[CodeComplete] Add code completion for using alias.

[lh123]

Summary

Add code completion for using alias.

[lh123]

format code.

[kadircet]

mostly LG, apart from the comments around the fallthrough, thanks!

clang/lib/Sema/SemaCodeComplete.cpp

1820

let's take in the CodeCompletionBuilder& too instead of creating a new one.

2060

there's already a fallthrough down below, please drop this one.

2090

let's put this right after using declaration. (this at least needs to be outside this if statement to be triggered by fallthrough)

[lh123]

Address comment.

[kadircet]

LGTM, thanks!

Will land this one too. In the meantime feel free to apply for commit access, as explained in https://llvm.org/docs/DeveloperPolicy.html#obtaining-commit-access (IIRC, you already have a couple patches, if not you can also point at these after I land)

[kadircet]

this seems to be failing to merge, could you rebase on top of head?

[lh123]

Rebase to head.

clang/lib/Sema/SemaCodeComplete.cpp

static void AddTypedefResult(ResultBuilder &Results) {
   Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
   Builder.AddPlaceholderChunk("type");
   Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
   Builder.AddPlaceholderChunk("name");
   Builder.AddChunk(CodeCompletionString::CK_SemiColon);
   Results.AddResult(CodeCompletionResult(Builder.TakeString()));
 }
 
+// using name = type
+static void AddUsingAliasResult(CodeCompletionBuilder &Builder,
+                                ResultBuilder &Results) {
+  Builder.AddTypedTextChunk("using");
+  Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
+  Builder.AddPlaceholderChunk("name");
+  Builder.AddChunk(CodeCompletionString::CK_Equal);
+  Builder.AddPlaceholderChunk("type");
+  Builder.AddChunk(CodeCompletionString::CK_SemiColon);
+  Results.AddResult(CodeCompletionResult(Builder.TakeString()));
+}
+
 static bool WantTypesInContext(Sema::ParserCompletionContext CCC,
                                const LangOptions &LangOpts) {
   switch (CCC) {
   case Sema::PCC_Namespace:
   case Sema::PCC_Class:
   case Sema::PCC_ObjCInstanceVariableList:
   case Sema::PCC_Template:
   case Sema::PCC_MemberTemplate:
if (SemaRef.getLangOpts().CPlusPlus) {
       } else {
         Results.AddResult(Result("template", CodeCompletionResult::RK_Keyword));
       }
     }
 
     if (SemaRef.getLangOpts().ObjC)
       AddObjCTopLevelResults(Results, true);
 
     AddTypedefResult(Results);
     LLVM_FALLTHROUGH;
 
   case Sema::PCC_Class:
     if (SemaRef.getLangOpts().CPlusPlus) {
       // Using declaration
       Builder.AddTypedTextChunk("using");
       Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
       Builder.AddPlaceholderChunk("qualifier");
       Builder.AddTextChunk("::");
       Builder.AddPlaceholderChunk("name");
       Builder.AddChunk(CodeCompletionString::CK_SemiColon);
       Results.AddResult(Result(Builder.TakeString()));
 
+      if (SemaRef.getLangOpts().CPlusPlus11)
+        AddUsingAliasResult(Builder, Results);
+
       // using typename qualifier::name (only in a dependent context)
       if (SemaRef.CurContext->isDependentContext()) {
         Builder.AddTypedTextChunk("using typename");
         Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
         Builder.AddPlaceholderChunk("qualifier");
         Builder.AddTextChunk("::");
         Builder.AddPlaceholderChunk("name");
         Builder.AddChunk(CodeCompletionString::CK_SemiColon);
         Results.AddResult(Result(Builder.TakeString()));
       }
 
       AddStaticAssertResult(Builder, Results, SemaRef.getLangOpts());
 
       if (CCC == Sema::PCC_Class) {
         AddTypedefResult(Results);
 
         bool IsNotInheritanceScope =
             !(S->getFlags() & Scope::ClassInheritanceScope);
         // public:
         Builder.AddTypedTextChunk("public");
         if (IsNotInheritanceScope && Results.includeCodePatterns())
           Builder.AddChunk(CodeCompletionString::CK_Colon);
case Sema::PCC_ObjCImplementation:
     break;
 
   case Sema::PCC_ObjCInstanceVariableList:
     AddObjCVisibilityResults(SemaRef.getLangOpts(), Results, true);
     break;
 
   case Sema::PCC_RecoveryInFunction:
   case Sema::PCC_Statement: {
+    if (SemaRef.getLangOpts().CPlusPlus11)
+      AddUsingAliasResult(Builder, Results);
+
     AddTypedefResult(Results);
 
     if (SemaRef.getLangOpts().CPlusPlus && Results.includeCodePatterns() &&
         SemaRef.getLangOpts().CXXExceptions) {
       Builder.AddTypedTextChunk("try");
       Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
       Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
       Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);

clang/test/CodeCompletion/ordinary-name-cxx11.cpp

void foo() {
   // CHECK-CC1: COMPLETION: TYPEDEF : TYPEDEF
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-CC1-NEXT: COMPLETION: Pattern : [#std::type_info#]typeid(<#expression-or-type#>)
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typename <#name#>
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-CC1-NEXT: COMPLETION: union
   // CHECK-CC1-NEXT: COMPLETION: unsigned
+  // CHECK-CC1-NEXT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-CC1-NEXT: COMPLETION: Pattern : using namespace <#identifier#>;
   // CHECK-CC1-NEXT: COMPLETION: void
   // CHECK-CC1-NEXT: COMPLETION: volatile
   // CHECK-CC1-NEXT: COMPLETION: wchar_t
   // CHECK-CC1-NEXT: COMPLETION: Pattern : while (<#condition#>) {
   // CHECK-CC1-NEXT: <#statements#>
   // CHECK-CC1-NEXT: }
   // CHECK-CC1: COMPLETION: X : X
void foo() {
   // CHECK-CC2-NEXT: COMPLETION: TYPEDEF : TYPEDEF
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typename <#name#>
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-CC2-NEXT: COMPLETION: union
   // CHECK-CC2-NEXT: COMPLETION: unsigned
   // CHECK-CC2-NEXT: COMPLETION: Pattern : using <#qualifier#>::<#name#>;
+  // CHECK-CC2-NEXT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-CC2-NEXT: COMPLETION: Pattern : using namespace <#identifier#>;
   // CHECK-CC2-NEXT: COMPLETION: void
   // CHECK-CC2-NEXT: COMPLETION: volatile
   // CHECK-CC2-NEXT: COMPLETION: wchar_t
   // CHECK-CC2-NEXT: COMPLETION: X : X
 
   // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:1:19 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC3 %s
   // CHECK-CC3: COMPLETION: bool
void foo() {
   // CHECK-CC3-NEXT: COMPLETION: extern
   // CHECK-CC3-NEXT: COMPLETION: float
   // CHECK-CC3-NEXT: COMPLETION: friend
   // CHECK-CC3-NEXT: COMPLETION: inline
   // CHECK-CC3-NEXT: COMPLETION: int
   // CHECK-CC3-NEXT: COMPLETION: long
   // CHECK-CC3-NEXT: COMPLETION: mutable
   // CHECK-CC3-NEXT: COMPLETION: operator
   // CHECK-CC3-NEXT: COMPLETION: Pattern : private: 
   // CHECK-CC3-NEXT: COMPLETION: Pattern : protected: 
   // CHECK-CC3-NEXT: COMPLETION: Pattern : public: 
   // CHECK-CC3-NEXT: COMPLETION: short
   // CHECK-CC3-NEXT: COMPLETION: signed
   // CHECK-CC3-NEXT: COMPLETION: static
   // CHECK-CC3-NEXT: COMPLETION: Pattern : static_assert(<#expression#>, <#message#>);
   // CHECK-CC3-NEXT: COMPLETION: struct
   // CHECK-CC3-NEXT: COMPLETION: Pattern : template<<#parameters#>>
   // CHECK-CC3-NEXT: COMPLETION: thread_local
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typename <#name#>
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-CC3-NEXT: COMPLETION: union
   // CHECK-CC3-NEXT: COMPLETION: unsigned
   // CHECK-CC3-NEXT: COMPLETION: Pattern : using <#qualifier#>::<#name#>
+  // CHECK-CC3-NEXT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-CC3-NEXT: COMPLETION: virtual
   // CHECK-CC3-NEXT: COMPLETION: void
   // CHECK-CC3-NEXT: COMPLETION: volatile
   // CHECK-CC3-NEXT: COMPLETION: wchar_t
   // CHECK-CC3-NEXT: COMPLETION: X : X
 
   // RUN: %clang_cc1 -fsyntax-only -fcxx-exceptions -code-completion-patterns -code-completion-at=%s:6:11 -std=gnu++11 %s -o - | FileCheck -check-prefix=CHECK-CC4 %s
   // CHECK-CC4: COMPLETION: bool
void foo() {
   // CHECK-NO-RTTI: COMPLETION: TYPEDEF : TYPEDEF
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-NO-RTTI-NOT: typeid
   // CHECK-NO-RTTI: COMPLETION: Pattern : typename <#name#>
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-NO-RTTI-NEXT: COMPLETION: union
   // CHECK-NO-RTTI-NEXT: COMPLETION: unsigned
+  // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : using namespace <#identifier#>;
   // CHECK-NO-RTTI-NEXT: COMPLETION: void
   // CHECK-NO-RTTI-NEXT: COMPLETION: volatile
   // CHECK-NO-RTTI-NEXT: COMPLETION: wchar_t
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : while (<#condition#>) {
   // CHECK-NO-RTTI: COMPLETION: X : X
   // CHECK-NO-RTTI-NEXT: COMPLETION: y : [#int#]y
   // CHECK-NO-RTTI-NEXT: COMPLETION: z : [#void#]z(<#int#>)

clang/test/CodeCompletion/ordinary-name.cpp

void foo() {
   // CHECK-CC1: COMPLETION: TYPEDEF : TYPEDEF
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-CC1-NEXT: COMPLETION: Pattern : [#std::type_info#]typeid(<#expression-or-type#>)
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typename <#name#>
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-CC1-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-CC1-NEXT: COMPLETION: union
   // CHECK-CC1-NEXT: COMPLETION: unsigned
+  // CHECK-CC1-NOT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-CC1-NEXT: COMPLETION: Pattern : using namespace <#identifier#>;
   // CHECK-CC1-NEXT: COMPLETION: void
   // CHECK-CC1-NEXT: COMPLETION: volatile
   // CHECK-CC1-NEXT: COMPLETION: wchar_t
   // CHECK-CC1-NEXT: COMPLETION: Pattern : while (<#condition#>) {
   // CHECK-CC1-NEXT: <#statements#>
   // CHECK-CC1-NEXT: }
   // CHECK-CC1: COMPLETION: X : X
void foo() {
   // CHECK-CC2-NEXT: COMPLETION: TYPEDEF : TYPEDEF
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typename <#name#>
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-CC2-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-CC2-NEXT: COMPLETION: union
   // CHECK-CC2-NEXT: COMPLETION: unsigned
   // CHECK-CC2-NEXT: COMPLETION: Pattern : using <#qualifier#>::<#name#>;
+  // CHECK-CC2-NOT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-CC2-NEXT: COMPLETION: Pattern : using namespace <#identifier#>;
   // CHECK-CC2-NEXT: COMPLETION: void
   // CHECK-CC2-NEXT: COMPLETION: volatile
   // CHECK-CC2-NEXT: COMPLETION: wchar_t
   // CHECK-CC2-NEXT: COMPLETION: X : X
 
   // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:1:19 -std=gnu++98 %s -o - | FileCheck -check-prefix=CHECK-CC3 %s
   // CHECK-CC3: COMPLETION: bool
   // CHECK-CC3-NEXT: COMPLETION: char
   // CHECK-CC3-NEXT: COMPLETION: class
   // CHECK-CC3-NEXT: COMPLETION: const
   // CHECK-CC3-NEXT: COMPLETION: double
   // CHECK-CC3-NEXT: COMPLETION: enum
   // CHECK-CC3-NEXT: COMPLETION: explicit
   // CHECK-CC3-NEXT: COMPLETION: extern
   // CHECK-CC3-NEXT: COMPLETION: float
   // CHECK-CC3-NEXT: COMPLETION: friend
   // CHECK-CC3-NEXT: COMPLETION: inline
   // CHECK-CC3-NEXT: COMPLETION: int
   // CHECK-CC3-NEXT: COMPLETION: long
   // CHECK-CC3-NEXT: COMPLETION: mutable
   // CHECK-CC3-NEXT: COMPLETION: operator
   // CHECK-CC3-NEXT: COMPLETION: Pattern : private: 
   // CHECK-CC3-NEXT: COMPLETION: Pattern : protected: 
   // CHECK-CC3-NEXT: COMPLETION: Pattern : public: 
   // CHECK-CC3-NEXT: COMPLETION: short
   // CHECK-CC3-NEXT: COMPLETION: signed
   // CHECK-CC3-NEXT: COMPLETION: static
   // CHECK-CC3-NEXT: COMPLETION: struct
   // CHECK-CC3-NEXT: COMPLETION: Pattern : template<<#parameters#>>
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typename <#name#>
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-CC3-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-CC3-NEXT: COMPLETION: union
   // CHECK-CC3-NEXT: COMPLETION: unsigned
   // CHECK-CC3-NEXT: COMPLETION: Pattern : using <#qualifier#>::<#name#>;
+  // CHECK-CC3-NOT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-CC3-NEXT: COMPLETION: virtual
   // CHECK-CC3-NEXT: COMPLETION: void
   // CHECK-CC3-NEXT: COMPLETION: volatile
   // CHECK-CC3-NEXT: COMPLETION: wchar_t
   // CHECK-CC3-NEXT: COMPLETION: X : X
 
   // RUN: %clang_cc1 -fsyntax-only -fcxx-exceptions -code-completion-patterns -code-completion-at=%s:6:11 -std=gnu++98 %s -o - | FileCheck -check-prefix=CHECK-CC4 %s
   // CHECK-CC4: COMPLETION: bool
void foo() {
   // CHECK-NO-RTTI: COMPLETION: TYPEDEF : TYPEDEF
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : typedef <#type#> <#name#>;
   // CHECK-NO-RTTI-NOT: typeid
   // CHECK-NO-RTTI: COMPLETION: Pattern : typename <#name#>
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : typeof <#expression#>
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : typeof(<#type#>)
   // CHECK-NO-RTTI-NEXT: COMPLETION: union
   // CHECK-NO-RTTI-NEXT: COMPLETION: unsigned
+  // CHECK-NO-RTTI-NOT: COMPLETION: Pattern : using <#name#> = <#type#>;
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : using namespace <#identifier#>;
   // CHECK-NO-RTTI-NEXT: COMPLETION: void
   // CHECK-NO-RTTI-NEXT: COMPLETION: volatile
   // CHECK-NO-RTTI-NEXT: COMPLETION: wchar_t
   // CHECK-NO-RTTI-NEXT: COMPLETION: Pattern : while (<#condition#>) {
   // CHECK-NO-RTTI: COMPLETION: X : X
   // CHECK-NO-RTTI-NEXT: COMPLETION: y : [#int#]y
   // CHECK-NO-RTTI-NEXT: COMPLETION: z : [#void#]z(<#int#>)