On 18/10/17 16:51 +0200, FX wrote:
Parallel builds of libstdc++ on APFS filesystem (with 1 ns granularity) on 
macOS 10.13 often fail (failure rate for “make -j2” to “make -j8” is about 60% 
from my own builds and results reported by others): 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797
This is reproducible with several versions of GNU make.

Changing libstdc++’s makefile to mark install-headers with .NOTPARALLEL fixes 
the issue. We've carried that patch in Homebrew (https://brew.sh) for a few 
months now, and have had no report of build issues since then.

Bootstrapped and regtested on x86_64-apple-darwin17 (as well as other 
platforms). OK to commit?

Could you test using .PHONY: install-headers instead?

That target *is* phony, so telling make that seems sensible.

Presumably the same change is needed for install-freestanding-headers,
since it's very similar.


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