Rollup merge of rust-lang#97166 - nnethercote:move-conditions-out, r=estebank

Move conditions out of recover/report functions.

`Parser` has six recover/report functions that are passed a boolean, and
nothing is done if the boolean has a particular value.

This PR moves the tests outside the functions. This has the following effects.
- The number of lines of code goes down.
- Some `use` items become shorter.
- Avoids the strangeness whereby 11 out of 12 calls to
  `maybe_recover_from_bad_qpath` pass `true` as the second argument.
- Makes it clear at the call site that only one of
  `maybe_recover_from_bad_type_plus` and `maybe_report_ambiguous_plus` will be
  run.

r? `@estebank`

Author: JohnTitor

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1,8 +1,7 @@
 use super::pat::Expected;
-use super::ty::{AllowPlus, RecoverQuestionMark};
 use super::{
-    BlockMode, CommaRecoveryMode, Parser, PathStyle, RecoverColon, RecoverComma, Restrictions,
-    SemiColonMode, SeqSep, TokenExpectType, TokenType,
+    BlockMode, CommaRecoveryMode, Parser, PathStyle, Restrictions, SemiColonMode, SeqSep,
+    TokenExpectType, TokenType,
 };
 
 use crate::lexer::UnmatchedBrace;
@@ -1233,26 +1232,14 @@ impl<'a> Parser<'a> {
         }
     }
 
-    pub(super) fn maybe_report_ambiguous_plus(
-        &mut self,
-        allow_plus: AllowPlus,
-        impl_dyn_multi: bool,
-        ty: &Ty,
-    ) {
-        if matches!(allow_plus, AllowPlus::No) && impl_dyn_multi {
+    pub(super) fn maybe_report_ambiguous_plus(&mut self, impl_dyn_multi: bool, ty: &Ty) {
+        if impl_dyn_multi {
             self.sess.emit_err(AmbiguousPlus { sum_ty: pprust::ty_to_string(&ty), span: ty.span });
         }
     }
 
     /// Swift lets users write `Ty?` to mean `Option<Ty>`. Parse the construct and recover from it.
-    pub(super) fn maybe_recover_from_question_mark(
-        &mut self,
-        ty: P<Ty>,
-        recover_question_mark: RecoverQuestionMark,
-    ) -> P<Ty> {
-        if let RecoverQuestionMark::No = recover_question_mark {
-            return ty;
-        }
+    pub(super) fn maybe_recover_from_question_mark(&mut self, ty: P<Ty>) -> P<Ty> {
         if self.token == token::Question {
             self.bump();
             self.struct_span_err(self.prev_token.span, "invalid `?` in type")
@@ -1272,13 +1259,9 @@ impl<'a> Parser<'a> {
         }
     }
 
-    pub(super) fn maybe_recover_from_bad_type_plus(
-        &mut self,
-        allow_plus: AllowPlus,
-        ty: &Ty,
-    ) -> PResult<'a, ()> {
+    pub(super) fn maybe_recover_from_bad_type_plus(&mut self, ty: &Ty) -> PResult<'a, ()> {
         // Do not add `+` to expected tokens.
-        if matches!(allow_plus, AllowPlus::No) || !self.token.is_like_plus() {
+        if !self.token.is_like_plus() {
             return Ok(());
         }
 
@@ -1444,10 +1427,9 @@ impl<'a> Parser<'a> {
     pub(super) fn maybe_recover_from_bad_qpath<T: RecoverQPath>(
         &mut self,
         base: P<T>,
-        allow_recovery: bool,
     ) -> PResult<'a, P<T>> {
         // Do not add `::` to expected tokens.
-        if allow_recovery && self.token == token::ModSep {
+        if self.token == token::ModSep {
             if let Some(ty) = base.to_ty() {
                 return self.maybe_recover_from_bad_qpath_stage_2(ty.span, ty);
             }
@@ -1593,7 +1575,7 @@ impl<'a> Parser<'a> {
             _ => ExprKind::Await(expr),
         };
         let expr = self.mk_expr(lo.to(sp), kind, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     fn recover_await_macro(&mut self) -> PResult<'a, (Span, P<Expr>, bool)> {
@@ -2457,10 +2439,9 @@ impl<'a> Parser<'a> {
     pub(crate) fn maybe_recover_colon_colon_in_pat_typo(
         &mut self,
         mut first_pat: P<Pat>,
-        ra: RecoverColon,
         expected: Expected,
     ) -> P<Pat> {
-        if RecoverColon::Yes != ra || token::Colon != self.token.kind {
+        if token::Colon != self.token.kind {
             return first_pat;
         }
         if !matches!(first_pat.kind, PatKind::Ident(_, _, None) | PatKind::Path(..))
@@ -2594,10 +2575,9 @@ impl<'a> Parser<'a> {
     pub(crate) fn maybe_recover_unexpected_comma(
         &mut self,
         lo: Span,
-        rc: RecoverComma,
         rt: CommaRecoveryMode,
     ) -> PResult<'a, ()> {
-        if rc == RecoverComma::No || self.token != token::Comma {
+        if self.token != token::Comma {
             return Ok(());
         }
 

compiler/rustc_parse/src/parser/expr.rs

@@ -1417,7 +1417,7 @@ impl<'a> Parser<'a> {
         match self.parse_opt_lit() {
             Some(literal) => {
                 let expr = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Lit(literal), attrs);
-                self.maybe_recover_from_bad_qpath(expr, true)
+                self.maybe_recover_from_bad_qpath(expr)
             }
             None => self.try_macro_suggestion(),
         }
@@ -1444,7 +1444,7 @@ impl<'a> Parser<'a> {
             ExprKind::Tup(es)
         };
         let expr = self.mk_expr(lo.to(self.prev_token.span), kind, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     fn parse_array_or_repeat_expr(
@@ -1481,7 +1481,7 @@ impl<'a> Parser<'a> {
             }
         };
         let expr = self.mk_expr(lo.to(self.prev_token.span), kind, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     fn parse_path_start_expr(&mut self, attrs: AttrVec) -> PResult<'a, P<Expr>> {
@@ -1519,7 +1519,7 @@ impl<'a> Parser<'a> {
         };
 
         let expr = self.mk_expr(lo.to(hi), kind, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     /// Parse `'label: $expr`. The label is already parsed.
@@ -1604,7 +1604,7 @@ impl<'a> Parser<'a> {
         let lo = self.prev_token.span;
         let kind = ExprKind::Ret(self.parse_expr_opt()?);
         let expr = self.mk_expr(lo.to(self.prev_token.span), kind, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     /// Parse `"do" "yeet" expr?`.
@@ -1619,7 +1619,7 @@ impl<'a> Parser<'a> {
         let span = lo.to(self.prev_token.span);
         self.sess.gated_spans.gate(sym::yeet_expr, span);
         let expr = self.mk_expr(span, kind, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     /// Parse `"break" (('label (:? expr)?) | expr?)` with `"break"` token already eaten.
@@ -1679,7 +1679,7 @@ impl<'a> Parser<'a> {
             None
         };
         let expr = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Break(label, kind), attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     /// Parse `"yield" expr?`.
@@ -1689,7 +1689,7 @@ impl<'a> Parser<'a> {
         let span = lo.to(self.prev_token.span);
         self.sess.gated_spans.gate(sym::generators, span);
         let expr = self.mk_expr(span, kind, attrs);
-        self.maybe_recover_from_bad_qpath(expr, true)
+        self.maybe_recover_from_bad_qpath(expr)
     }
 
     /// Returns a string literal if the next token is a string literal.

compiler/rustc_parse/src/parser/pat.rs

@@ -100,8 +100,10 @@ impl<'a> Parser<'a> {
         };
 
         // Parse the first pattern (`p_0`).
-        let first_pat = self.parse_pat_no_top_alt(expected)?;
-        self.maybe_recover_unexpected_comma(first_pat.span, rc, rt)?;
+        let mut first_pat = self.parse_pat_no_top_alt(expected)?;
+        if rc == RecoverComma::Yes {
+            self.maybe_recover_unexpected_comma(first_pat.span, rt)?;
+        }
 
         // If the next token is not a `|`,
         // this is not an or-pattern and we should exit here.
@@ -111,7 +113,9 @@ impl<'a> Parser<'a> {
             // This complicated procedure is done purely for diagnostics UX.
 
             // Check if the user wrote `foo:bar` instead of `foo::bar`.
-            let first_pat = self.maybe_recover_colon_colon_in_pat_typo(first_pat, ra, expected);
+            if ra == RecoverColon::Yes {
+                first_pat = self.maybe_recover_colon_colon_in_pat_typo(first_pat, expected);
+            }
 
             if let Some(leading_vert_span) = leading_vert_span {
                 // If there was a leading vert, treat this as an or-pattern. This improves
@@ -139,7 +143,9 @@ impl<'a> Parser<'a> {
                 err.span_label(lo, WHILE_PARSING_OR_MSG);
                 err
             })?;
-            self.maybe_recover_unexpected_comma(pat.span, rc, rt)?;
+            if rc == RecoverComma::Yes {
+                self.maybe_recover_unexpected_comma(pat.span, rt)?;
+            }
             pats.push(pat);
         }
         let or_pattern_span = lo.to(self.prev_token.span);
@@ -408,7 +414,7 @@ impl<'a> Parser<'a> {
         };
 
         let pat = self.mk_pat(lo.to(self.prev_token.span), pat);
-        let pat = self.maybe_recover_from_bad_qpath(pat, true)?;
+        let pat = self.maybe_recover_from_bad_qpath(pat)?;
         let pat = self.recover_intersection_pat(pat)?;
 
         if !allow_range_pat {

compiler/rustc_parse/src/parser/stmt.rs

@@ -180,7 +180,7 @@ impl<'a> Parser<'a> {
         } else {
             // Since none of the above applied, this is an expression statement macro.
             let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac), AttrVec::new());
-            let e = self.maybe_recover_from_bad_qpath(e, true)?;
+            let e = self.maybe_recover_from_bad_qpath(e)?;
             let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
             let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
             StmtKind::Expr(e)

compiler/rustc_parse/src/parser/ty.rs

@@ -312,13 +312,18 @@ impl<'a> Parser<'a> {
         };
 
         let span = lo.to(self.prev_token.span);
-        let ty = self.mk_ty(span, kind);
+        let mut ty = self.mk_ty(span, kind);
 
         // Try to recover from use of `+` with incorrect priority.
-        self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
-        self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
-        let ty = self.maybe_recover_from_question_mark(ty, recover_question_mark);
-        self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)
+        if matches!(allow_plus, AllowPlus::Yes) {
+            self.maybe_recover_from_bad_type_plus(&ty)?;
+        } else {
+            self.maybe_report_ambiguous_plus(impl_dyn_multi, &ty);
+        }
+        if let RecoverQuestionMark::Yes = recover_question_mark {
+            ty = self.maybe_recover_from_question_mark(ty);
+        }
+        if allow_qpath_recovery { self.maybe_recover_from_bad_qpath(ty) } else { Ok(ty) }
     }
 
     /// Parses either: