[all-commits] [llvm/llvm-project] 721476: [clang] Fix a crash during code completion

[Adam Czachorowski via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 721476e6b2119a93033903109b54f429b6e8c91b
      https://github.com/llvm/llvm-project/commit/721476e6b2119a93033903109b54f429b6e8c91b
  Author: Adam Czachorowski <adamcz at google.com>
  Date:   2021-06-07 (Mon, 07 Jun 2021)

  Changed paths:
    M clang/lib/Sema/SemaLookup.cpp

  Log Message:
  -----------
  [clang] Fix a crash during code completion

During code completion, lookupInDeclContext() calls
CodeCompletionDeclConsumer::FoundDecl(),which can mutate StoredDeclsMap,
over which lookupInDeclContext() iterates. This can lead to invalidation
of iterators and an assert()-crash.

Example code where this happens:
 #include <list>
 int main() {
   std::list<int>;
   std::^
 }
with code completion on ^ with -std=c++20.

I do not have a repro case that does not need standard library.

This fix stores pointers to NamedDecls in a temporary vector, then
visits them outside of the main loop, when StoredDeclsMap iterators are
gone.

Differential Revision: https://reviews.llvm.org/D103472