Compute Severity of diagnostics at birth

This commit further expand on the design for #18516 by getting rid of
the `defaultReasonSeverity` in favour of a function called
`diagReasonSeverity` which correctly takes the `DynFlags` as input. The
idea is to compute the `Severity` and the `DiagnosticReason` of each
message "at birth", without doing any later re-classifications, which
are potentially error prone, as the `DynFlags` might evolve during the
course of the program.

In preparation for a proper refactoring, now `pprWarning` from the
Parser.Ppr module has been renamed to `mkParserWarn`, which now takes a
`DynFlags` as input.

We also get rid of the reclassification we were performing inside `printOrThrowWarnings`.

Last but not least, this commit removes the need for reclassify inside GHC.Tc.Errors,
and also simplifies the implementation of `maybeReportError`.

Update Haddock submodule

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/GHC/SysTools/Process.hs b/compiler/GHC/SysTools/Process.hs
index c9cd24cf89..522c50f354 100644
--- a/compiler/GHC/SysTools/Process.hs
+++ b/compiler/GHC/SysTools/Process.hs
@@ -310,7 +310,7 @@ builderMainLoop logger dflags filter_fn pgm real_args mb_cwd mb_env = do
           logInfo logger dflags $ withPprStyle defaultUserStyle msg
           log_loop chan t
         BuildError loc msg -> do
-          putLogMsg logger dflags (mkMCDiagnostic ErrorWithoutFlag) (mkSrcSpan loc loc)
+          putLogMsg logger dflags errorDiagnostic (mkSrcSpan loc loc)
               $ withPprStyle defaultUserStyle msg
           log_loop chan t
         EOF ->