMethod(const Expr *E) {
+  typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
+  MethodSet Results =
+      CXXRecordMembersNamed<CXXMethodDecl>("c_str", *this, E->getType());
+  for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
+       MI != ME; ++MI)
+    if ((*MI)->getMinRequiredArguments() == 0)
+      return true;
+  return false;
+}
+
 // Check if a (w)string was passed when a (w)char* was needed, and offer a
 // better diagnostic if so. AT is assumed to be valid.
 // Returns true when a c_str() conversion method is found.
 bool CheckPrintfHandler::checkForCStrMembers(
-    const analyze_printf::ArgType &AT, const Expr *E,
-    const CharSourceRange &CSR) {
+    const analyze_printf::ArgType &AT, const Expr *E) {
   typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
 
   MethodSet Results =
@@ -2930,7 +2945,7 @@
   for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
        MI != ME; ++MI) {
     const CXXMethodDecl *Method = *MI;
-    if (Method->getNumParams() == 0 &&
+    if (Method->getMinRequiredArguments() == 0 &&
         AT.matchesType(S.Context, Method->getReturnType())) {
       // FIXME: Suggest parens if the expression needs them.
       SourceLocation EndLoc =
@@ -3317,7 +3332,7 @@
           << CSR
           << E->getSourceRange(),
         E->getLocStart(), /*IsStringLocation*/false, CSR);
-      checkForCStrMembers(AT, E, CSR);
+      checkForCStrMembers(AT, E);
       break;
 
     case Sema::VAK_Invalid: