[libc++] Fixes clang-tidy plugin for clang-tidy 17.

[Mordante]

Summary

When using with clang-tidy 17 Node.getAttrName() sometimes returns a
nullptr. This caused segfaults in the CI.

[philnik]

Are you sure this is expected? I can't really imagine a scenario where an attribute doesn't have a name. Clang itself also seems to assume that the pointer is non-null, since it just dereferences it instantly in quite a few places.

[Mordante]

In D151224#4365477, @philnik wrote:

Are you sure this is expected? I can't really imagine a scenario where an attribute doesn't have a name. Clang itself also seems to assume that the pointer is non-null, since it just dereferences it instantly in quite a few places.

I know the CI with clang-tidy 17 crashes, due to it. After this change it passed. Note the original code has a similar test at one place. I haven't checked what Clang does.

libcxx/test/tools/clang_tidy_checks/uglify_attributes.cpp

83

@philnik here the original code has a test too.

[philnik]

In D151224#4368627, @Mordante wrote:

In D151224#4365477, @philnik wrote:

Are you sure this is expected? I can't really imagine a scenario where an attribute doesn't have a name. Clang itself also seems to assume that the pointer is non-null, since it just dereferences it instantly in quite a few places.

I know the CI with clang-tidy 17 crashes, due to it. After this change it passed. Note the original code has a similar test at one place. I haven't checked what Clang does.

Hmm. I guess it's fine since there was a check already.

libcxx/test/tools/clang_tidy_checks/uglify_attributes.cpp

std::vector<const char*> get_standard_attributes(const clang::LangOptions& lang_opts) {
   if (CPlusPlus23(lang_opts)) {
     attributes.emplace_back("assume");
   }
 
   return attributes;
 }
 
 AST_MATCHER(clang::Attr, isPretty) {
-  if (Node.isKeywordAttribute())
+  if (Node.isKeywordAttribute() || !Node.getAttrName())
     return false;
   if (Node.isCXX11Attribute() && !Node.hasScope()) {
     if (isUgly(Node.getAttrName()->getName()))
       return false;
     return !llvm::is_contained(
         get_standard_attributes(Finder->getASTContext().getLangOpts()), Node.getAttrName()->getName());
   }
   if (Node.hasScope())
     if (!isUgly(Node.getScopeName()->getName()))
       return true;
-  if (Node.getAttrName())
-    return !isUgly(Node.getAttrName()->getName());
 
   return false;
 }
 
 std::optional<std::string> getUglyfiedCXX11Attr(const clang::Attr& attr) {
   // TODO: Don't emit FixItHints for attributes with `using` in them or emit correct fixes.
 
   std::string attr_string;