No-opt bots should be built against an unoptimised/debug-enabled standard lib and helper libraries

[huonw]

AFAIK, the nopt-t builders do a complete bootstrap with optimisations enabled, and then build the tests without optimisations. This means the tests are built against an optimised standard library and so we don't test everything without optimisations. This will be particularly important with #17081 since debug_asserts would then be off for the vast majority of testing¹, this also means we aren't using jemalloc's consistency checks on the bots at all (#17083).

Another solution would be optimised builder with these debugging settings turned up to full.

(On the other hand, it is possible that this is already the case, in which case we should probably have bots with the debugging settings turned off.)

Nominating for something (P-low, I guess? but it would be quite nice to have these extra assurances).

¹ Unlike general inlined code which is compiled with the optimisation level of the crate it is being included in, debug_asserts are currently 'removed' in macro expansion, so any internal consistency checks of generic types like HashMap, Vec are still lost.

[brson]

For reference, the nopt-c bots build without optimizations, but don't run the tests.

[huonw]

(My implied approach, which I forgot to state, would be bootstrap with -O but build stage2 without.)

[pnkfelix]

P-low, not 1.0 blocker.

[reem]

Visiting for triage. Confirmed with @cmr on IRC that this is still a problem (no tests are run against an unoptimized build).

Unsure how to fix this, I'm not at all familiar with the build system.

[pnkfelix]

yeah to my knowledge not one of the auto-builders does a build with --enable-debug. It has allowed various bugs to creep in at times (e.g. #24405 -- would probably have been noted since the build attempt would have timed out (or taken so long), #24937 -- would definitely have been caught)

[pnkfelix]

yeah to my knowledge not one of the auto-builders does a build with --enable-debug

Note that this is supposedly no longer true; see #27010 (which has been resolved as fixed).

[alexcrichton]

We have debug assertions enabled on all bots now, so this is fixed I believe, so closing.