Improve 0-argument -Wvexing-parse diagnostic by adding notes with fix-its:

 - If the declarator is at the start of a line, and the previous line contained
   another declarator and ended with a comma, then that comma was probably a
   typo for a semicolon:

   int n = 0, m = 1, l = 2, // k = 5;
   myImportantFunctionCall(); // oops!

 - If removing the parentheses would correctly initialize the object, then
   produce a note suggesting that fix.

 - Otherwise, if there is a simple initializer we can suggest which performs
   value-initialization, then provide a note suggesting a correction to that
   initializer.

Sema::Declarator now tracks the location of the comma prior to the declarator in
the declaration, if there is one, to facilitate providing the note. The code to
determine an appropriate initializer from the -Wuninitialized warning has been
factored out to allow use in both that and -Wvexing-parse.

llvm-svn: 148072

1 files changed, 28 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaFixItUtils.cpp b/clang/lib/Sema/SemaFixItUtils.cpp
index 8e8a46da73e..1f17a9e83e7 100644
--- a/clang/lib/Sema/SemaFixItUtils.cpp
+++ b/clang/lib/Sema/SemaFixItUtils.cpp
@@ -158,3 +158,31 @@ bool ConversionFixItGenerator::tryToFixConversion(const Expr *FullExpr,
 
   return false;
 }
+
+const char *Sema::getFixItZeroInitializerForType(QualType T) const {
+  // Suggest 'nil' if it's defined and appropriate.
+  if ((T->isObjCObjectPointerType() || T->isBlockPointerType()) &&
+      PP.getMacroInfo(&getASTContext().Idents.get("nil")))
+    return " = nil";
+  if (T->isRealFloatingType())
+    return " = 0.0";
+  if (T->isBooleanType() && LangOpts.CPlusPlus)
+    return " = false";
+  if (T->isPointerType() || T->isMemberPointerType()) {
+    if (LangOpts.CPlusPlus0x)
+      return " = nullptr";
+    // Check if 'NULL' is defined.
+    else if (PP.getMacroInfo(&getASTContext().Idents.get("NULL")))
+      return " = NULL";
+  }
+  if (T->isEnumeralType())
+    return 0;
+  if (T->isScalarType())
+    return " = 0";
+  const CXXRecordDecl *RD = T->getAsCXXRecordDecl();
+  if (LangOpts.CPlusPlus0x && RD && !RD->hasUserProvidedDefaultConstructor())
+    return "{}";
+  if (T->isAggregateType())
+    return " = {}";
+  return 0;
+}