Fix false positive in magic number checker.

cppcoreguidelines-avoid-magic-numbers should not warn about enum class.
Fixes PR40640.

1 files changed, 15 insertions, 3 deletions

diff --git a/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp b/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp
index 9114deb5c73..64806cee37e 100644
--- a/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/MagicNumbersCheck.cpp
@@ -34,7 +34,7 @@ static bool isUsedToInitializeAConstant(const MatchFinder::MatchResult &Result,
     return AsDecl->isImplicit();
   }
 
-  if (Node.get<EnumConstantDecl>() != nullptr)
+  if (Node.get<EnumConstantDecl>())
     return true;
 
   return llvm::any_of(Result.Context->getParents(Node),
@@ -125,8 +125,20 @@ bool MagicNumbersCheck::isConstant(const MatchFinder::MatchResult &Result,
         if (isUsedToInitializeAConstant(Result, Parent))
           return true;
 
-        // Ignore this instance, because this match reports the location
-        // where the template is defined, not where it is instantiated.
+        // Ignore this instance, because this matches an
+        // expanded class enumeration value.
+        if (Parent.get<CStyleCastExpr>() &&
+            llvm::any_of(
+                Result.Context->getParents(Parent),
+                [](const DynTypedNode &GrandParent) {
+                  return GrandParent.get<SubstNonTypeTemplateParmExpr>() !=
+                         nullptr;
+                }))
+          return true;
+
+        // Ignore this instance, because this match reports the
+        // location where the template is defined, not where it
+        // is instantiated.
         if (Parent.get<SubstNonTypeTemplateParmExpr>())
           return true;