refactor implement

Author: HerrCai0907

clang-tools-extra/clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.cpp

@@ -19,6 +19,7 @@
 #include "llvm/ADT/SmallVector.h"
 
 #include <cstdint>
+#include <optional>
 
 using namespace clang::ast_matchers;
 
@@ -48,7 +49,7 @@ NarrowingConversionsCheck::NarrowingConversionsCheck(StringRef Name,
                                                      ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
       WarnOnIntegerNarrowingConversion(
-          Options.get("WarnOnIntegerNarrowingConversion", true)),
+          Options.get<bool>("WarnOnIntegerNarrowingConversion")),
       WarnOnIntegerToFloatingPointNarrowingConversion(
           Options.get("WarnOnIntegerToFloatingPointNarrowingConversion", true)),
       WarnOnFloatingPointNarrowingConversion(
@@ -61,8 +62,9 @@ NarrowingConversionsCheck::NarrowingConversionsCheck(StringRef Name,
 
 void NarrowingConversionsCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
-  Options.store(Opts, "WarnOnIntegerNarrowingConversion",
-                WarnOnIntegerNarrowingConversion);
+  if (WarnOnIntegerNarrowingConversion.has_value())
+    Options.store(Opts, "WarnOnIntegerNarrowingConversion",
+                  WarnOnIntegerNarrowingConversion.value());
   Options.store(Opts, "WarnOnIntegerToFloatingPointNarrowingConversion",
                 WarnOnIntegerToFloatingPointNarrowingConversion);
   Options.store(Opts, "WarnOnFloatingPointNarrowingConversion",
@@ -392,13 +394,13 @@ void NarrowingConversionsCheck::handleIntegralCast(const ASTContext &Context,
                                                    SourceLocation SourceLoc,
                                                    const Expr &Lhs,
                                                    const Expr &Rhs) {
-  if (WarnOnIntegerNarrowingConversion) {
-    // From [conv.integral] since C++20
-    // The result is the unique value of the destination type that is congruent
-    // to the source integer modulo 2^N, where N is the width of the destination
-    // type.
-    if (getLangOpts().CPlusPlus20)
-      return;
+  // From [conv.integral] since C++20
+  // The result is the unique value of the destination type that is congruent
+  // to the source integer modulo 2^N, where N is the width of the destination
+  // type.
+  const bool ActualWarnOnIntegerNarrowingConversion =
+      WarnOnIntegerNarrowingConversion.value_or(!getLangOpts().CPlusPlus20);
+  if (ActualWarnOnIntegerNarrowingConversion) {
     const BuiltinType *ToType = getBuiltinType(Lhs);
     // From [conv.integral] before C++20:
     // Conversions to unsigned integer is well defined so no warning is issued.

clang-tools-extra/clang-tidy/cppcoreguidelines/NarrowingConversionsCheck.h

@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_NARROWING_CONVERSIONS_H
 
 #include "../ClangTidyCheck.h"
+#include <optional>
 
 namespace clang::tidy::cppcoreguidelines {
 
@@ -95,7 +96,7 @@ class NarrowingConversionsCheck : public ClangTidyCheck {
                                           const BuiltinType &FromType,
                                           const BuiltinType &ToType) const;
 
-  const bool WarnOnIntegerNarrowingConversion;
+  const std::optional<bool> WarnOnIntegerNarrowingConversion;
   const bool WarnOnIntegerToFloatingPointNarrowingConversion;
   const bool WarnOnFloatingPointNarrowingConversion;
   const bool WarnWithinTemplateInstantiation;

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/narrowing-conversions.rst

@@ -12,7 +12,7 @@ This check implements `ES.46
 from the C++ Core Guidelines.
 
 We enforce only part of the guideline, more specifically, we flag narrowing conversions from:
- - an integer to a narrower integer before C++20 (e.g. ``char`` to ``unsigned char``)
+ - an integer to a narrower integer (e.g. ``char`` to ``unsigned char``)
    if WarnOnIntegerNarrowingConversion Option is set,
  - an integer to a narrower floating-point (e.g. ``uint64_t`` to ``float``)
    if WarnOnIntegerToFloatingPointNarrowingConversion Option is set,
@@ -34,7 +34,9 @@ Options
 .. option:: WarnOnIntegerNarrowingConversion
 
     When `true`, the check will warn on narrowing integer conversion
-    (e.g. ``int`` to ``size_t``). `true` by default.
+    (e.g. ``int`` to ``size_t``).
+    Before C++20 `true` by default.
+    Since C++20 `false` by default.
 
 .. option:: WarnOnIntegerToFloatingPointNarrowingConversion