Rollup merge of #101434 - JhonnyBillM:replace-session-for-handler-in-into-diagnostic, r=davidtwco

Update `SessionDiagnostic::into_diagnostic` to take `Handler` instead of `ParseSess`

Suggested by the team in [this Zulip Topic](https://rust-lang.zulipchat.com/#narrow/stream/336883-i18n/topic/.23100717.20SessionDiagnostic.20on.20Handler).

`Handler` already has almost all the capabilities of `ParseSess` when it comes to diagnostic emission, in this migration we only needed to add the ability to access `source_map` from the emitter in order to get a `Snippet` and the `start_point`. Not sure if adding these two methods [`span_to_snippet_from_emitter` and  `span_start_point_from_emitter`] is the best way to address this gap.

P.S. If this goes in the right direction, then we probably may want to move `SessionDiagnostic` to `rustc_errors` and rename it to `DiagnosticHandler` or something similar.

r? `@davidtwco`
r? `@compiler-errors`

1 files changed, 3 insertions, 2 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index d4828a20120..7addf519872 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1997,7 +1997,7 @@ impl<'a> Parser<'a> {
                     return Err(MissingSemicolonBeforeArray {
                         open_delim: open_delim_span,
                         semicolon: prev_span.shrink_to_hi(),
-                    }.into_diagnostic(self.sess));
+                    }.into_diagnostic(&self.sess.span_diagnostic));
                 }
                 Ok(_) => (),
                 Err(err) => err.cancel(),
@@ -2745,7 +2745,8 @@ impl<'a> Parser<'a> {
     fn parse_try_block(&mut self, span_lo: Span) -> PResult<'a, P<Expr>> {
         let (attrs, body) = self.parse_inner_attrs_and_block()?;
         if self.eat_keyword(kw::Catch) {
-            Err(CatchAfterTry { span: self.prev_token.span }.into_diagnostic(self.sess))
+            Err(CatchAfterTry { span: self.prev_token.span }
+                .into_diagnostic(&self.sess.span_diagnostic))
         } else {
             let span = span_lo.to(body.span);
             self.sess.gated_spans.gate(sym::try_blocks, span);