refactor: extract final rustc_parse touchpoint from macros.rs

Author: calebcartwright

src/macros.rs

@@ -29,7 +29,7 @@ use crate::expr::{rewrite_array, rewrite_assign_rhs, RhsAssignKind};
 use crate::lists::{itemize_list, write_list, ListFormatting};
 use crate::overflow;
 use crate::parse::macros::lazy_static::parse_lazy_static;
-use crate::parse::macros::{build_parser, parse_macro_args, ParsedMacroArgs};
+use crate::parse::macros::{parse_expr, parse_macro_args, ParsedMacroArgs};
 use crate::rewrite::{Rewrite, RewriteContext};
 use crate::shape::{Indent, Shape};
 use crate::source_map::SpanUtils;
@@ -1060,11 +1060,10 @@ pub(crate) fn convert_try_mac(
     let path = &pprust::path_to_string(&mac.path);
     if path == "try" || path == "r#try" {
         let ts = mac.args.inner_tokens();
-        let mut parser = build_parser(context, ts);
 
         Some(ast::Expr {
             id: ast::NodeId::root(), // dummy value
-            kind: ast::ExprKind::Try(parser.parse_expr().ok()?),
+            kind: ast::ExprKind::Try(parse_expr(context, ts)?),
             span: mac.span(), // incorrect span, but shouldn't matter too much
             attrs: ast::AttrVec::new(),
             tokens: None,

src/parse/macros/mod.rs

@@ -13,7 +13,7 @@ use crate::rewrite::{Rewrite, RewriteContext};
 
 pub(crate) mod lazy_static;
 
-pub(crate) fn build_parser<'a>(context: &RewriteContext<'a>, tokens: TokenStream) -> Parser<'a> {
+fn build_parser<'a>(context: &RewriteContext<'a>, tokens: TokenStream) -> Parser<'a> {
     stream_to_parser(context.parse_sess.inner(), tokens, MACRO_ARGUMENTS)
 }
 
@@ -155,6 +155,14 @@ pub(crate) fn parse_macro_args(
     })
 }
 
+pub(crate) fn parse_expr(
+    context: &RewriteContext<'_>,
+    tokens: TokenStream,
+) -> Option<ptr::P<ast::Expr>> {
+    let mut parser = build_parser(context, tokens);
+    parser.parse_expr().ok()
+}
+
 const RUST_KW: [Symbol; 59] = [
     kw::PathRoot,
     kw::DollarCrate,