[PATCH] D93688: [ASTMatchers] Ensure that we can match inside lambdas

[Alexander Kornienko via Phabricator via cfe-commits]

alexfh added a comment.

In D93688#2525947 <https://reviews.llvm.org/D93688#2525947>, @alexfh wrote:

> This patch causes practically infinite traversal times on code that contains deeply nested lambdas. I'll try to get a suitable repro, but could you maybe revert this in the meantime?

Actually, there's a very simple test case:

  void f() {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    [] {
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
    }();
  }

It looks like each lambda traversal triggers multiple traversals of the same AST fragment causing exponential growth of the traversal time.


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