[clang-tidy] Don't emit the whole spelling include header in include-cleaner diagnostic message

[hokein]

Summary

To keep the message short and consistent with clangd, and the diagnostics are
attached to the #include line, users have enough context to understand the whole #include.

clang-tools-extra/clang-tidy/misc/IncludeCleanerCheck.cpp

 #include "clang/Lex/Preprocessor.h"
 #include "clang/Tooling/Core/Replacement.h"
 #include "clang/Tooling/Inclusions/HeaderIncludes.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
 #include <optional>
 #include <string>
 #include <vector>
 
 using namespace clang::ast_matchers;
 
 namespace clang::tidy::misc {
auto FileStyle =
       format::getStyle(format::DefaultFormatStyle, getCurrentMainFile(),
                        format::DefaultFallbackStyle, Code,
                        &SM->getFileManager().getVirtualFileSystem());
   if (!FileStyle)
     FileStyle = format::getLLVMStyle();
 
   for (const auto *Inc : Unused) {
     diag(Inc->HashLocation, "included header %0 is not used directly")
-        << Inc->quote()
+        << llvm::sys::path::filename(Inc->Spelled,
+                                     llvm::sys::path::Style::posix)
         << FixItHint::CreateRemoval(CharSourceRange::getCharRange(
                SM->translateLineCol(SM->getMainFileID(), Inc->Line, 1),
                SM->translateLineCol(SM->getMainFileID(), Inc->Line + 1, 1)));
   }
 
   tooling::HeaderIncludes HeaderIncludes(getCurrentMainFile(), Code,
                                          FileStyle->IncludeStyle);
   for (const auto &Inc : Missing) {

clang-tools-extra/test/clang-tidy/checkers/misc/include-cleaner.cpp

 // RUN: %check_clang_tidy %s misc-include-cleaner %t -- -- -I%S/Inputs -isystem%S/Inputs/system
 #include "bar.h"
 // CHECK-FIXES: {{^}}#include "baz.h"{{$}}
 #include "foo.h"
-// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: included header "foo.h" is not used directly [misc-include-cleaner]
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: included header foo.h is not used directly [misc-include-cleaner]
 // CHECK-FIXES: {{^}}
 // CHECK-FIXES: {{^}}#include <string>{{$}}
 #include <vector.h>
-// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: included header <vector.h> is not used directly [misc-include-cleaner]
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: included header vector.h is not used directly [misc-include-cleaner]
 // CHECK-FIXES: {{^}}
 int BarResult = bar();
 int BazResult = baz();
 // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: no header providing "baz" is directly included [misc-include-cleaner]
 std::string HelloString;
 // CHECK-MESSAGES: :[[@LINE-1]]:6: warning: no header providing "std::string" is directly included [misc-include-cleaner]
 int FooBarResult = foobar();
 // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: no header providing "foobar" is directly included [misc-include-cleaner]