Rollup merge of rust-lang#114486 - Urgau:const-context-nan-suggestion-114471, r=compiler-errors

Avoid invalid NaN lint machine-applicable suggestion in const context

This PR removes the machine-applicable suggestion in const context for the `invalid_nan_comparision` lint ~~and replace it with a simple help~~.

Fixes rust-lang#114471

Author: matthiaskrgr

compiler/rustc_lint/src/lints.rs

@@ -1496,7 +1496,7 @@ pub enum InvalidNanComparisons {
     #[diag(lint_invalid_nan_comparisons_eq_ne)]
     EqNe {
         #[subdiagnostic]
-        suggestion: InvalidNanComparisonsSuggestion,
+        suggestion: Option<InvalidNanComparisonsSuggestion>,
     },
     #[diag(lint_invalid_nan_comparisons_lt_le_gt_ge)]
     LtLeGtGe,

compiler/rustc_lint/src/types.rs

@@ -572,32 +572,36 @@ 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 {
-        let suggestion =
+        // 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) {
+                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(e, l, r, |l_span, r_span| InvalidNanComparisonsSuggestion::Spanful {
+            eq_ne(cx, 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(e, l, r, |l_span, r_span| InvalidNanComparisonsSuggestion::Spanful {
+            eq_ne(cx, 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/lint/invalid-nan-comparison.stderr

@@ -5,11 +5,6 @@ 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