We never allowed the warnings, only made them not denied.

The global restriction is 100, but since error codes are printed out via
--explain we want to restrict them to just 80 columns.

Not doing this leads to building two copies of e.g. num_cpus in the
sysroot and _llvm deps, leading to conflicts between the two when
compiling librustc_codegen_llvm. It's not entirely clear why this is the
case after the changes in this PR but likely has something to do with a
subtle difference in ordering or similar.

Co-Authored-By: Mazdak Farrokhzad <twingoow@gmail.com>

This fixes a case where an `ignore-musl` test was not ignored on
`armv7-unknown-linux-musleabihf` because the environment did not exactly
match. Only enforce that the environment starts with the argument to
`ignore-`.

…mertj

libstd fuchsia fixes

This fixes two bugs in libstd on Fuchsia:

- `zx_time_t` was changed to an `i64`, but this never made it into libstd
- When spawning processes where any of the stdio were null, libstd attempts to open `/dev/null`, which doesn't exist on Fuchsia

r? @cramertj

…crichton

Ensure edition lints and internal lints are enabled with deny-warnings=false

Previously we only passed the deny command line flags if deny-warnings was enabled, but now we either pass -W... or -D... for each of the flags as appropriate.

This is also a breaking change to x.py as it changes `--warnings=allow` to `--warnings=warn` which is what that flag actually did; we don't have an allow warnings mode.

…acro, r=petrochenkov

Migrate internal diagnostic registration to macro_rules

Review is best done commit-by-commit.

Fixes rust-lang#64132.

Aggregation of cosmetic changes made during work on REPL PRs: libsyntax

Factored out from hacking on rustc for work on the REPL.

r? @Centril

Aggregation of cosmetic changes made during work on REPL PRs: librustc

Factored out from hacking on rustc for work on the REPL.

r? @Centril

Upgrade env_logger to 0.6

…lacrum

compiletest: Match suffixed environments

This fixes a case where an `ignore-musl` test was not ignored on
`armv7-unknown-linux-musleabihf` because the environment did not exactly
match. Only enforce that the environment starts with the argument to
`ignore-`.