Objective-C: Provide fixit with suggested spelling correction
for -Wundeclared-selector warnings. // rdar://14039037



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@183331 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index f1ce4bc..b2387d3 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -2272,6 +2272,57 @@
 }
 
 static void
+HelperSelectorsForTypoCorrection(
+                      SmallVectorImpl<const ObjCMethodDecl *> &BestMethod,
+                      StringRef Typo, const ObjCMethodDecl * Method) {
+  const unsigned MaxEditDistance = 1;
+  unsigned BestEditDistance = MaxEditDistance + 1;
+  StringRef MethodName = Method->getSelector().getAsString();
+  
+  unsigned MinPossibleEditDistance = abs((int)MethodName.size() - (int)Typo.size());
+  if (MinPossibleEditDistance > 0 &&
+      Typo.size() / MinPossibleEditDistance < 1)
+    return;
+  unsigned EditDistance = Typo.edit_distance(MethodName, true, MaxEditDistance);
+  if (EditDistance > MaxEditDistance)
+    return;
+  if (EditDistance == BestEditDistance)
+    BestMethod.push_back(Method);
+  else if (EditDistance < BestEditDistance) {
+    BestMethod.clear();
+    BestMethod.push_back(Method);
+    BestEditDistance = EditDistance;
+  }
+}
+
+const ObjCMethodDecl *
+Sema::SelectorsForTypoCorrection(Selector Sel) {
+  unsigned NumArgs = Sel.getNumArgs();
+  SmallVector<const ObjCMethodDecl *, 8> Methods;
+  
+  for (GlobalMethodPool::iterator b = MethodPool.begin(),
+       e = MethodPool.end(); b != e; b++) {
+    // instance methods
+    for (ObjCMethodList *M = &b->second.first; M; M=M->getNext())
+      if (M->Method &&
+          (M->Method->getSelector().getNumArgs() == NumArgs))
+        Methods.push_back(M->Method);
+    // class methods
+    for (ObjCMethodList *M = &b->second.second; M; M=M->getNext())
+      if (M->Method &&
+          (M->Method->getSelector().getNumArgs() == NumArgs))
+        Methods.push_back(M->Method);
+  }
+  
+  SmallVector<const ObjCMethodDecl *, 8> SelectedMethods;
+  for (unsigned i = 0, e = Methods.size(); i < e; i++) {
+    HelperSelectorsForTypoCorrection(SelectedMethods,
+                                     Sel.getAsString(), Methods[i]);
+  }
+  return (SelectedMethods.size() == 1) ? SelectedMethods[0] : NULL;
+}
+
+static void
 HelperToDiagnoseMismatchedMethodsInGlobalPool(Sema &S,
                                               ObjCMethodList &MethList) {
   ObjCMethodList *M = &MethList;
diff --git a/lib/Sema/SemaExprObjC.cpp b/lib/Sema/SemaExprObjC.cpp
index 23116d8..3b84ace 100644
--- a/lib/Sema/SemaExprObjC.cpp
+++ b/lib/Sema/SemaExprObjC.cpp
@@ -968,8 +968,18 @@
   if (!Method)
     Method = LookupFactoryMethodInGlobalPool(Sel,
                                           SourceRange(LParenLoc, RParenLoc));
-  if (!Method)
-    Diag(SelLoc, diag::warn_undeclared_selector) << Sel;
+  if (!Method) {
+    if (const ObjCMethodDecl *OM = SelectorsForTypoCorrection(Sel)) {
+      Selector MatchedSel = OM->getSelector();
+      SourceRange SelectorRange(LParenLoc.getLocWithOffset(1),
+                                RParenLoc.getLocWithOffset(-1));
+      Diag(SelLoc, diag::warn_undeclared_selector_with_typo)
+        << Sel << MatchedSel
+        << FixItHint::CreateReplacement(SelectorRange, MatchedSel.getAsString());
+      
+    } else
+        Diag(SelLoc, diag::warn_undeclared_selector) << Sel;
+  }
   
   if (!Method ||
       Method->getImplementationControl() != ObjCMethodDecl::Optional) {