Extend shelf-life by 70 years

[bmwiedemann]

Summary

Without this patch, tests would fail after 2030.

Note: requires timestamps with more than 31 bits

[RKSimon]

Sorry I'm not the right person to review this - adding some other potentials

[bmwiedemann]

I tested now, that it still works on i586 (in addition to x86_64)

[bruno]

Out of curiosity, why? If it makes you happy though, go for it! LGTM

[rsmith]

I'm assuming this is a patch from a time traveller who has come back from 11 years in the future seeking to prevent some disaster, after this test case somehow becomes part of some critical infrastructure. Definitely don't want to stand in the way of that!

[bmwiedemann]

As to the why: I'm working on reproducible builds for openSUSE and for that I verify that our packages can still give identical build results 15 years from now (which is the expected lifetime of today's enterprise software). kvm -rtc base option helps there.
Sometimes I even make it +20 years to find year-2038 bugs such as those in ninja and python, because it is better to fix them now rather than be surprised later and have a hard time with plenty busy work getting the fixes everywhere in time.

Now, it would be nice if someone could push this patch to the git repo.
I already got 200+ forks in my github home - most with just 1 small patch that eventually gets merged.

[bmwiedemann]

Can someone please merge this change?

[aaron.ballman]

In D52967#1494969, @bmwiedemann wrote:

Can someone please merge this change?

I commit the change in r360254, thank you for the patch!

test/Modules/fmodules-validate-once-per-build-session.c

 // RUN: cp %t/modules-cache/Foo.pcm %t/modules-to-compare/Foo-after.pcm
 // RUN: cp %t/modules-cache-user/Foo.pcm %t/modules-to-compare/Foo-after-user.pcm
 
 // RUN: diff %t/modules-to-compare/Foo-before.pcm %t/modules-to-compare/Foo-after.pcm
 // When foo.h is a user header, we will always validate it.
 // RUN: not diff %t/modules-to-compare/Foo-before-user.pcm %t/modules-to-compare/Foo-after-user.pcm
 
 // ===
-// Recompile the module if the today's date is before 01 January 2030.
-// RUN: %clang_cc1 -cc1 -fmodules -fimplicit-module-maps -fdisable-module-hash -fmodules-cache-path=%t/modules-cache -fsyntax-only -isystem %t/Inputs -fbuild-session-timestamp=1893456000 -fmodules-validate-once-per-build-session %s
+// Recompile the module if the today's date is before 01 January 2100.
+// RUN: %clang_cc1 -cc1 -fmodules -fimplicit-module-maps -fdisable-module-hash -fmodules-cache-path=%t/modules-cache -fsyntax-only -isystem %t/Inputs -fbuild-session-timestamp=4102441200 -fmodules-validate-once-per-build-session %s
 // RUN: ls -R %t/modules-cache | grep Foo.pcm.timestamp
 // RUN: cp %t/modules-cache/Foo.pcm %t/modules-to-compare/Foo-after.pcm
 
 // RUN: not diff %t/modules-to-compare/Foo-before.pcm %t/modules-to-compare/Foo-after.pcm