[clang] Remap file path in __PRETTY_FUNCTION__

[jyyou.tw]

Summary

PRETTY_FUNCTION may have file path in template argument
but -fmacro-prefix-map can't remap it. This patch tries to fix the problem.

[dblaikie]

This seems like patching a hole, but maybe something more fundamental should be done if this remapping is meant to apply to all path rendering? (presumably there could be other bugs where these callbacks aren't applied - so is there somewhere lower level that this issue could be fixed that'd make any other callsites like this safe/correct?)

clang/lib/AST/Expr.cpp

 //===--- Expr.cpp - Expression AST Node Implementation --------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
StringRef PredefinedExpr::getIdentKindName(PredefinedExpr::IdentKind IK) {
   case LFuncSig:
     return "L__FUNCSIG__";
   case PrettyFunctionNoVirtual:
     break;
   }
   llvm_unreachable("Unknown ident kind for PredefinedExpr");
 }
 
+namespace {
+class PPCallbacks final : public PrintingCallbacks {
+  const LangOptions &LO;
+
+public:
+  PPCallbacks(const LangOptions &LO) : LO(LO) {}
+
+  std::string remapPath(StringRef Path) const override {
+    SmallString<256> Buffer(Path);
+    LO.remapPathPrefix(Buffer);
+    return static_cast<std::string>(Buffer);
+  }
+};
+} // namespace
+
 // FIXME: Maybe this should use DeclPrinter with a special "print predefined
 // expr" policy instead.
 std::string PredefinedExpr::ComputeName(IdentKind IK, const Decl *CurrentDecl) {
   ASTContext &Context = CurrentDecl->getASTContext();
 
   if (IK == PredefinedExpr::FuncDName) {
     if (const NamedDecl *ND = dyn_cast<NamedDecl>(CurrentDecl)) {
       std::unique_ptr<MangleContext> MC;
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CurrentDecl)) {
     if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
       if (MD->isVirtual() && IK != PrettyFunctionNoVirtual)
         Out << "virtual ";
       if (MD->isStatic())
         Out << "static ";
     }
 
     PrintingPolicy Policy(Context.getLangOpts());
+    PPCallbacks Callbacks(Context.getLangOpts());
+    Policy.Callbacks = &Callbacks;
+
     std::string Proto;
     llvm::raw_string_ostream POut(Proto);
 
     const FunctionDecl *Decl = FD;
     if (const FunctionDecl* Pattern = FD->getTemplateInstantiationPattern())
       Decl = Pattern;
     const FunctionType *AFT = Decl->getType()->getAs<FunctionType>();
     const FunctionProtoType *FT = nullptr;

clang/test/CodeGenCXX/macro-prefix-map.cpp

+// RUN: %clang_cc1 -fmacro-prefix-map=%p=/UNLIKELY/PATH -emit-llvm -o - %s | FileCheck %s
+//
+// CHECK: /UNLIKELY/PATH{{/|\\\\}}macro-prefix-map.cpp
+template <class T>
+const char *pretty(T) {
+  return __PRETTY_FUNCTION__;
+}
+
+const char *testEnum() {
+  enum {
+    A
+  };
+  return pretty(A);
+}