[CodeCompletion] Refactor: Extract two Objective-C block formatting related functions from FormatFunctionParameter

[arphaman]

Summary

This patch extracts two new functions from the function FormatFunctionParameter that are related to Objective-C block formatting. It should be two separate commits (the first extracts findTypeLocationForBlockDecl, and the second extracts formatBlockPlaceholder), but I squashed them to make the review easier.

This patch is required for my follow up patch that improves completion for block property setters.

[manmanren]

Cheers,
Manman

lib/Sema/SemaCodeComplete.cpp

2165

Please add comments for the helper function.

2285

Comments here as well.

[arphaman]

The updated patch has comments for the two extracted functions.

[manmanren]

LGTM.

Manman

lib/Sema/SemaCodeComplete.cpp

if (auto nullability = AttributedType::stripOuterNullability(Type)) {
         Result += "null_unspecified ";
         break;
       }
     }
   }
   return Result;
 }
 
+/// \brief Tries to find the most appropriate type location for an Objective-C
+/// block placeholder.
+///
+/// This function ignores things like typedefs and qualifiers in order to
+/// present the most relevant and accurate block placeholders in code completion
+/// results.
+static void findTypeLocationForBlockDecl(const TypeSourceInfo *TSInfo,
+                                         FunctionTypeLoc &Block,
+                                         FunctionProtoTypeLoc &BlockProto,
+                                         bool SuppressBlock = false) {
+  if (!TSInfo)
+    return;
+  TypeLoc TL = TSInfo->getTypeLoc().getUnqualifiedLoc();
+  while (true) {
+    // Look through typedefs.
+    if (!SuppressBlock) {
+      if (TypedefTypeLoc TypedefTL = TL.getAs<TypedefTypeLoc>()) {
+        if (TypeSourceInfo *InnerTSInfo =
+                TypedefTL.getTypedefNameDecl()->getTypeSourceInfo()) {
+          TL = InnerTSInfo->getTypeLoc().getUnqualifiedLoc();
+          continue;
+        }
+      }
+
+      // Look through qualified types
+      if (QualifiedTypeLoc QualifiedTL = TL.getAs<QualifiedTypeLoc>()) {
+        TL = QualifiedTL.getUnqualifiedLoc();
+        continue;
+      }
+
+      if (AttributedTypeLoc AttrTL = TL.getAs<AttributedTypeLoc>()) {
+        TL = AttrTL.getModifiedLoc();
+        continue;
+      }
+    }
+
+    // Try to get the function prototype behind the block pointer type,
+    // then we're done.
+    if (BlockPointerTypeLoc BlockPtr = TL.getAs<BlockPointerTypeLoc>()) {
+      TL = BlockPtr.getPointeeLoc().IgnoreParens();
+      Block = TL.getAs<FunctionTypeLoc>();
+      BlockProto = TL.getAs<FunctionProtoTypeLoc>();
+    }
+    break;
+  }
+}
+
+static std::string
+formatBlockPlaceholder(const PrintingPolicy &Policy, const NamedDecl *BlockDecl,
+                       FunctionTypeLoc &Block, FunctionProtoTypeLoc &BlockProto,
+                       bool SuppressBlock = false,
+                       Optional<ArrayRef<QualType>> ObjCSubsts = None);
+
 static std::string FormatFunctionParameter(const PrintingPolicy &Policy,
                                            const ParmVarDecl *Param,
                                            bool SuppressName = false,
                                            bool SuppressBlock = false,
                                Optional<ArrayRef<QualType>> ObjCSubsts = None) {
   bool ObjCMethodParam = isa<ObjCMethodDecl>(Param->getDeclContext());
   if (Param->getType()->isDependentType() ||
       !Param->getType()->isBlockPointerType()) {
if (ObjCMethodParam) {
       Result += Type.getAsString(Policy) + ")";
       if (Param->getIdentifier() && !SuppressName)
         Result += Param->getIdentifier()->getName();
     } else {
       Type.getAsStringInternal(Result, Policy);
     }
     return Result;
   }
-  
   // The argument for a block pointer parameter is a block literal with
   // the appropriate type.
   FunctionTypeLoc Block;
   FunctionProtoTypeLoc BlockProto;
-  TypeLoc TL;
-  if (TypeSourceInfo *TSInfo = Param->getTypeSourceInfo()) {
-    TL = TSInfo->getTypeLoc().getUnqualifiedLoc();
-    while (true) {
-      // Look through typedefs.
-      if (!SuppressBlock) {
-        if (TypedefTypeLoc TypedefTL = TL.getAs<TypedefTypeLoc>()) {
-          if (TypeSourceInfo *InnerTSInfo =
-                  TypedefTL.getTypedefNameDecl()->getTypeSourceInfo()) {
-            TL = InnerTSInfo->getTypeLoc().getUnqualifiedLoc();
-            continue;
-          }
-        }
-        
-        // Look through qualified types
-        if (QualifiedTypeLoc QualifiedTL = TL.getAs<QualifiedTypeLoc>()) {
-          TL = QualifiedTL.getUnqualifiedLoc();
-          continue;
-        }
-
-        if (AttributedTypeLoc AttrTL = TL.getAs<AttributedTypeLoc>()) {
-          TL = AttrTL.getModifiedLoc();
-          continue;
-        }
-      }
-      
-      // Try to get the function prototype behind the block pointer type,
-      // then we're done.
-      if (BlockPointerTypeLoc BlockPtr = TL.getAs<BlockPointerTypeLoc>()) {
-        TL = BlockPtr.getPointeeLoc().IgnoreParens();
-        Block = TL.getAs<FunctionTypeLoc>();
-        BlockProto = TL.getAs<FunctionProtoTypeLoc>();
-      }
-      break;
-    }
-  }
+  findTypeLocationForBlockDecl(Param->getTypeSourceInfo(), Block, BlockProto,
+                               SuppressBlock);
 
   if (!Block) {
     // We were unable to find a FunctionProtoTypeLoc with parameter names
     // for the block; just use the parameter type as a placeholder.
     std::string Result;
     if (!ObjCMethodParam && Param->getIdentifier())
       Result = Param->getIdentifier()->getName();
 
if (ObjCMethodParam) {
       Type.getAsStringInternal(Result, Policy);
     }
       
     return Result;
   }
     
   // We have the function prototype behind the block pointer type, as it was
   // written in the source.
+  return formatBlockPlaceholder(Policy, Param, Block, BlockProto, SuppressBlock,
+                                ObjCSubsts);
+}
+
+/// \brief Returns a placeholder string that corresponds to an Objective-C block
+/// declaration.
+///
+/// \param BlockDecl A declaration with an Objective-C block type.
+///
+/// \param Block The most relevant type location for that block type.
+///
+/// \param SuppressBlockName Determines wether or not the name of the block
+/// declaration is included in the resulting string.
+static std::string
+formatBlockPlaceholder(const PrintingPolicy &Policy, const NamedDecl *BlockDecl,
+                       FunctionTypeLoc &Block, FunctionProtoTypeLoc &BlockProto,
+                       bool SuppressBlock,
+                       Optional<ArrayRef<QualType>> ObjCSubsts) {
   std::string Result;
   QualType ResultType = Block.getTypePtr()->getReturnType();
   if (ObjCSubsts)
-    ResultType = ResultType.substObjCTypeArgs(Param->getASTContext(),
-                                              *ObjCSubsts,
-                                              ObjCSubstitutionContext::Result);
+    ResultType =
+        ResultType.substObjCTypeArgs(BlockDecl->getASTContext(), *ObjCSubsts,
   if (!ResultType->isVoidType() || SuppressBlock)
     ResultType.getAsStringInternal(Result, Policy);
 
   // Format the parameter list.
   std::string Params;
   if (!BlockProto || Block.getNumParams() == 0) {
     if (BlockProto && BlockProto.getTypePtr()->isVariadic())
       Params = "(...)";
     else
       Params = "(void)";
   } else {
     Params += "(";
     for (unsigned I = 0, N = Block.getNumParams(); I != N; ++I) {
       if (I)
         Params += ", ";
       Params += FormatFunctionParameter(Policy, Block.getParam(I),
                                         /*SuppressName=*/false,
-                                        /*SuppressBlock=*/true,
-                                        ObjCSubsts);
+                                        /*SuppressBlock=*/true, ObjCSubsts);
 
       if (I == N - 1 && BlockProto.getTypePtr()->isVariadic())
         Params += ", ...";
     }
     Params += ")";
   }
-  
   if (SuppressBlock) {
     // Format as a parameter.
     Result = Result + " (^";
-    if (Param->getIdentifier())
-      Result += Param->getIdentifier()->getName();
+    if (BlockDecl->getIdentifier())
+      Result += BlockDecl->getIdentifier()->getName();
     Result += ")";
     Result += Params;
   } else {
     // Format as a block literal argument.
     Result = '^' + Result;
     Result += Params;
-    
-    if (Param->getIdentifier())
-      Result += Param->getIdentifier()->getName();
+    if (BlockDecl->getIdentifier())
+      Result += BlockDecl->getIdentifier()->getName();
   }
-  
   return Result;
 }
 
 /// \brief Add function parameter chunks to the given code completion string.
 static void AddFunctionParameterChunks(Preprocessor &PP,
                                        const PrintingPolicy &Policy,
                                        const FunctionDecl *Function,
                                        CodeCompletionBuilder &Result,