Optionally add code completion results for arrow instead of dot

Currently getting such completions requires source correction, reparsing
and calling completion again. And if it shows no results and rollback is
required then it costs one more reparse.

With this change it's possible to get all results which can be later
filtered to split changes which require correction.

Differential Revision: https://reviews.llvm.org/D41537

llvm-svn: 333272

clang/include/clang/Driver/CC1Options.td

@@ -445,6 +445,8 @@ def no_code_completion_ns_level_decls : Flag<["-"], "no-code-completion-ns-level
   HelpText<"Do not include declarations inside namespaces (incl. global namespace) in the code-completion results.">;
 def code_completion_brief_comments : Flag<["-"], "code-completion-brief-comments">,
   HelpText<"Include brief documentation comments in code-completion results.">;
+def code_completion_with_fixits : Flag<["-"], "code-completion-with-fixits">,
+  HelpText<"Include code completion results which require small fix-its.">;
 def disable_free : Flag<["-"], "disable-free">,
   HelpText<"Disable freeing of memory on exit">;
 def discard_value_names : Flag<["-"], "discard-value-names">,

clang/include/clang/Sema/CodeCompleteConsumer.h

@@ -783,6 +783,33 @@ class CodeCompletionResult {
   /// The availability of this result.
   CXAvailabilityKind Availability = CXAvailability_Available;
 
+  /// FixIts that *must* be applied before inserting the text for the
+  /// corresponding completion item.
+  ///
+  /// Completion items with non-empty fixits will not be returned by default,
+  /// they should be explicitly requested by setting
+  /// CompletionOptions::IncludeFixIts. For the editors to be able to
+  /// compute position of the cursor for the completion item itself, the
+  /// following conditions are guaranteed to hold for RemoveRange of the stored
+  /// fixits:
+  ///  - Ranges in the fixits are guaranteed to never contain the completion
+  ///  point (or identifier under completion point, if any) inside them, except
+  ///  at the start or at the end of the range.
+  ///  - If a fixit range starts or ends with completion point (or starts or
+  ///  ends after the identifier under completion point), it will contain at
+  ///  least one character. It allows to unambiguously recompute completion
+  ///  point after applying the fixit.
+  /// The intuition is that provided fixits change code around the identifier we
+  /// complete, but are not allowed to touch the identifier itself or the
+  /// completion point. One example of completion items with corrections are the
+  /// ones replacing '.' with '->' and vice versa:
+  /// std::unique_ptr<std::vector<int>> vec_ptr;
+  /// In 'vec_ptr.^', one of completion items is 'push_back', it requires
+  /// replacing '.' with '->'.
+  /// In 'vec_ptr->^', one of completion items is 'release', it requires
+  /// replacing '->' with '.'.
+  std::vector<FixItHint> FixIts;
+
   /// Whether this result is hidden by another name.
   bool Hidden : 1;
 
@@ -807,15 +834,17 @@ class CodeCompletionResult {
   NestedNameSpecifier *Qualifier = nullptr;
 
   /// Build a result that refers to a declaration.
-  CodeCompletionResult(const NamedDecl *Declaration,
-                       unsigned Priority,
+  CodeCompletionResult(const NamedDecl *Declaration, unsigned Priority,
                        NestedNameSpecifier *Qualifier = nullptr,
                        bool QualifierIsInformative = false,
-                       bool Accessible = true)
+                       bool Accessible = true,
+                       std::vector<FixItHint> FixIts = std::vector<FixItHint>())
       : Declaration(Declaration), Priority(Priority), Kind(RK_Declaration),
         Hidden(false), QualifierIsInformative(QualifierIsInformative),
         StartsNestedNameSpecifier(false), AllParametersAreInformative(false),
-        DeclaringEntity(false), Qualifier(Qualifier) {
+        DeclaringEntity(false), Qualifier(Qualifier),
+        FixIts(std::move(FixIts)) {
+    //FIXME: Add assert to check FixIts range requirements.
     computeCursorKindAndAvailability(Accessible);
   }
 
@@ -1027,6 +1056,10 @@ class CodeCompleteConsumer {
     return CodeCompleteOpts.IncludeBriefComments;
   }
 
+  /// Whether to include completion items with small fix-its, e.g. change
+  /// '.' to '->' on member access, etc.
+  bool includeFixIts() const { return CodeCompleteOpts.IncludeFixIts; }
+
   /// Hint whether to load data from the external AST in order to provide
   /// full results. If false, declarations from the preamble may be omitted.
   bool loadExternal() const {

clang/include/clang/Sema/CodeCompleteOptions.h

@@ -39,10 +39,14 @@ class CodeCompleteOptions {
   /// If false, namespace-level declarations from the preamble may be omitted.
   unsigned LoadExternal : 1;
 
+  /// Include results after corrections (small fix-its), e.g. change '.' to '->'
+  /// on member access, etc.
+  unsigned IncludeFixIts : 1;
+
   CodeCompleteOptions()
       : IncludeMacros(0), IncludeCodePatterns(0), IncludeGlobals(1),
         IncludeNamespaceLevelDecls(1), IncludeBriefComments(0),
-        LoadExternal(1) {}
+        LoadExternal(1), IncludeFixIts(0) {}
 };
 
 } // namespace clang

clang/include/clang/Sema/Sema.h

@@ -10231,7 +10231,7 @@ class Sema {
   struct CodeCompleteExpressionData;
   void CodeCompleteExpression(Scope *S,
                               const CodeCompleteExpressionData &Data);
-  void CodeCompleteMemberReferenceExpr(Scope *S, Expr *Base,
+  void CodeCompleteMemberReferenceExpr(Scope *S, Expr *Base, Expr *OtherOpBase,
                                        SourceLocation OpLoc, bool IsArrow,
                                        bool IsBaseExprStatement);
   void CodeCompletePostfixExpression(Scope *S, ExprResult LHS);

clang/lib/Frontend/ASTUnit.cpp

@@ -2122,6 +2122,7 @@ void ASTUnit::CodeComplete(
   CodeCompleteOpts.IncludeGlobals = CachedCompletionResults.empty();
   CodeCompleteOpts.IncludeBriefComments = IncludeBriefComments;
   CodeCompleteOpts.LoadExternal = Consumer.loadExternal();
+  CodeCompleteOpts.IncludeFixIts = Consumer.includeFixIts();
 
   assert(IncludeBriefComments == this->IncludeBriefCommentsInCodeCompletion);
 

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1536,6 +1536,8 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
     = !Args.hasArg(OPT_no_code_completion_ns_level_decls);
   Opts.CodeCompleteOpts.IncludeBriefComments
     = Args.hasArg(OPT_code_completion_brief_comments);
+  Opts.CodeCompleteOpts.IncludeFixIts
+    = Args.hasArg(OPT_code_completion_with_fixits);
 
   Opts.OverrideRecordLayoutsFile
     = Args.getLastArgValue(OPT_foverride_record_layout_EQ);

clang/lib/Parse/ParseExpr.cpp

@@ -1703,8 +1703,10 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
       CXXScopeSpec SS;
       ParsedType ObjectType;
       bool MayBePseudoDestructor = false;
+      Expr* OrigLHS = !LHS.isInvalid() ? LHS.get() : nullptr;
+
       if (getLangOpts().CPlusPlus && !LHS.isInvalid()) {
-        Expr *Base = LHS.get();
+        Expr *Base = OrigLHS;
         const Type* BaseType = Base->getType().getTypePtrOrNull();
         if (BaseType && Tok.is(tok::l_paren) &&
             (BaseType->isFunctionType() ||
@@ -1729,11 +1731,25 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
       }
 
       if (Tok.is(tok::code_completion)) {
+        tok::TokenKind CorrectedOpKind =
+            OpKind == tok::arrow ? tok::period : tok::arrow;
+        ExprResult CorrectedLHS(/*IsInvalid=*/true);
+        if (getLangOpts().CPlusPlus && OrigLHS) {
+          const bool DiagsAreSuppressed = Diags.getSuppressAllDiagnostics();
+          Diags.setSuppressAllDiagnostics(true);
+          CorrectedLHS = Actions.ActOnStartCXXMemberReference(
+              getCurScope(), OrigLHS, OpLoc, CorrectedOpKind, ObjectType,
+              MayBePseudoDestructor);
+          Diags.setSuppressAllDiagnostics(DiagsAreSuppressed);
+        }
+
+        Expr *Base = LHS.get();
+        Expr *CorrectedBase = CorrectedLHS.get();
+
         // Code completion for a member access expression.
-        if (Expr *Base = LHS.get())
-          Actions.CodeCompleteMemberReferenceExpr(
-              getCurScope(), Base, OpLoc, OpKind == tok::arrow,
-              ExprStatementTokLoc == Base->getLocStart());
+        Actions.CodeCompleteMemberReferenceExpr(
+            getCurScope(), Base, CorrectedBase, OpLoc, OpKind == tok::arrow,
+            Base && ExprStatementTokLoc == Base->getLocStart());
 
         cutOffParsing();
         return ExprError();

clang/lib/Sema/CodeCompleteConsumer.cpp

@@ -554,6 +554,24 @@ PrintingCodeCompleteConsumer::ProcessCodeCompleteResults(Sema &SemaRef,
         if (const char *BriefComment = CCS->getBriefComment())
           OS << " : " << BriefComment;
       }
+      for (const FixItHint &FixIt : Results[I].FixIts) {
+        const SourceLocation BLoc = FixIt.RemoveRange.getBegin();
+        const SourceLocation ELoc = FixIt.RemoveRange.getEnd();
+
+        SourceManager &SM = SemaRef.SourceMgr;
+        std::pair<FileID, unsigned> BInfo = SM.getDecomposedLoc(BLoc);
+        std::pair<FileID, unsigned> EInfo = SM.getDecomposedLoc(ELoc);
+        // Adjust for token ranges.
+        if (FixIt.RemoveRange.isTokenRange())
+          EInfo.second += Lexer::MeasureTokenLength(ELoc, SM, SemaRef.LangOpts);
+
+        OS << " (requires fix-it:"
+           << " {" << SM.getLineNumber(BInfo.first, BInfo.second) << ':'
+           << SM.getColumnNumber(BInfo.first, BInfo.second) << '-'
+           << SM.getLineNumber(EInfo.first, EInfo.second) << ':'
+           << SM.getColumnNumber(EInfo.first, EInfo.second) << "}"
+           << " to \"" << FixIt.CodeToInsert << "\")";
+      }
       OS << '\n';
       break;