[clang-tidy][NFC] Add misc-include-cleaner to clang-tidy codebase (#171903)

Enabling `misc-include-cleaner` with a couple of `IWYU pragma: keep`
lines seems beneficial to me:

In my observation, we've made far more comments in reviews like "this
header seems unused" than we've looked at includes of "top-level" files
like `ClangTidy.cpp`, `ClangTidyForceLinker.h`, `ClangTidyMain.cpp` and
so on.
So I think it's a net benefit to keep check files clean from unused
headers (which we review a lot) but make rarely-touched areas a little
"polluted" with `IWYU pragma`'s

---------

Co-authored-by: Victor Chernyakin <chernyakin.victor.j@outlook.com>

Author: vbvictor

clang-tools-extra/clang-tidy/.clang-tidy

@@ -15,6 +15,7 @@ Checks: >
   cppcoreguidelines-virtual-class-destructor,
   google-readability-casting,
   misc-const-correctness,
+  misc-include-cleaner,
   modernize-*,
   -modernize-avoid-c-arrays,
   -modernize-pass-by-value,
@@ -42,3 +43,5 @@ Checks: >
 CheckOptions:
   - key:             performance-move-const-arg.CheckTriviallyCopyableMove
     value:           false
+  - key:             misc-include-cleaner.MissingIncludes
+    value:           false

clang-tools-extra/clang-tidy/ClangTidy.cpp

@@ -33,7 +33,7 @@
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Rewrite/Frontend/FixItRewriter.h"
 #include "clang/Tooling/Core/Diagnostic.h"
-#include "clang/Tooling/DiagnosticsYaml.h"
+#include "clang/Tooling/DiagnosticsYaml.h" // IWYU pragma: keep
 #include "clang/Tooling/Refactoring.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/Process.h"

clang-tools-extra/clang-tidy/ClangTidyForceLinker.h

@@ -10,7 +10,6 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CLANGTIDYFORCELINKER_H
 
 #include "clang-tidy-config.h"
-#include "llvm/Support/Compiler.h"
 
 namespace clang::tidy {
 

clang-tools-extra/clang-tidy/GlobList.cpp

@@ -31,7 +31,7 @@ static llvm::StringRef extractNextGlob(StringRef &GlobList) {
 }
 
 static llvm::Regex createRegexFromGlob(StringRef &Glob) {
-  SmallString<128> RegexText("^");
+  llvm::SmallString<128> RegexText("^");
   const StringRef MetaChars("()^$|*+?.[]\\{}");
   for (const char C : Glob) {
     if (C == '*')

clang-tools-extra/clang-tidy/modernize/UseStdNumbersCheck.cpp

@@ -27,7 +27,6 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/FormatVariadic.h"
-#include "llvm/Support/MathExtras.h"
 #include <array>
 #include <cmath>
 #include <cstdint>

clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp

@@ -16,7 +16,6 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Debug.h"
-#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/Support/YAMLParser.h"
@@ -1363,9 +1362,8 @@ IdentifierNamingCheck::getFailureInfo(
   if (StringRef(Fixup) == Name) {
     if (!IgnoreFailedSplit) {
       LLVM_DEBUG(Location.print(llvm::dbgs(), SM);
-                 llvm::dbgs()
-                 << llvm::formatv(": unable to split words for {0} '{1}'\n",
-                                  KindName, Name));
+                 llvm::dbgs() << ": unable to split words for " << KindName
+                              << " '" << Name << "'\n");
     }
     return std::nullopt;
   }

clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp

@@ -16,14 +16,14 @@
 
 #include "ClangTidyMain.h"
 #include "../ClangTidy.h"
-#include "../ClangTidyForceLinker.h"
+#include "../ClangTidyForceLinker.h" // IWYU pragma: keep
 #include "../GlobList.h"
 #include "../utils/OptionsUtils.h"
 #include "clang/Tooling/CommonOptionsParser.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/InitLLVM.h"
-#include "llvm/Support/PluginLoader.h"
+#include "llvm/Support/PluginLoader.h" // IWYU pragma: keep
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TargetSelect.h"