The tab replacement for diagnostics added in #79757 included a few assertions to
ensure all tab characters are handled appropriately. We've started getting
reports of these assertions firing (#81614). Since it's only a cosmetic issue,
this downgrades the assertions to debug only, so we at least continue compiling
even if the diagnostics might be a tad wonky.
Fixes#81614
This replaces tabs earlier in the diagnostics emitting process, which allows
various margin calculations to ignore the existence of tabs. It does add a
string copy for the source lines that are emitted.
Properly handle lint spans after MIR inlining
The first commit shows what happens when we apply mir inlining and then cause lints on the inlined MIR.
The second commit fixes that.
r? `@wesleywiser`
