[all-commits] [llvm/llvm-project] 75196b: [llvm-lib] Add /WX, warn by default on empty input...
Nico Weber via All-commits
all-commits at lists.llvm.org
Mon Apr 11 10:15:50 PDT 2022
Author: Nico Weber <thakis at chromium.org>
Date: 2022-04-11 (Mon, 11 Apr 2022)
[llvm-lib] Add /WX, warn by default on empty inputs, add opt-out
lib.exe by default exits successfully without writing an output
file when no inputs are passed. llvm-lib has the same behavior,
This behavior interacts poorly with build systems: If a static
library target had no inputs, llvm-lib would not produce an output
file, causing ninja (or make, or a similar system) to successfully
run that step, but then re-run it on the next build.
After this patch, llvm-lib emits a warning in this case, that with
/WX can be turned into an error. That way, ninja (or make, or...)
will mark the initial build as failed.
People who don't like the warning can use /ignore:emptyoutput to
The warning also points out the existing flag /llvmlibempty which
forces creation of an empty .lib file (this is an extension to lib.exe).
Differential Revision: https://reviews.llvm.org/D123517
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