[PATCH] D93987: [ASTMatchers] Fix build when no targets are enabled

[Stephen Kelly via Phabricator via llvm-commits]

steveire added inline comments.


================
Comment at: llvm/cmake/modules/LLVM-Config.cmake:31
     set(omitted_targets ${LLVM_ALL_TARGETS})
-    list(REMOVE_ITEM omitted_targets ${LLVM_TARGETS_TO_BUILD})
+    if (LLVM_TARGETS_TO_BUILD)
+      list(REMOVE_ITEM omitted_targets ${LLVM_TARGETS_TO_BUILD})
----------------
aaron.ballman wrote:
> steveire wrote:
> > aaron.ballman wrote:
> > > I'm not a CMake expert, so can you explain what effect this change has? From the documentation (and my own limited understanding of cmake), I would have expected this to be a noop -- if the list of elements is empty, nothing will get removed from `omitted_targets`, right?
> > 
> > You can reproduce the issue in a small testcase with this file:
> > 
> > ```
> > set(omitted_targets one two three)
> > 
> > # Comment this to reproduce the failure
> > set(LLVM_TARGETS_TO_BUILD X86)
> > 
> > list(REMOVE_ITEM omitted_targets ${LLVM_TARGETS_TO_BUILD})
> > 
> > ```
> > 
> > Run this after commenting the line:
> > 
> > ```
> > $ cmake -P cmaketest.cmake
> > CMake Error at cmaketest.cmake:6 (list):
> >   list sub-command REMOVE_ITEM requires two or more arguments.
> > ```
> > 
> Huh, wow, how unintuitive! Thank you for the explanation.
Yes, I've filed https://gitlab.kitware.com/cmake/cmake/-/issues/21663


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93987/new/

https://reviews.llvm.org/D93987