rustc driver detection - includes #1897

[drahnr]

If we are not sure it's rustc like and we check -vV output to accept valid rustc drivers. Simplifies #1897 .

Fixes #861

[sylvestre]

It would be nice to update the commit to explicit why we are doing it

[drahnr]

It would be nice to update the commit to explicit why we are doing it

The commit or the PR desc? Squash merge 'd be fine by me.

[sylvestre]

The commit please

[drahnr]

Is the above sufficient @sylvestre ? I'd still be in favor of squash this PR, left the two commits separate for no particular reason other than authorship

[codecov-commenter]

Codecov Report

Attention: 127 lines in your changes are missing coverage. Please review.

Comparison is base (ffe3070) 30.77% compared to head (cbe79c9) 32.17%.
Report is 19 commits behind head on main.

Files	Patch %	Lines
src/compiler/compiler.rs	31.69%	17 Missing and 108 partials ⚠️
src/test/tests.rs	33.33%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2085      +/-   ##
==========================================
+ Coverage   30.77%   32.17%   +1.40%     
==========================================
  Files          52       53       +1     
  Lines       19913    20721     +808     
  Branches     9630    10296     +666     
==========================================
+ Hits         6129     6668     +539     
+ Misses       7959     7877      -82     
- Partials     5825     6176     +351     

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[drahnr]

The coverage report is obsolete, it actually improved marginally.

CC @sylvestre anything missing/insufficient, otherwise I'd merge with rebase?