[all-commits] [llvm/llvm-project] 41f946: [cmake] Limit missing external lit warning to be s...

[Dave Lee via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 41f946a6d2a4c1b36ee0a63f615a1aa6edf37cab
      https://github.com/llvm/llvm-project/commit/41f946a6d2a4c1b36ee0a63f615a1aa6edf37cab
  Author: Dave Lee <davelee.com at gmail.com>
  Date:   2020-10-13 (Tue, 13 Oct 2020)

  Changed paths:
    M llvm/cmake/modules/AddLLVM.cmake

  Log Message:
  -----------
  [cmake] Limit missing external lit warning to be shown once

When using a custom `LLVM_EXTERNAL_LIT`, it's possible the file may not exist at the CMake is generating the build. One example is LLDB standalone builds. When the external lit doesn't exist, a warning message is emitted, but the warning is printed once for every single lit target. This produces many redundant warnings.

This changes the warning to only be emitted once, controlled by a CACHE variable.

Other options are:
  1. remove the warning
  2. have callers pass an option to silence the warning if desired

See https://reviews.llvm.org/D76945 for some context.

Differential Revision: https://reviews.llvm.org/D89356