[backported/clang-7] Optionally add code completion results for arrow instead of dot

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* https://reviews.llvm.org/D41537
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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.

Change-Id: Id2fc3f0518fd53f2a6d0097da3ee723ddeb372ab
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

4 files changed, 46 insertions, 6 deletions

diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 7dea88b62c..86dc2e4c12 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -447,6 +447,8 @@ 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">,
diff --git a/include/clang/Sema/CodeCompleteConsumer.h b/include/clang/Sema/CodeCompleteConsumer.h
index 5d280b5608..720a150f51 100644
--- a/include/clang/Sema/CodeCompleteConsumer.h
+++ b/include/clang/Sema/CodeCompleteConsumer.h
@@ -680,6 +680,33 @@ public:
   /// \brief The availability of this result.
   CXAvailabilityKind Availability;
 
+  /// \brief 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;
+
   /// \brief Whether this result is hidden by another name.
   bool Hidden : 1;
 
@@ -704,17 +731,19 @@ public:
   NestedNameSpecifier *Qualifier;
 
   /// \brief 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),
       StartParameter(0), Kind(RK_Declaration),
       Availability(CXAvailability_Available), 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);
   }
 
@@ -934,6 +963,10 @@ public:
     return CodeCompleteOpts.IncludeBriefComments;
   }
 
+  /// \brief Whether to include completion items with small fix-its, e.g. change
+  /// '.' to '->' on member access, etc.
+  bool includeFixIts() const { return CodeCompleteOpts.IncludeFixIts; }
+
   /// \brief Determine whether the output of this consumer is binary.
   bool isOutputBinary() const { return OutputIsBinary; }
 
diff --git a/include/clang/Sema/CodeCompleteOptions.h b/include/clang/Sema/CodeCompleteOptions.h
index 091d8ca605..bf2e3f40c5 100644
--- a/include/clang/Sema/CodeCompleteOptions.h
+++ b/include/clang/Sema/CodeCompleteOptions.h
@@ -35,9 +35,14 @@ public:
   /// Show brief documentation comments in code completion results.
   unsigned IncludeBriefComments : 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) {}
+        IncludeNamespaceLevelDecls(1), IncludeBriefComments(0),
+        IncludeFixIts(0) {}
 };
 
 } // namespace clang
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 055d14f2d0..f3c351a161 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -10159,7 +10159,7 @@ public:
   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);