[clang-tools-extra] [clang-tidy] Update llvmlibc-implementation-in-namespace to new rules (PR #66504)

[Guillaume Chatelet via cfe-commits]

================
@@ -30,15 +32,18 @@ void ImplementationInNamespaceCheck::check(
     return;
 
   if (const auto *NS = dyn_cast<NamespaceDecl>(MatchedDecl)) {
-    if (NS->getName() != RequiredNamespace) {
-      diag(NS->getLocation(), "'%0' needs to be the outermost namespace")
-          << RequiredNamespace;
-    }
+    if (!Result.SourceManager->isMacroBodyExpansion(NS->getLocation()))
+      diag(NS->getLocation(),
+           "the outermost namespace should be the '%0' macro")
+          << RequiredNamespaceMacroName;
+    else if (!NS->getName().starts_with(RequiredNamespaceStart))
+      diag(NS->getLocation(), "the outermost namespace should start with '%0'")
+          << RequiredNamespaceStart;
     return;
   }
   diag(MatchedDecl->getLocation(),
----------------
gchatelet wrote:

This is the case where we are not in any namespace but the message is misleading. Thx for pointing this out. I'll fix it shortly.

https://github.com/llvm/llvm-project/pull/66504