[CodeCompletion][clangd] Clean __uglified parameter names in completion & hover

Underscore-uglified identifiers are used in standard library implementations to
guard against collisions with macros, and they hurt readability considerably.
(Consider `push_back(Tp_ &&__value)` vs `push_back(Tp value)`.
When we're describing an interface, the exact names of parameters are not
critical so we can drop these prefixes.

This patch adds a new PrintingPolicy flag that can applies this stripping
when recursively printing pieces of AST.
We set it in code completion/signature help, and in clangd's hover display.
All three features also do a bit of manual poking at names, so fix up those too.

Fixes https://github.com/clangd/clangd/issues/736

Differential Revision: https://reviews.llvm.org/D116387

1 files changed, 8 insertions, 7 deletions

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index b86bfe8..01fdf51 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -1896,6 +1896,7 @@ static PrintingPolicy getCompletionPrintingPolicy(const ASTContext &Context,
   Policy.SuppressStrongLifetime = true;
   Policy.SuppressUnwrittenScope = true;
   Policy.SuppressScope = true;
+  Policy.CleanUglifiedParameters = true;
   return Policy;
 }
 
@@ -2837,7 +2838,7 @@ FormatFunctionParameter(const PrintingPolicy &Policy,
     std::string Result;
 
     if (Param->getIdentifier() && !ObjCMethodParam && !SuppressName)
-      Result = std::string(Param->getIdentifier()->getName());
+      Result = std::string(Param->getIdentifier()->deuglifiedName());
 
     QualType Type = Param->getType();
     if (ObjCSubsts)
@@ -2847,7 +2848,7 @@ FormatFunctionParameter(const PrintingPolicy &Policy,
       Result = "(" + formatObjCParamQualifiers(ObjCQual, Type);
       Result += Type.getAsString(Policy) + ")";
       if (Param->getIdentifier() && !SuppressName)
-        Result += Param->getIdentifier()->getName();
+        Result += Param->getIdentifier()->deuglifiedName();
     } else {
       Type.getAsStringInternal(Result, Policy);
     }
@@ -2875,7 +2876,7 @@ FormatFunctionParameter(const PrintingPolicy &Policy,
     // for the block; just use the parameter type as a placeholder.
     std::string Result;
     if (!ObjCMethodParam && Param->getIdentifier())
-      Result = std::string(Param->getIdentifier()->getName());
+      Result = std::string(Param->getIdentifier()->deuglifiedName());
 
     QualType Type = Param->getType().getUnqualifiedType();
 
@@ -2887,7 +2888,7 @@ FormatFunctionParameter(const PrintingPolicy &Policy,
       if (Result.back() != ')')
         Result += " ";
       if (Param->getIdentifier())
-        Result += Param->getIdentifier()->getName();
+        Result += Param->getIdentifier()->deuglifiedName();
     } else {
       Type.getAsStringInternal(Result, Policy);
     }
@@ -3082,14 +3083,14 @@ static void AddTemplateParameterChunks(
 
       if (TTP->getIdentifier()) {
         PlaceholderStr += ' ';
-        PlaceholderStr += TTP->getIdentifier()->getName();
+        PlaceholderStr += TTP->getIdentifier()->deuglifiedName();
       }
 
       HasDefaultArg = TTP->hasDefaultArgument();
     } else if (NonTypeTemplateParmDecl *NTTP =
                    dyn_cast<NonTypeTemplateParmDecl>(*P)) {
       if (NTTP->getIdentifier())
-        PlaceholderStr = std::string(NTTP->getIdentifier()->getName());
+        PlaceholderStr = std::string(NTTP->getIdentifier()->deuglifiedName());
       NTTP->getType().getAsStringInternal(PlaceholderStr, Policy);
       HasDefaultArg = NTTP->hasDefaultArgument();
     } else {
@@ -3101,7 +3102,7 @@ static void AddTemplateParameterChunks(
       PlaceholderStr = "template<...> class";
       if (TTP->getIdentifier()) {
         PlaceholderStr += ' ';
-        PlaceholderStr += TTP->getIdentifier()->getName();
+        PlaceholderStr += TTP->getIdentifier()->deuglifiedName();
       }
 
       HasDefaultArg = TTP->hasDefaultArgument();