On Tue Jul 14, 2026 at 9:24 PM UTC, Andrew Dunstan wrote: > Hi > > While setting up a Windows/MSVC buildfarm animal with NLS enabled, the > meson 'tmp_install' and 'initdb_cache' setup tests failed immediately > with exit status 1 and no stdout/stderr at all. > > With a little help from Claude, I (eventually) found this diagnosis and > solution: > > The root cause turned out to be in meson itself, not in our meson.build. > On Windows, determine_windows_extra_paths() in > mesonbuild/backend/backends.py builds a test's PATH by walking every > target passed via that test's 'depends:' kwarg (extra_bdeps) and adding > each one's build directory unconditionally, with no check for whether > the target actually produces a DLL. That's fine when 'depends:' lists a > handful of real link dependencies, but the 'tmp_install' test depends on > installed_targets, which includes nls_mo_targets - one custom_target per > locale/domain of compiled .mo catalogs. With NLS enabled that's several > hundred targets, none of them DLLs, none of them ever looked up via > PATH, and each one still gets its own entry. > > In our case this inflated PATH to ~39000 characters across 584 entries > (448 of them po/*/LC_MESSAGES directories), comfortably past practical > Windows environment-variable/command-line length limits, which is why > the test failed silently - the failure happens before the child process > gets a chance to produce any output. > > I think this is arguably a meson bug (determine_windows_extra_paths() > should filter extra_bdeps the same way it already filters a test > executable's own link dependencies), but regardless of whether that > gets fixed upstream, we can sidestep it on our end cheaply: depend on a > trivial stamp custom_target instead of installed_targets directly. Its > own 'depends:' still forces installed_targets to build first, so build > ordering is unaffected, but since a custom_target is not a > build.BuildTarget, meson doesn't recurse into its dependencies when > computing the test PATH - it contributes at most one harmless directory > instead of hundreds. > > I initially tried wrapping installed_targets in an alias_target() > instead, which would avoid the recursion the same way, but test()'s > 'depends:' kwarg is typechecked to only accept > BuildTarget | CustomTarget | CustomTargetIndex and rejects AliasTarget > outright: > > meson.build:NNNN:0: ERROR: test keyword argument 'depends' was of > type array[AliasTarget] but should have been type > array[BuildTarget | CustomTarget | CustomTargetIndex] > > The attached patch uses a custom_target instead, which satisfies that > type check. > > Tested on Windows/MSVC (meson 1.11.1), building with -Dnls=enabled: > > before: tmp_install test PATH = 39193 chars, 584 entries, 448 > LC_MESSAGES - tmp_install and initdb_cache setup tests FAIL > (exit status 1, no output) > after: tmp_install test PATH = 2189 chars, 43 entries, 0 > LC_MESSAGES - all three setup tests (tmp_install, > install_test_files, initdb_cache) OK > > I did not attempt to fix the same class of problem for any other test > in the tree - this patch only touches the one setup test that was > actually failing for us. If there's interest, the same technique could > presumably be applied wherever else a test's 'depends:' pulls in a > large target list.
Hey Andrew, I took some time to raise this issue with the Meson team in their Matrix/IRC channel. I'll see if the discussion goes anywhere. As for the fix and the results, they look good to me. I couldn't identify any other problems where this could be an issue, so this seems like a one-off. Did you notice any other problems? I only noticed installed_targets depended on in tmp_install and install-quiet. -- Tristan Partin PostgreSQL Contributors Team AWS (https://aws.amazon.com)
