Contribute DiagnosticCountInPassHook

[vlstill]

This is the reason behind #4626. A pass manager hook that is useful for testing (p4test-like) the compiler output or just for the developers to see what passes emit diagnostic messages.

Example output (with the hook in driver added and running with -TdiagnosticCountInPass:1):

main.p4(65): [--Wwarn=parser-transition] warning: sub_parser: implicit transition to `reject'
           state sub_parser{
                 ^^^^^^^^^^
PASS FrontEnd ~> CreateBuiltins emitted 1 warning
[--Wwarn=parser-transition] warning: SelectCase: unreachable case
PASS MidEnd ~> PassRepeated emitted 1 warning

[fruffy]

Could be nice to have an example exercising this hook.

[vlstill]

Could be nice to have an example exercising this hook.

Let me at it to P4test, the output has to be enabled anyway so it should not break anything.

[vlstill]

$ ./p4c/p4test -TdiagnosticCountInPass:1 <(printf 'const bit<42> x = -4;\nconst bit<16> y = (bit<16>)x;\nvoid foo() { return 4; }')
/dev/fd/63(1): [--Wwarn=mismatch] warning: -42w4: negative value with unsigned type
const bit<42> x = -4;
                   ^
/dev/fd/63(1): [--Wwarn=mismatch] warning: 16w4398046511100: value does not fit in 16 bits
const bit<42> x = -4;
                   ^
PASS ConstantFolding ~> DoConstantFolding emitted 2 warnings
/dev/fd/63(3): [--Werror=type-error] error: return 4: return expression in function with void return
void foo() { return 4; }
             ^^^^^^
PASS FrontEnd ~> P4::TypeInference emitted 1 error

[vlstill]

I've further extended this to provide better info in cases like parser errors:

$ ./p4c/p4test -TdiagnosticCountInPass:1 <(printf 'const bit<42> x = -4;\nconst bit<16> y = (bit<16>)x\nvoid foo() { return 4; }')                                     /dev/fd/63(3):syntax error, unexpected VOID, expecting ;
void
^^^^
[--Werror=overlimit] error: 1 errors encountered, aborting compilation
PARSER emitted 2 errors

[vlstill]

Any idea what is wrong with the Fedora build?

/__w/p4c/p4c/build/_deps/abseil-src/absl/numeric/internal/bits.h:309:24: error: '__builtin_ctzs' needs isa option -mbmi

[fruffy]

Any idea what is wrong with the Fedora build?

/__w/p4c/p4c/build/_deps/abseil-src/absl/numeric/internal/bits.h:309:24: error: '__builtin_ctzs' needs isa option -mbmi

It looks like Fedora GCC switched from 13 to 14 and this instruction now needs an option.