In clang-tidy base checks prevent anonymous functions from triggering assertions

[bogser01]

Summary

Skeleton checks generated by clang-tidy add_check.py cause assertions to fail when run over anonymous functions(lambda functions). This patch introduces an additional check to verify that the target function is not anonymous before calling getName().
The code snippet from the [[ https://clang.llvm.org/extra/clang-tidy/Contributing.html | clang-tidy tutorial ]]is also updated.

[DavidTruby]

LGTM - please wait for someone more familiar with clang-tidy to review as well

[alexfh]

LG with a couple of comments. Do you need someone to land the patch for you?

clang-tools-extra/clang-tidy/add_new_check.py

139

No need for parentheses around this.

clang-tools-extra/docs/clang-tidy/Contributing.rst

205

ditto.

clang-tools-extra/clang-tidy/add_new_check.py

 void %(check_name)s::registerMatchers(MatchFinder *Finder) {
   // FIXME: Add matchers.
   Finder->addMatcher(functionDecl().bind("x"), this);
 }
 
 void %(check_name)s::check(const MatchFinder::MatchResult &Result) {
   // FIXME: Add callback implementation.
   const auto *MatchedDecl = Result.Nodes.getNodeAs<FunctionDecl>("x");
-  if (MatchedDecl->getName().startswith("awesome_"))
+  if ((!MatchedDecl->getIdentifier()) || MatchedDecl->getName().startswith("awesome_"))
     return;
   diag(MatchedDecl->getLocation(), "function %%0 is insufficiently awesome")
       << MatchedDecl;
   diag(MatchedDecl->getLocation(), "insert 'awesome'", DiagnosticIDs::Note)
       << FixItHint::CreateInsertion(MatchedDecl->getLocation(), "awesome_");
 }
 
 } // namespace %(namespace)s

clang-tools-extra/docs/clang-tidy/Contributing.rst

.. code-block:: c++
 
   using namespace ast_matchers;
 
   void AwesomeFunctionNamesCheck::registerMatchers(MatchFinder *Finder) {
     Finder->addMatcher(functionDecl().bind("x"), this);
   }
 
   void AwesomeFunctionNamesCheck::check(const MatchFinder::MatchResult &Result) {
-    const auto *MatchedDecl = Result.Nodes.getNodeAs<FunctionDecl>("x");
-    if (MatchedDecl->getName().startswith("awesome_"))
+    const auto *MatchedDecl = Result.Nodes.getNodeAs<FunctionDecl>("x");    
+    if ((!MatchedDecl->getIdentifier()) || MatchedDecl->getName().startswith("awesome_"))
       return;
     diag(MatchedDecl->getLocation(), "function %0 is insufficiently awesome")
         << MatchedDecl
         << FixItHint::CreateInsertion(MatchedDecl->getLocation(), "awesome_");
   }
 
 (If you want to see an example of a useful check, look at
 `clang-tidy/google/ExplicitConstructorCheck.h