Only suggest the fix for empty patterns

rust-lang · Aug 19, 2024 · a0ffb44 · a0ffb44
1 parent 8190fd1
commit a0ffb44
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Showing 37 changed files with 137 additions and 651 deletions.
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -921,7 +921,7 @@ fn report_unreachable_pattern<'p, 'tcx>(
     hir_id: HirId,
     pat: &DeconstructedPat<'p, 'tcx>,
     explanation: &RedundancyExplanation<'p, 'tcx>,
-    suggest_remove: Option<Span>,
+    whole_arm_span: Option<Span>,
 ) {
     let pat_span = pat.data().span;
     let mut lint = UnreachablePattern {
@@ -930,12 +930,13 @@ fn report_unreachable_pattern<'p, 'tcx>(
         covered_by_catchall: None,
         covered_by_one: None,
         covered_by_many: None,
-        suggest_remove,
+        suggest_remove: None,
     };
     match explanation.covered_by.as_slice() {
         [] => {
             // Empty pattern; we report the uninhabited type that caused the emptiness.
             lint.span = None; // Don't label the pattern itself
+            lint.suggest_remove = whole_arm_span; // Suggest to remove the match arm
             pat.walk(&mut |subpat| {
                 let ty = **subpat.ty();
                 if cx.is_uninhabited(ty) {
@@ -981,7 +982,7 @@ fn report_arm_reachability<'p, 'tcx>(
         if let Usefulness::Redundant(explanation) = is_useful {
             let hir_id = arm.arm_data;
             let arm_span = cx.tcx.hir().span(hir_id);
-            let suggest_remove = if is_match_arm {
+            let whole_arm_span = if is_match_arm {
                 // If the arm is followed by a comma, extend the span to include it.
                 let with_whitespace = sm.span_extend_while_whitespace(arm_span);
                 if let Some(comma) = sm.span_look_ahead(with_whitespace, ",", Some(1)) {
@@ -992,7 +993,7 @@ fn report_arm_reachability<'p, 'tcx>(
             } else {
                 None
             };
-            report_unreachable_pattern(cx, hir_id, arm.pat, explanation, suggest_remove)
+            report_unreachable_pattern(cx, hir_id, arm.pat, explanation, whole_arm_span)
         }
     }
 }

diff --git a/tests/ui/consts/packed_pattern.stderr b/tests/ui/consts/packed_pattern.stderr
@@ -4,10 +4,7 @@ warning: unreachable pattern
 LL |         Foo { field: (5, 6, 7, 8) } => {},
    |         --------------------------- matches all the values already
 LL |         FOO => unreachable!(),
-   |         ^^^-------------------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^ unreachable pattern
    |
    = note: `#[warn(unreachable_patterns)]` on by default
 

diff --git a/tests/ui/consts/packed_pattern2.stderr b/tests/ui/consts/packed_pattern2.stderr
@@ -4,10 +4,7 @@ warning: unreachable pattern
 LL |         Bar { a: Foo { field: (5, 6) } } => {},
    |         -------------------------------- matches all the values already
 LL |         FOO => unreachable!(),
-   |         ^^^-------------------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^ unreachable pattern
    |
    = note: `#[warn(unreachable_patterns)]` on by default
 

diff --git a/tests/ui/error-codes/E0001.stderr b/tests/ui/error-codes/E0001.stderr
@@ -2,10 +2,7 @@ error: unreachable pattern
   --> $DIR/E0001.rs:8:9
    |
 LL |         _ => {/* ... */}
-   |         ^---------------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
    |
 note: these patterns collectively make the last one unreachable
   --> $DIR/E0001.rs:8:9

diff --git a/tests/ui/lint/issue-30302.stderr b/tests/ui/lint/issue-30302.stderr
@@ -13,10 +13,7 @@ LL |         Nil => true,
    |         --- matches any value
 LL |
 LL |         _ => false
-   |         ^---------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
    |
 note: the lint level is defined here
   --> $DIR/issue-30302.rs:4:9

diff --git a/tests/ui/or-patterns/exhaustiveness-unreachable-pattern.stderr b/tests/ui/or-patterns/exhaustiveness-unreachable-pattern.stderr
@@ -4,10 +4,7 @@ error: unreachable pattern
 LL |         (1 | 2,) => {}
    |         -------- matches all the values already
 LL |         (1,) => {}
-   |         ^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^ unreachable pattern
    |
 note: the lint level is defined here
   --> $DIR/exhaustiveness-unreachable-pattern.rs:1:9
@@ -21,19 +18,13 @@ error: unreachable pattern
 LL |         (1 | 2,) => {}
    |         -------- matches all the values already
 LL |         (2,) => {}
-   |         ^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:19:9
    |
 LL |         (1 | 2,) => {}
-   |         ^^^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^^^ unreachable pattern
    |
 note: these patterns collectively make the last one unreachable
   --> $DIR/exhaustiveness-unreachable-pattern.rs:19:9
@@ -51,10 +42,7 @@ error: unreachable pattern
 LL |         (1 | 2, 3 | 4) => {}
    |         -------------- matches all the values already
 LL |         (1, 3) => {}
-   |         ^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:25:9
@@ -63,10 +51,7 @@ LL |         (1 | 2, 3 | 4) => {}
    |         -------------- matches all the values already
 LL |         (1, 3) => {}
 LL |         (1, 4) => {}
-   |         ^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:26:9
@@ -75,10 +60,7 @@ LL |         (1 | 2, 3 | 4) => {}
    |         -------------- matches all the values already
 ...
 LL |         (2, 4) => {}
-   |         ^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:27:9
@@ -87,19 +69,13 @@ LL |         (1 | 2, 3 | 4) => {}
    |         -------------- matches all the values already
 ...
 LL |         (2 | 1, 4) => {}
-   |         ^^^^^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:29:9
    |
 LL |         (1, 4 | 5) => {}
-   |         ^^^^^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^^^^^ unreachable pattern
    |
 note: these patterns collectively make the last one unreachable
   --> $DIR/exhaustiveness-unreachable-pattern.rs:29:9
@@ -126,10 +102,7 @@ error: unreachable pattern
 LL |         (None | Some(1 | 2),) => {}
    |         --------------------- matches all the values already
 LL |         (Some(1),) => {}
-   |         ^^^^^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:43:9
@@ -138,21 +111,15 @@ LL |         (None | Some(1 | 2),) => {}
    |         --------------------- matches all the values already
 LL |         (Some(1),) => {}
 LL |         (None,) => {}
-   |         ^^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:48:9
    |
 LL |         ((1 | 2,) | (3 | 4,),) => {}
    |         ---------------------- matches all the values already
 LL |         ((1..=4,),) => {}
-   |         ^^^^^^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/exhaustiveness-unreachable-pattern.rs:53:14

diff --git a/tests/ui/pattern/issue-14221.stderr b/tests/ui/pattern/issue-14221.stderr
@@ -19,10 +19,7 @@ LL |             A => "A",
    |             - matches any value
 LL |
 LL |             B => "B",
-   |             ^--------
-   |             |
-   |             unreachable pattern
-   |             help: remove the match arm
+   |             ^ unreachable pattern
    |
 note: the lint level is defined here
   --> $DIR/issue-14221.rs:1:9

diff --git a/tests/ui/pattern/usefulness/consts-opaque.stderr b/tests/ui/pattern/usefulness/consts-opaque.stderr
@@ -52,10 +52,7 @@ error: unreachable pattern
 LL |         Bar => {}
    |         --- matches any value
 LL |         BAR => {}
-   |         ^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^ unreachable pattern
    |
 note: the lint level is defined here
   --> $DIR/consts-opaque.rs:6:9
@@ -70,21 +67,15 @@ LL |         Bar => {}
    |         --- matches any value
 ...
 LL |         _ => {}
-   |         ^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:56:9
    |
 LL |         BAR => {}
    |         --- matches any value
 LL |         Bar => {}
-   |         ^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:58:9
@@ -93,21 +84,15 @@ LL |         BAR => {}
    |         --- matches any value
 ...
 LL |         _ => {}
-   |         ^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:64:9
    |
 LL |         BAR => {}
    |         --- matches any value
 LL |         BAR => {} // should not be emitting unreachable warning
-   |         ^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:66:9
@@ -116,41 +101,29 @@ LL |         BAR => {}
    |         --- matches any value
 ...
 LL |         _ => {} // should not be emitting unreachable warning
-   |         ^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:72:9
    |
 LL |         BAZ => {}
    |         --- matches all the values already
 LL |         Baz::Baz1 => {} // should not be emitting unreachable warning
-   |         ^^^^^^^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:79:9
    |
 LL |         Baz::Baz1 => {}
    |         --------- matches all the values already
 LL |         BAZ => {}
-   |         ^^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:87:9
    |
 LL |         _ => {} // should not be emitting unreachable warning
-   |         ^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
    |
 note: these patterns collectively make the last one unreachable
   --> $DIR/consts-opaque.rs:87:9

diff --git a/tests/ui/pattern/usefulness/empty-types.exhaustive_patterns.stderr b/tests/ui/pattern/usefulness/empty-types.exhaustive_patterns.stderr
@@ -245,10 +245,7 @@ error: unreachable pattern
 LL |             None => {}
    |             ---- matches all the values already
 LL |             _ => {}
-   |             ^------
-   |             |
-   |             unreachable pattern
-   |             help: remove the match arm
+   |             ^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:199:13
@@ -445,10 +442,7 @@ error: unreachable pattern
 LL |         [] => {}
    |         -- matches all the values already
 LL |         _ => {}
-   |         ^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
 
 error[E0004]: non-exhaustive patterns: `[]` not covered
   --> $DIR/empty-types.rs:397:11
@@ -491,10 +485,7 @@ LL |         None => {}
    |         ---- matches all the values already
 LL |         // !useful, !reachable
 LL |         _ => {}
-   |         ^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:431:9
@@ -503,10 +494,7 @@ LL |         None => {}
    |         ---- matches all the values already
 LL |         // !useful, !reachable
 LL |         _a => {}
-   |         ^^------
-   |         |
-   |         unreachable pattern
-   |         help: remove the match arm
+   |         ^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/empty-types.rs:603:9