Revert "Avoid invalid NaN lint machine-applicable suggestion in const…

… context"

Reverts PR #114486 (commit 1305a43)

compiler/rustc_lint/src/lints.rs

@@ -1739,7 +1739,7 @@ pub(crate) enum InvalidNanComparisons {
     #[diag(lint_invalid_nan_comparisons_eq_ne)]
     EqNe {
         #[subdiagnostic]
-        suggestion: Option<InvalidNanComparisonsSuggestion>,
+        suggestion: InvalidNanComparisonsSuggestion,
     },
     #[diag(lint_invalid_nan_comparisons_lt_le_gt_ge)]
     LtLeGtGe,

compiler/rustc_lint/src/types.rs

@@ -605,36 +605,32 @@ fn lint_nan<'tcx>(
     }
 
     fn eq_ne(
-        cx: &LateContext<'_>,
         e: &hir::Expr<'_>,
         l: &hir::Expr<'_>,
         r: &hir::Expr<'_>,
         f: impl FnOnce(Span, Span) -> InvalidNanComparisonsSuggestion,
     ) -> InvalidNanComparisons {
-        // FIXME(#72505): This suggestion can be restored if `f{32,64}::is_nan` is made const.
-        let suggestion = (!cx.tcx.hir().is_inside_const_context(e.hir_id)).then(|| {
-            if let Some(l_span) = l.span.find_ancestor_inside(e.span)
-                && let Some(r_span) = r.span.find_ancestor_inside(e.span)
-            {
-                f(l_span, r_span)
-            } else {
-                InvalidNanComparisonsSuggestion::Spanless
-            }
-        });
+        let suggestion = if let Some(l_span) = l.span.find_ancestor_inside(e.span)
+            && let Some(r_span) = r.span.find_ancestor_inside(e.span)
+        {
+            f(l_span, r_span)
+        } else {
+            InvalidNanComparisonsSuggestion::Spanless
+        };
 
         InvalidNanComparisons::EqNe { suggestion }
     }
 
     let lint = match binop.node {
         hir::BinOpKind::Eq | hir::BinOpKind::Ne if is_nan(cx, l) => {
-            eq_ne(cx, e, l, r, |l_span, r_span| InvalidNanComparisonsSuggestion::Spanful {
+            eq_ne(e, l, r, |l_span, r_span| InvalidNanComparisonsSuggestion::Spanful {
                 nan_plus_binop: l_span.until(r_span),
                 float: r_span.shrink_to_hi(),
                 neg: (binop.node == hir::BinOpKind::Ne).then(|| r_span.shrink_to_lo()),
             })
         }
         hir::BinOpKind::Eq | hir::BinOpKind::Ne if is_nan(cx, r) => {
-            eq_ne(cx, e, l, r, |l_span, r_span| InvalidNanComparisonsSuggestion::Spanful {
+            eq_ne(e, l, r, |l_span, r_span| InvalidNanComparisonsSuggestion::Spanful {
                 nan_plus_binop: l_span.shrink_to_hi().to(r_span),
                 float: l_span.shrink_to_hi(),
                 neg: (binop.node == hir::BinOpKind::Ne).then(|| l_span.shrink_to_lo()),

tests/ui/float/classify-runtime-const.rs

@@ -6,7 +6,6 @@
 
 #![feature(f16_const)]
 #![feature(f128_const)]
-#![feature(const_float_classify)]
 
 use std::hint::black_box;
 use std::num::FpCategory::*;

tests/ui/float/conv-bits-runtime-const.rs

@@ -3,7 +3,6 @@
 
 // This tests the float classification functions, for regular runtime code and for const evaluation.
 
-#![feature(const_float_classify)]
 #![feature(f16)]
 #![feature(f128)]
 #![feature(f16_const)]

tests/ui/lint/invalid-nan-comparison.stderr

@@ -5,6 +5,11 @@ LL | const TEST: bool = 5f32 == f32::NAN;
    |                    ^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(invalid_nan_comparisons)]` on by default
+help: use `f32::is_nan()` or `f64::is_nan()` instead
+   |
+LL - const TEST: bool = 5f32 == f32::NAN;
+LL + const TEST: bool = 5f32.is_nan();
+   |
 
 warning: incorrect NaN comparison, NaN cannot be directly compared to itself
   --> $DIR/invalid-nan-comparison.rs:14:5