remove illegal_floating_point_literal_pattern lint

Author: RalfJung

compiler/rustc_lint/src/lib.rs

@@ -516,6 +516,10 @@ fn register_builtins(store: &mut LintStore) {
         "converted into hard error, see PR #118649 \
          <https://github.com/rust-lang/rust/pull/118649> for more information",
     );
+    store.register_removed(
+        "illegal_floating_point_literal_pattern",
+        "no longer a warning, float patterns behave the same as `==`",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {

compiler/rustc_lint_defs/src/builtin.rs

@@ -45,7 +45,6 @@ declare_lint_pass! {
         FUZZY_PROVENANCE_CASTS,
         HIDDEN_GLOB_REEXPORTS,
         ILL_FORMED_ATTRIBUTE_INPUT,
-        ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
         INCOMPLETE_INCLUDE,
         INDIRECT_STRUCTURAL_MATCH,
         INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
@@ -1873,55 +1872,6 @@ declare_lint! {
      };
 }
 
-declare_lint! {
-    /// The `illegal_floating_point_literal_pattern` lint detects
-    /// floating-point literals used in patterns.
-    ///
-    /// ### Example
-    ///
-    /// ```rust
-    /// let x = 42.0;
-    ///
-    /// match x {
-    ///     5.0 => {}
-    ///     _ => {}
-    /// }
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// Previous versions of the compiler accepted floating-point literals in
-    /// patterns, but it was later determined this was a mistake. The
-    /// semantics of comparing floating-point values may not be clear in a
-    /// pattern when contrasted with "structural equality". Typically you can
-    /// work around this by using a [match guard], such as:
-    ///
-    /// ```rust
-    /// # let x = 42.0;
-    ///
-    /// match x {
-    ///     y if y == 5.0 => {}
-    ///     _ => {}
-    /// }
-    /// ```
-    ///
-    /// This is a [future-incompatible] lint to transition this to a hard
-    /// error in the future. See [issue #41620] for more details.
-    ///
-    /// [issue #41620]: https://github.com/rust-lang/rust/issues/41620
-    /// [match guard]: https://doc.rust-lang.org/reference/expressions/match-expr.html#match-guards
-    /// [future-incompatible]: ../index.md#future-incompatible-lints
-    pub ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
-    Warn,
-    "floating-point literals cannot be used in patterns",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
-        reference: "issue #41620 <https://github.com/rust-lang/rust/issues/41620>",
-    };
-}
-
 declare_lint! {
     /// The `unstable_name_collisions` lint detects that you have used a name
     /// that the standard library plans to add in the future.

compiler/rustc_mir_build/messages.ftl

@@ -107,8 +107,6 @@ mir_build_extern_static_requires_unsafe_unsafe_op_in_unsafe_fn_allowed =
     .note = extern statics are not controlled by the Rust type system: invalid data, aliasing violations or data races will cause undefined behavior
     .label = use of extern static
 
-mir_build_float_pattern = floating-point types cannot be used in patterns
-
 mir_build_indirect_structural_match =
     to use a constant of type `{$non_sm_ty}` in a pattern, `{$non_sm_ty}` must be annotated with `#[derive(PartialEq)]`
 

compiler/rustc_mir_build/src/errors.rs

@@ -789,10 +789,6 @@ pub struct NaNPattern {
     pub span: Span,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(mir_build_float_pattern)]
-pub struct FloatPattern;
-
 #[derive(LintDiagnostic)]
 #[diag(mir_build_pointer_pattern)]
 pub struct PointerPattern;

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -17,7 +17,7 @@ use std::cell::Cell;
 
 use super::PatCtxt;
 use crate::errors::{
-    FloatPattern, IndirectStructuralMatch, InvalidPattern, NaNPattern, NonPartialEqMatch,
+    IndirectStructuralMatch, InvalidPattern, NaNPattern, NonPartialEqMatch,
     NontrivialStructuralMatch, PointerPattern, TypeNotStructural, UnionPattern, UnsizedPattern,
 };
 
@@ -488,16 +488,10 @@ impl<'tcx> ConstToPat<'tcx> {
                     // Also see <https://github.com/rust-lang/rfcs/pull/3535>.
                     let e = tcx.dcx().emit_err(NaNPattern { span });
                     self.saw_const_match_error.set(Some(e));
+                    return Err(FallbackToOpaqueConst);
                 } else {
-                    self.saw_const_match_lint.set(true);
-                    tcx.emit_node_span_lint(
-                        lint::builtin::ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
-                        id,
-                        span,
-                        FloatPattern,
-                    );
+                    PatKind::Constant { value: mir::Const::Ty(ty::Const::new_value(tcx, cv, ty)) }
                 }
-                return Err(FallbackToOpaqueConst);
             }
             ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::RawPtr(..) => {
                 // The raw pointers we see here have been "vetted" by valtree construction to be

src/tools/clippy/tests/ui/expect_tool_lint_rfc_2383.rs

@@ -20,12 +20,8 @@ mod rustc_ok {
     pub fn rustc_lints() {
         let x = 42.0;
 
-        #[expect(illegal_floating_point_literal_pattern)]
-        match x {
-            5.0 => {}
-            6.0 => {}
-            _ => {}
-        }
+        #[expect(invalid_nan_comparisons)]
+        let _b = x == f32::NAN;
     }
 }
 
@@ -38,13 +34,9 @@ mod rustc_warn {
     pub fn rustc_lints() {
         let x = 42;
 
-        #[expect(illegal_floating_point_literal_pattern)]
+        #[expect(invalid_nan_comparisons)]
         //~^ ERROR: this lint expectation is unfulfilled
-        match x {
-            5 => {}
-            6 => {}
-            _ => {}
-        }
+        let _b = x == 5;
     }
 }
 

src/tools/clippy/tests/ui/expect_tool_lint_rfc_2383.stderr

@@ -1,5 +1,5 @@
 error: this lint expectation is unfulfilled
-  --> $DIR/expect_tool_lint_rfc_2383.rs:35:14
+  --> $DIR/expect_tool_lint_rfc_2383.rs:31:14
    |
 LL |     #[expect(dead_code)]
    |              ^^^^^^^^^
@@ -8,31 +8,31 @@ LL |     #[expect(dead_code)]
    = help: to override `-D warnings` add `#[allow(unfulfilled_lint_expectations)]`
 
 error: this lint expectation is unfulfilled
-  --> $DIR/expect_tool_lint_rfc_2383.rs:41:18
+  --> $DIR/expect_tool_lint_rfc_2383.rs:37:18
    |
-LL |         #[expect(illegal_floating_point_literal_pattern)]
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |         #[expect(invalid_nan_comparisons)]
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this lint expectation is unfulfilled
-  --> $DIR/expect_tool_lint_rfc_2383.rs:116:14
+  --> $DIR/expect_tool_lint_rfc_2383.rs:108:14
    |
 LL |     #[expect(clippy::almost_swapped)]
    |              ^^^^^^^^^^^^^^^^^^^^^^
 
 error: this lint expectation is unfulfilled
-  --> $DIR/expect_tool_lint_rfc_2383.rs:124:14
+  --> $DIR/expect_tool_lint_rfc_2383.rs:116:14
    |
 LL |     #[expect(clippy::bytes_nth)]
    |              ^^^^^^^^^^^^^^^^^
 
 error: this lint expectation is unfulfilled
-  --> $DIR/expect_tool_lint_rfc_2383.rs:130:14
+  --> $DIR/expect_tool_lint_rfc_2383.rs:122:14
    |
 LL |     #[expect(clippy::if_same_then_else)]
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this lint expectation is unfulfilled
-  --> $DIR/expect_tool_lint_rfc_2383.rs:136:14
+  --> $DIR/expect_tool_lint_rfc_2383.rs:128:14
    |
 LL |     #[expect(clippy::overly_complex_bool_expr)]
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/rustdoc-ui/lints/expect-tool-lint-rfc-2383.rs

@@ -24,10 +24,9 @@ mod rustc_ok {
     pub fn rustc_lints() {
         let x = 42.0;
 
-        #[expect(illegal_floating_point_literal_pattern)]
+        #[expect(invalid_nan_comparisons)]
         match x {
-            5.0 => {}
-            6.0 => {}
+            f32::NAN => {}
             _ => {}
         }
     }
@@ -40,7 +39,7 @@ mod rustc_warn {
     pub fn rustc_lints() {
         let x = 42;
 
-        #[expect(illegal_floating_point_literal_pattern)]
+        #[expect(invalid_nan_comparisons)]
         match x {
             5 => {}
             6 => {}

tests/rustdoc-ui/lints/expect-tool-lint-rfc-2383.stderr

@@ -7,19 +7,19 @@ LL | #![expect(rustdoc::missing_crate_level_docs)]
    = note: `#[warn(unfulfilled_lint_expectations)]` on by default
 
 warning: this lint expectation is unfulfilled
-  --> $DIR/expect-tool-lint-rfc-2383.rs:71:14
+  --> $DIR/expect-tool-lint-rfc-2383.rs:70:14
    |
 LL |     #[expect(rustdoc::broken_intra_doc_links)]
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: this lint expectation is unfulfilled
-  --> $DIR/expect-tool-lint-rfc-2383.rs:76:14
+  --> $DIR/expect-tool-lint-rfc-2383.rs:75:14
    |
 LL |     #[expect(rustdoc::invalid_html_tags)]
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: this lint expectation is unfulfilled
-  --> $DIR/expect-tool-lint-rfc-2383.rs:81:14
+  --> $DIR/expect-tool-lint-rfc-2383.rs:80:14
    |
 LL |     #[expect(rustdoc::bare_urls)]
    |              ^^^^^^^^^^^^^^^^^^

tests/ui/array-slice-vec/vec-matching-autoslice.rs

@@ -1,5 +1,4 @@
 // run-pass
-#![allow(illegal_floating_point_literal_pattern)] // FIXME #41620
 
 pub fn main() {
     let x = [1, 2, 3];