Offer typo suggestions for 'using' declarations.

Patch courtesy of Luke Zarko <zarko@google.com>

llvm-svn: 186019

clang/lib/Sema/SemaDeclCXX.cpp

@@ -7024,6 +7024,35 @@ void Sema::HideUsingShadowDecl(Scope *S, UsingShadowDecl *Shadow) {
   // be possible for this to happen, because...?
 }
 
+class UsingValidatorCCC : public CorrectionCandidateCallback {
+public:
+  UsingValidatorCCC(bool IsTypeName, bool IsInstantiation)
+      : IsTypeName(IsTypeName), IsInstantiation(IsInstantiation) {}
+  
+  virtual bool ValidateCandidate(const TypoCorrection &Candidate) {
+    if (NamedDecl *ND = Candidate.getCorrectionDecl()) {
+      if (isa<NamespaceDecl>(ND))
+        return false;
+      // Completely unqualified names are invalid for a 'using' declaration.
+      bool droppedSpecifier = Candidate.WillReplaceSpecifier() &&
+                              !Candidate.getCorrectionSpecifier();
+      if (droppedSpecifier)
+        return false;
+      else if (isa<TypeDecl>(ND))
+        return IsTypeName || !IsInstantiation;
+      else
+        return !IsTypeName;
+    } else {
+      // Keywords are not valid here.
+      return false;
+    }
+  }
+
+private:
+  bool IsTypeName;
+  bool IsInstantiation;
+};
+
 /// Builds a using declaration.
 ///
 /// \param IsInstantiation - Whether this call arises from an
@@ -7133,11 +7162,32 @@ NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
 
   LookupQualifiedName(R, LookupContext);
 
+  // Try to correct typos if possible.
   if (R.empty()) {
-    Diag(IdentLoc, diag::err_no_member) 
-      << NameInfo.getName() << LookupContext << SS.getRange();
-    UD->setInvalidDecl();
-    return UD;
+    UsingValidatorCCC CCC(IsTypeName, IsInstantiation);
+    if (TypoCorrection Corrected = CorrectTypo(R.getLookupNameInfo(),
+                                               R.getLookupKind(), S, &SS, CCC)){
+      // We reject any correction for which ND would be NULL.
+      NamedDecl *ND = Corrected.getCorrectionDecl();
+      std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
+      std::string CorrectedQuotedStr(Corrected.getQuoted(getLangOpts()));
+      R.setLookupName(Corrected.getCorrection());
+      R.addDecl(ND);
+      // We reject candidates where droppedSpecifier == true, hence the
+      // literal '0' below.
+      Diag(R.getNameLoc(), diag::err_no_member_suggest)
+        << NameInfo.getName() << LookupContext << 0
+        << CorrectedQuotedStr << SS.getRange()
+        << FixItHint::CreateReplacement(Corrected.getCorrectionRange(),
+                                        CorrectedStr);
+      Diag(ND->getLocation(), diag::note_previous_decl)
+        << CorrectedQuotedStr;
+    } else {
+      Diag(IdentLoc, diag::err_no_member) 
+        << NameInfo.getName() << LookupContext << SS.getRange();
+      UD->setInvalidDecl();
+      return UD;
+    }
   }
 
   if (R.isAmbiguous()) {

clang/test/FixIt/typo-using.cpp

@@ -0,0 +1,56 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: cp %s %t
+// RUN: not %clang_cc1 -fsyntax-only -fixit -x c++ %t
+// RUN: %clang_cc1 -fsyntax-only -pedantic -Werror -x c++ %t
+// RUN: grep using_suggestion_tyname_ty_dropped_specifier %t
+
+// These tests have been separated from typo.cpp to keep the maximum typo
+// correction counter from ticking over; this causes spurious failures.
+
+namespace using_suggestion_ty {
+namespace N { class AAA {}; } // expected-note {{'AAA' declared here}}
+using N::AAB; // expected-error {{no member named 'AAB' in namespace 'using_suggestion_ty::N'; did you mean 'AAA'?}}
+}
+
+namespace using_suggestion_tyname_ty {
+namespace N { class AAA {}; } // expected-note {{'AAA' declared here}}
+using typename N::AAB; // expected-error {{no member named 'AAB' in namespace 'using_suggestion_tyname_ty::N'; did you mean 'AAA'?}}
+}
+
+namespace using_suggestion_val {
+namespace N { void FFF() {} } // expected-note {{'FFF' declared here}}
+using N::FFG; // expected-error {{no member named 'FFG' in namespace 'using_suggestion_val::N'; did you mean 'FFF'?}}
+}
+
+namespace using_suggestion_ty_dropped_specifier {
+class AAA {}; // expected-note {{'::using_suggestion_ty_dropped_specifier::AAA' declared here}}
+namespace N { }
+using N::AAA; // expected-error {{no member named 'AAA' in namespace 'using_suggestion_ty_dropped_specifier::N'; did you mean '::using_suggestion_ty_dropped_specifier::AAA'?}}
+}
+
+namespace using_suggestion_tyname_ty_dropped_specifier {
+class AAA {}; // expected-note {{'::using_suggestion_tyname_ty_dropped_specifier::AAA' declared here}}
+namespace N { }
+using typename N::AAA; // expected-error {{no member named 'AAA' in namespace 'using_suggestion_tyname_ty_dropped_specifier::N'; did you mean '::using_suggestion_tyname_ty_dropped_specifier::AAA'?}}
+}
+
+namespace using_suggestion_val_dropped_specifier {
+void FFF() {} // expected-note {{'::using_suggestion_val_dropped_specifier::FFF' declared here}}
+namespace N { }
+using N::FFF; // expected-error {{no member named 'FFF' in namespace 'using_suggestion_val_dropped_specifier::N'; did you mean '::using_suggestion_val_dropped_specifier::FFF'?}}
+}
+
+namespace using_suggestion_member_ty {
+class CCC { public: typedef int AAA; }; // expected-note {{'AAA' declared here}}
+class DDD : public CCC { public: using CCC::AAB; }; // expected-error {{no member named 'AAB' in 'using_suggestion_member_ty::CCC'; did you mean 'AAA'?}}
+}
+
+namespace using_suggestion_member_val {
+class CCC { public: void AAA() { } }; // expected-note {{'AAA' declared here}}
+class DDD : public CCC { public: using CCC::AAB; }; // expected-error {{no member named 'AAB' in 'using_suggestion_member_val::CCC'; did you mean 'AAA'?}}
+}
+
+namespace using_suggestion_member_tyname_ty {
+class CCC { public: typedef int AAA; }; // expected-note {{'AAA' declared here}}
+class DDD : public CCC { public: using typename CCC::AAB; }; // expected-error {{no member named 'AAB' in 'using_suggestion_member_tyname_ty::CCC'; did you mean 'AAA'?}}
+}

clang/test/SemaCXX/using-decl-1.cpp

@@ -118,3 +118,45 @@ namespace foo
     using ::foo::Class1::Function; // expected-error{{incomplete type 'foo::Class1' named in nested name specifier}}
   };
 }
+
+// Don't suggest non-typenames for positions requiring typenames.
+namespace using_suggestion_tyname_val {
+namespace N { void FFF() {} }
+using typename N::FFG; // expected-error {{no member named 'FFG' in namespace 'using_suggestion_tyname_val::N'}}
+}
+
+namespace using_suggestion_member_tyname_val {
+class CCC { public: void AAA() { } };
+class DDD : public CCC { public: using typename CCC::AAB; }; // expected-error {{no member named 'AAB' in 'using_suggestion_member_tyname_val::CCC'}}
+}
+
+namespace using_suggestion_tyname_val_dropped_specifier {
+void FFF() {}
+namespace N { }
+using typename N::FFG; // expected-error {{no member named 'FFG' in namespace 'using_suggestion_tyname_val_dropped_specifier::N'}}
+}
+
+// Currently hints aren't provided to drop out the incorrect M::.
+namespace using_suggestion_ty_dropped_nested_specifier {
+namespace N {
+class AAA {};
+namespace M { }
+}
+using N::M::AAA; // expected-error {{no member named 'AAA' in namespace 'using_suggestion_ty_dropped_nested_specifier::N::M'}}
+}
+
+namespace using_suggestion_tyname_ty_dropped_nested_specifier {
+namespace N {
+class AAA {};
+namespace M { }
+}
+using typename N::M::AAA; // expected-error {{no member named 'AAA' in namespace 'using_suggestion_tyname_ty_dropped_nested_specifier::N::M'}}
+}
+
+namespace using_suggestion_val_dropped_nested_specifier {
+namespace N {
+void FFF() {}
+namespace M { }
+}
+using N::M::FFF; // expected-error {{no member named 'FFF' in namespace 'using_suggestion_val_dropped_nested_specifier::N::M'}}
+}