Rollup merge of #119380 - ShE3py:match-never-pat, r=petrochenkov

matthiaskrgr · web-flow · commit e8831b6df892 · 2023-12-28T18:48:02.000+01:00
Don't suggest writing a bodyless arm if the pattern can never be a never pattern #118527 enabled arms to be bodyless for never patterns ; this PR removes the `,` and `}` suggestions for patterns that could never be never patterns.
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
@@ -2937,7 +2937,13 @@ impl<'a> Parser<'a> {
             let is_almost_fat_arrow = TokenKind::FatArrow
                 .similar_tokens()
                 .is_some_and(|similar_tokens| similar_tokens.contains(&this.token.kind));
-            let mut result = if !is_fat_arrow && !is_almost_fat_arrow {
+
+            // this avoids the compiler saying that a `,` or `}` was expected even though
+            // the pattern isn't a never pattern (and thus an arm body is required)
+            let armless = (!is_fat_arrow && !is_almost_fat_arrow && pat.could_be_never_pattern())
+                || matches!(this.token.kind, token::Comma | token::CloseDelim(Delimiter::Brace));
+
+            let mut result = if armless {
                 // A pattern without a body, allowed for never patterns.
                 arm_body = None;
                 this.expect_one_of(&[token::Comma], &[token::CloseDelim(Delimiter::Brace)]).map(
diff --git a/tests/ui/half-open-range-patterns/range_pat_interactions1.rs b/tests/ui/half-open-range-patterns/range_pat_interactions1.rs
@@ -17,7 +17,7 @@ fn main() {
         }
         match x as i32 {
             0..5+1 => errors_only.push(x),
-            //~^ error: expected one of `,`, `=>`, `if`, `|`, or `}`, found `+`
+            //~^ error: expected one of `=>`, `if`, or `|`, found `+`
             1 | -3..0 => first_or.push(x),
             y @ (0..5 | 6) => or_two.push(y),
             y @ 0..const { 5 + 1 } => assert_eq!(y, 5),
diff --git a/tests/ui/half-open-range-patterns/range_pat_interactions1.stderr b/tests/ui/half-open-range-patterns/range_pat_interactions1.stderr
@@ -1,8 +1,8 @@
-error: expected one of `,`, `=>`, `if`, `|`, or `}`, found `+`
+error: expected one of `=>`, `if`, or `|`, found `+`
   --> $DIR/range_pat_interactions1.rs:19:17
    |
 LL |             0..5+1 => errors_only.push(x),
-   |                 ^ expected one of `,`, `=>`, `if`, `|`, or `}`
+   |                 ^ expected one of `=>`, `if`, or `|`
 
 error[E0408]: variable `n` is not bound in all patterns
   --> $DIR/range_pat_interactions1.rs:10:25
diff --git a/tests/ui/half-open-range-patterns/range_pat_interactions2.rs b/tests/ui/half-open-range-patterns/range_pat_interactions2.rs
@@ -9,7 +9,7 @@ fn main() {
         match x as i32 {
             0..=(5+1) => errors_only.push(x),
             //~^ error: inclusive range with no end
-            //~| error: expected one of `,`, `=>`, `if`, `|`, or `}`, found `(`
+            //~| error: expected one of `=>`, `if`, or `|`, found `(`
             1 | -3..0 => first_or.push(x),
             y @ (0..5 | 6) => or_two.push(y),
             y @ 0..const { 5 + 1 } => assert_eq!(y, 5),
diff --git a/tests/ui/half-open-range-patterns/range_pat_interactions2.stderr b/tests/ui/half-open-range-patterns/range_pat_interactions2.stderr
@@ -6,11 +6,11 @@ LL |             0..=(5+1) => errors_only.push(x),
    |
    = note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
 
-error: expected one of `,`, `=>`, `if`, `|`, or `}`, found `(`
+error: expected one of `=>`, `if`, or `|`, found `(`
   --> $DIR/range_pat_interactions2.rs:10:17
    |
 LL |             0..=(5+1) => errors_only.push(x),
-   |                 ^ expected one of `,`, `=>`, `if`, `|`, or `}`
+   |                 ^ expected one of `=>`, `if`, or `|`
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/parser/attribute/attr-stmt-expr-attr-bad.rs b/tests/ui/parser/attribute/attr-stmt-expr-attr-bad.rs
@@ -84,15 +84,15 @@ fn main() {}
 
 #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] 10 => () } }
 //~^ ERROR inclusive range with no end
-//~| ERROR expected one of `,`, `=>`, `if`, `|`, or `}`, found `#`
+//~| ERROR expected one of `=>`, `if`, or `|`, found `#`
 #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] -10 => () } }
 //~^ ERROR inclusive range with no end
-//~| ERROR expected one of `,`, `=>`, `if`, `|`, or `}`, found `#`
+//~| ERROR expected one of `=>`, `if`, or `|`, found `#`
 #[cfg(FALSE)] fn e() { match 0 { 0..=-#[attr] 10 => () } }
 //~^ ERROR unexpected token: `#`
 #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] FOO => () } }
 //~^ ERROR inclusive range with no end
-//~| ERROR expected one of `,`, `=>`, `if`, `|`, or `}`, found `#`
+//~| ERROR expected one of `=>`, `if`, or `|`, found `#`
 
 #[cfg(FALSE)] fn e() { let _ = x.#![attr]foo(); }
 //~^ ERROR unexpected token: `#`
diff --git a/tests/ui/parser/attribute/attr-stmt-expr-attr-bad.stderr b/tests/ui/parser/attribute/attr-stmt-expr-attr-bad.stderr
@@ -365,11 +365,11 @@ LL | #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] 10 => () } }
    |
    = note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
 
-error: expected one of `,`, `=>`, `if`, `|`, or `}`, found `#`
+error: expected one of `=>`, `if`, or `|`, found `#`
   --> $DIR/attr-stmt-expr-attr-bad.rs:85:38
    |
 LL | #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] 10 => () } }
-   |                                      ^ expected one of `,`, `=>`, `if`, `|`, or `}`
+   |                                      ^ expected one of `=>`, `if`, or `|`
 
 error[E0586]: inclusive range with no end
   --> $DIR/attr-stmt-expr-attr-bad.rs:88:35
@@ -379,11 +379,11 @@ LL | #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] -10 => () } }
    |
    = note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
 
-error: expected one of `,`, `=>`, `if`, `|`, or `}`, found `#`
+error: expected one of `=>`, `if`, or `|`, found `#`
   --> $DIR/attr-stmt-expr-attr-bad.rs:88:38
    |
 LL | #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] -10 => () } }
-   |                                      ^ expected one of `,`, `=>`, `if`, `|`, or `}`
+   |                                      ^ expected one of `=>`, `if`, or `|`
 
 error: unexpected token: `#`
   --> $DIR/attr-stmt-expr-attr-bad.rs:91:39
@@ -399,11 +399,11 @@ LL | #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] FOO => () } }
    |
    = note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
 
-error: expected one of `,`, `=>`, `if`, `|`, or `}`, found `#`
+error: expected one of `=>`, `if`, or `|`, found `#`
   --> $DIR/attr-stmt-expr-attr-bad.rs:93:38
    |
 LL | #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] FOO => () } }
-   |                                      ^ expected one of `,`, `=>`, `if`, `|`, or `}`
+   |                                      ^ expected one of `=>`, `if`, or `|`
 
 error: unexpected token: `#`
   --> $DIR/attr-stmt-expr-attr-bad.rs:97:34
diff --git a/tests/ui/parser/issues/issue-24375.rs b/tests/ui/parser/issues/issue-24375.rs
@@ -3,7 +3,7 @@ static tmp : [&'static str; 2]  = ["hello", "he"];
 fn main() {
     let z = "hello";
     match z {
-        tmp[0] => {} //~ ERROR expected one of `,`, `=>`, `@`, `if`, `|`, or `}`, found `[`
+        tmp[0] => {} //~ ERROR expected one of `=>`, `@`, `if`, or `|`, found `[`
         _ => {}
     }
 }
diff --git a/tests/ui/parser/issues/issue-24375.stderr b/tests/ui/parser/issues/issue-24375.stderr
@@ -1,8 +1,8 @@
-error: expected one of `,`, `=>`, `@`, `if`, `|`, or `}`, found `[`
+error: expected one of `=>`, `@`, `if`, or `|`, found `[`
   --> $DIR/issue-24375.rs:6:12
    |
 LL |         tmp[0] => {}
-   |            ^ expected one of `,`, `=>`, `@`, `if`, `|`, or `}`
+   |            ^ expected one of `=>`, `@`, `if`, or `|`
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/parser/match-arm-without-body.stderr b/tests/ui/parser/match-arm-without-body.stderr
@@ -1,8 +1,8 @@
-error: expected one of `,`, `=>`, `if`, `|`, or `}`, found reserved identifier `_`
+error: expected one of `=>`, `if`, or `|`, found reserved identifier `_`
   --> $DIR/match-arm-without-body.rs:13:9
    |
 LL |         Some(_)
-   |                - expected one of `,`, `=>`, `if`, `|`, or `}`
+   |                - expected one of `=>`, `if`, or `|`
 LL |         _ => {}
    |         ^ unexpected token
 
@@ -44,11 +44,11 @@ LL +
 LL ~         _ => {}
    |
 
-error: expected one of `,`, `.`, `=>`, `?`, `}`, or an operator, found reserved identifier `_`
+error: expected one of `.`, `=>`, `?`, or an operator, found reserved identifier `_`
   --> $DIR/match-arm-without-body.rs:36:9
    |
 LL |         Some(_) if true
-   |                        - expected one of `,`, `.`, `=>`, `?`, `}`, or an operator
+   |                        - expected one of `.`, `=>`, `?`, or an operator
 LL |         _ => {}
    |         ^ unexpected token
 
diff --git a/tests/ui/parser/pat-lt-bracket-1.rs b/tests/ui/parser/pat-lt-bracket-1.rs
@@ -1,7 +1,7 @@
 fn main() {
   match 42 {
     x < 7 => (),
-   //~^ error: expected one of `,`, `=>`, `@`, `if`, `|`, or `}`, found `<`
+   //~^ error: expected one of `=>`, `@`, `if`, or `|`, found `<`
     _ => ()
   }
 }
diff --git a/tests/ui/parser/pat-lt-bracket-1.stderr b/tests/ui/parser/pat-lt-bracket-1.stderr
@@ -1,8 +1,8 @@
-error: expected one of `,`, `=>`, `@`, `if`, `|`, or `}`, found `<`
+error: expected one of `=>`, `@`, `if`, or `|`, found `<`
   --> $DIR/pat-lt-bracket-1.rs:3:7
    |
 LL |     x < 7 => (),
-   |       ^ expected one of `,`, `=>`, `@`, `if`, `|`, or `}`
+   |       ^ expected one of `=>`, `@`, `if`, or `|`
 
 error: aborting due to 1 previous error
 

Original file line number	Diff line number	Diff line change
`@@ -17,7 +17,7 @@ fn main() {`
`17`	`17`	`}`
`18`	`18`	`match x as i32 {`
`19`	`19`	`0..5+1 => errors_only.push(x),`
`20`		- //~^ error: expected one of `,`, `=>`, `if`, `\|`, or `}`, found `+`
	`20`	+ //~^ error: expected one of `=>`, `if`, or `\|`, found `+`
`21`	`21`	`1 \| -3..0 => first_or.push(x),`
`22`	`22`	`y @ (0..5 \| 6) => or_two.push(y),`
`23`	`23`	`y @ 0..const { 5 + 1 } => assert_eq!(y, 5),`
Original file line number	Diff line number	Diff line change
`@@ -6,11 +6,11 @@ LL \| 0..=(5+1) => errors_only.push(x),`
`6`	`6`	`\|`
`7`	`7`	= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
`8`	`8`
`9`		-error: expected one of `,`, `=>`, `if`, `\|`, or `}`, found `(`
	`9`	+error: expected one of `=>`, `if`, or `\|`, found `(`
`10`	`10`	`--> $DIR/range_pat_interactions2.rs:10:17`
`11`	`11`	`\|`
`12`	`12`	`LL \| 0..=(5+1) => errors_only.push(x),`
`13`		- \| ^ expected one of `,`, `=>`, `if`, `\|`, or `}`
	`13`	+ \| ^ expected one of `=>`, `if`, or `\|`
`14`	`14`
`15`	`15`	`error: aborting due to 2 previous errors`
`16`	`16`
Original file line number	Diff line number	Diff line change
`@@ -365,11 +365,11 @@ LL \| #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] 10 => () } }`
`365`	`365`	`\|`
`366`	`366`	= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
`367`	`367`
`368`		-error: expected one of `,`, `=>`, `if`, `\|`, or `}`, found `#`
	`368`	+error: expected one of `=>`, `if`, or `\|`, found `#`
`369`	`369`	`--> $DIR/attr-stmt-expr-attr-bad.rs:85:38`
`370`	`370`	`\|`
`371`	`371`	`LL \| #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] 10 => () } }`
`372`		- \| ^ expected one of `,`, `=>`, `if`, `\|`, or `}`
	`372`	+ \| ^ expected one of `=>`, `if`, or `\|`
`373`	`373`
`374`	`374`	`error[E0586]: inclusive range with no end`
`375`	`375`	`--> $DIR/attr-stmt-expr-attr-bad.rs:88:35`
`@@ -379,11 +379,11 @@ LL \| #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] -10 => () } }`
`379`	`379`	`\|`
`380`	`380`	= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
`381`	`381`
`382`		-error: expected one of `,`, `=>`, `if`, `\|`, or `}`, found `#`
	`382`	+error: expected one of `=>`, `if`, or `\|`, found `#`
`383`	`383`	`--> $DIR/attr-stmt-expr-attr-bad.rs:88:38`
`384`	`384`	`\|`
`385`	`385`	`LL \| #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] -10 => () } }`
`386`		- \| ^ expected one of `,`, `=>`, `if`, `\|`, or `}`
	`386`	+ \| ^ expected one of `=>`, `if`, or `\|`
`387`	`387`
`388`	`388`	error: unexpected token: `#`
`389`	`389`	`--> $DIR/attr-stmt-expr-attr-bad.rs:91:39`
`@@ -399,11 +399,11 @@ LL \| #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] FOO => () } }`
`399`	`399`	`\|`
`400`	`400`	= note: inclusive ranges must be bounded at the end (`..=b` or `a..=b`)
`401`	`401`
`402`		-error: expected one of `,`, `=>`, `if`, `\|`, or `}`, found `#`
	`402`	+error: expected one of `=>`, `if`, or `\|`, found `#`
`403`	`403`	`--> $DIR/attr-stmt-expr-attr-bad.rs:93:38`
`404`	`404`	`\|`
`405`	`405`	`LL \| #[cfg(FALSE)] fn e() { match 0 { 0..=#[attr] FOO => () } }`
`406`		- \| ^ expected one of `,`, `=>`, `if`, `\|`, or `}`
	`406`	+ \| ^ expected one of `=>`, `if`, or `\|`
`407`	`407`
`408`	`408`	error: unexpected token: `#`
`409`	`409`	`--> $DIR/attr-stmt-expr-attr-bad.rs:97:34`
Original file line number	Diff line number	Diff line change
`@@ -3,7 +3,7 @@ static tmp : [&'static str; 2] = ["hello", "he"];`
`3`	`3`	`fn main() {`
`4`	`4`	`let z = "hello";`
`5`	`5`	`match z {`
`6`		- tmp[0] => {} //~ ERROR expected one of `,`, `=>`, `@`, `if`, `\|`, or `}`, found `[`
	`6`	+ tmp[0] => {} //~ ERROR expected one of `=>`, `@`, `if`, or `\|`, found `[`
`7`	`7`	`_ => {}`
`8`	`8`	`}`
`9`	`9`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,8 +1,8 @@`
`1`		-error: expected one of `,`, `=>`, `@`, `if`, `\|`, or `}`, found `[`
	`1`	+error: expected one of `=>`, `@`, `if`, or `\|`, found `[`
`2`	`2`	`--> $DIR/issue-24375.rs:6:12`
`3`	`3`	`\|`
`4`	`4`	`LL \| tmp[0] => {}`
`5`		- \| ^ expected one of `,`, `=>`, `@`, `if`, `\|`, or `}`
	`5`	+ \| ^ expected one of `=>`, `@`, `if`, or `\|`
`6`	`6`
`7`	`7`	`error: aborting due to 1 previous error`
`8`	`8`
Original file line number	Diff line number	Diff line change
`@@ -1,7 +1,7 @@`
`1`	`1`	`fn main() {`
`2`	`2`	`match 42 {`
`3`	`3`	`x < 7 => (),`
`4`		- //~^ error: expected one of `,`, `=>`, `@`, `if`, `\|`, or `}`, found `<`
	`4`	+ //~^ error: expected one of `=>`, `@`, `if`, or `\|`, found `<`
`5`	`5`	`_ => ()`
`6`	`6`	`}`
`7`	`7`	`}`