[SemaCodeComplete] Expose a method to create CodeCompletionString for macros.

[ioeric]

Summary

The method only takes PPreprocessor and don't require structures that
might not be available (e.g. Sema and ASTContext) when CodeCompletionString
needs to be generated for macros.

[sammccall]

Could you give a little more context about how this will be used? (where the completion items come from, and when the strings will get built)

include/clang/Sema/CodeCompleteConsumer.h

921

please document the new function - particularly why it's different and what's the use case it supports
(if I understand right, it's to allow storing CodeCompletionResult instances for later stringification only when they're for macros - why?)

One of the args you're *not* taking here is ASTContext, but if I understand right it must still be alive: this->Macro points into the IdentifierTable which is owned by ASTContext.
In some sense taking this arg seems like a safety feature!

[ioeric]

• Addressed review comments.

include/clang/Sema/CodeCompleteConsumer.h

921

Done. Added documentation.

One of the args you're *not* taking here is ASTContext, but if I understand right it must still be alive: this->Macro points into the IdentifierTable which is owned by ASTContext.

ASTContext might not be available during preprocessing. It turned out that ASTContext only holds a reference to the IdentifierTable which is owned by the Preprocessor, so requiring a Preprocessor should be safe.

[sammccall]

Thanks for the explanation!

[ioeric]

• Merged with orgin/master

include/clang/Sema/CodeCompleteConsumer.h

CodeCompletionString *CreateCodeCompletionString(Sema &S,
                                            CodeCompletionTUInfo &CCTUInfo,
                                            bool IncludeBriefComments);
   CodeCompletionString *CreateCodeCompletionString(ASTContext &Ctx,
                                                    Preprocessor &PP,
                                          const CodeCompletionContext &CCContext,
                                            CodeCompletionAllocator &Allocator,
                                            CodeCompletionTUInfo &CCTUInfo,
                                            bool IncludeBriefComments);
+  /// Creates a new code-completion string for the macro result. Similar to the
+  /// above overloads, except this only requires preprocessor information.
+  /// The result kind must be `RK_Macro`.
+  CodeCompletionString *
+  CreateCodeCompletionStringForMacro(Preprocessor &PP,
+                                     CodeCompletionAllocator &Allocator,
+                                     CodeCompletionTUInfo &CCTUInfo);
 
   /// Retrieve the name that should be used to order a result.
   ///
   /// If the name needs to be constructed as a string, that string will be
   /// saved into Saved and the returned StringRef will refer to it.
   StringRef getOrderedName(std::string &Saved) const;
 
 private:

lib/Sema/SemaCodeComplete.cpp

CodeCompletionString *CodeCompletionResult::CreateCodeCompletionString(Sema &S,
                                          const CodeCompletionContext &CCContext,
                                          CodeCompletionAllocator &Allocator,
                                          CodeCompletionTUInfo &CCTUInfo,
                                          bool IncludeBriefComments) {
   return CreateCodeCompletionString(S.Context, S.PP, CCContext, Allocator,
                                     CCTUInfo, IncludeBriefComments);
 }
 
-/// If possible, create a new code completion string for the given
-/// result.
-///
-/// \returns Either a new, heap-allocated code completion string describing
-/// how to use this result, or NULL to indicate that the string or name of the
-/// result is all that is needed.
-CodeCompletionString *
-CodeCompletionResult::CreateCodeCompletionString(ASTContext &Ctx,
-                                                 Preprocessor &PP,
-                                         const CodeCompletionContext &CCContext,
-                                           CodeCompletionAllocator &Allocator,
-                                           CodeCompletionTUInfo &CCTUInfo,
-                                           bool IncludeBriefComments) {
+CodeCompletionString *CodeCompletionResult::CreateCodeCompletionStringForMacro(
+    Preprocessor &PP, CodeCompletionAllocator &Allocator,
+    CodeCompletionTUInfo &CCTUInfo) {
+  assert(Kind == RK_Macro);
   CodeCompletionBuilder Result(Allocator, CCTUInfo, Priority, Availability);
-
-  PrintingPolicy Policy = getCompletionPrintingPolicy(Ctx, PP);
-  if (Kind == RK_Pattern) {
-    Pattern->Priority = Priority;
-    Pattern->Availability = Availability;
-
-    if (Declaration) {
-      Result.addParentContext(Declaration->getDeclContext());
-      Pattern->ParentName = Result.getParentName();
-      if (const RawComment *RC =
-              getPatternCompletionComment(Ctx, Declaration)) {
-        Result.addBriefComment(RC->getBriefText(Ctx));
-        Pattern->BriefComment = Result.getBriefComment();
-      }
-    }
-
-    return Pattern;
-  }
-
-  if (Kind == RK_Keyword) {
-    Result.AddTypedTextChunk(Keyword);
-    return Result.TakeString();
-  }
-
-  if (Kind == RK_Macro) {
-    const MacroInfo *MI = PP.getMacroInfo(Macro);
-    Result.AddTypedTextChunk(
-                            Result.getAllocator().CopyString(Macro->getName()));
+  Result.AddTypedTextChunk(Result.getAllocator().CopyString(Macro->getName()));
 
-    if (!MI || !MI->isFunctionLike())
-      return Result.TakeString();
 
-    // Format a function-like macro with placeholders for the arguments.
-    Result.AddChunk(CodeCompletionString::CK_LeftParen);
-    MacroInfo::param_iterator A = MI->param_begin(), AEnd = MI->param_end();
 
-    // C99 variadic macros add __VA_ARGS__ at the end. Skip it.
-    if (MI->isC99Varargs()) {
-      --AEnd;
 
-      if (A == AEnd) {
-        Result.AddPlaceholderChunk("...");
-      }
-    }
 
-    for (MacroInfo::param_iterator A = MI->param_begin(); A != AEnd; ++A) {
-      if (A != MI->param_begin())
-        Result.AddChunk(CodeCompletionString::CK_Comma);
 
-      if (MI->isVariadic() && (A+1) == AEnd) {
-        SmallString<32> Arg = (*A)->getName();
-        if (MI->isC99Varargs())
-          Arg += ", ...";
-        else
-          Arg += "...";
-        Result.AddPlaceholderChunk(Result.getAllocator().CopyString(Arg));
-        break;
-      }
+    if (MI->isVariadic() && (A + 1) == AEnd) {
 
-      // Non-variadic macros are simple.
-      Result.AddPlaceholderChunk(
-                          Result.getAllocator().CopyString((*A)->getName()));
-    }
-    Result.AddChunk(CodeCompletionString::CK_RightParen);
-    return Result.TakeString();
-  }
 
+/// If possible, create a new code completion string for the given
+/// result.
+///
+/// \returns Either a new, heap-allocated code completion string describing
+/// how to use this result, or NULL to indicate that the string or name of the
+/// result is all that is needed.
+CodeCompletionString *
+CodeCompletionResult::CreateCodeCompletionString(ASTContext &Ctx,
+                                                 Preprocessor &PP,
+                                         const CodeCompletionContext &CCContext,
+                                           CodeCompletionAllocator &Allocator,
+                                           CodeCompletionTUInfo &CCTUInfo,
+                                           bool IncludeBriefComments) {
+  if (Kind == RK_Macro)
+    return CreateCodeCompletionStringForMacro(PP, Allocator, CCTUInfo);
+
+  CodeCompletionBuilder Result(Allocator, CCTUInfo, Priority, Availability);
+
+  PrintingPolicy Policy = getCompletionPrintingPolicy(Ctx, PP);
+  if (Kind == RK_Pattern) {
+    Pattern->Priority = Priority;
+    Pattern->Availability = Availability;
+
+    if (Declaration) {
+      Result.addParentContext(Declaration->getDeclContext());
+      Pattern->ParentName = Result.getParentName();
+      if (const RawComment *RC =
+              getPatternCompletionComment(Ctx, Declaration)) {
+        Result.addBriefComment(RC->getBriefText(Ctx));
+        Pattern->BriefComment = Result.getBriefComment();
+      }
+    }
+
+    return Pattern;
+  }
+
+  if (Kind == RK_Keyword) {
+    Result.AddTypedTextChunk(Keyword);
+    return Result.TakeString();
+  }
   assert(Kind == RK_Declaration && "Missed a result kind?");
   const NamedDecl *ND = Declaration;
   Result.addParentContext(ND->getDeclContext());
 
   if (IncludeBriefComments) {
     // Add documentation comment, if it exists.
     if (const RawComment *RC = getCompletionComment(Ctx, Declaration)) {
       Result.addBriefComment(RC->getBriefText(Ctx));