GNAT LLVM, ACATS

[Simon Wright <simon@pushface.org>]

I recently had success building GNAT_LLVM on macOS: see notes here[1].

Running ACATS 4.1 U via the ACATS Grading tools as patched for
llvm-gnat[2], I get impressively successful results: out of 4092 tests,
GCC 11.0.1 of 2021-03-31 has

Result                       Overall  B-Tests  C-Tests  L-Tests  Other Tests
[...]
** Total Failed                  44       30       14        0        0
++ Total Not-Applicable          35        0       35        0        0
!! Total Special                182      141       21       10       10
== Total Passed                3831     1272     2420       61       78

(L-tests "check that all library unit dependences within a program are
 satisfied before the program can be bound and executed, that circularity
 among units is detected, or that pragmas that apply to an entire
 partition are correctly processed".
 'Special' means human inspection needed.)

whereas llvm-gnat, built from the same GCC sources, has

Result                       Overall  B-Tests  C-Tests  L-Tests  Other Tests
[...]
** Total Failed                  48       31       17        0        0
++ Total Not-Applicable          35        0       35        0        0
!! Total Special                184      141       23       10       10
== Total Passed                3825     1271     2415       61       78

[1]
https://github.com/AdaCore/gnat-llvm/issues/20#issuecomment-809400426
[2] https://github.com/simonjwright/ACATS-grading/tree/llvm