Add diagnostic items for f32::NAN and f64::NAN

Author: Urgau

compiler/rustc_span/src/symbol.rs

@@ -701,7 +701,9 @@ symbols! {
         f,
         f16c_target_feature,
         f32,
+        f32_nan,
         f64,
+        f64_nan,
         fabsf32,
         fabsf64,
         fadd_fast,

library/core/src/num/f32.rs

@@ -403,6 +403,7 @@ impl f32 {
     /// and the stability of its representation over Rust versions
     /// and target platforms isn't guaranteed.
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
+    #[rustc_diagnostic_item = "f32_nan"]
     pub const NAN: f32 = 0.0_f32 / 0.0_f32;
     /// Infinity (∞).
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]

library/core/src/num/f64.rs

@@ -401,6 +401,7 @@ impl f64 {
     /// This constant isn't guaranteed to equal to any specific NaN bitpattern,
     /// and the stability of its representation over Rust versions
     /// and target platforms isn't guaranteed.
+    #[rustc_diagnostic_item = "f64_nan"]
     #[stable(feature = "assoc_int_consts", since = "1.43.0")]
     pub const NAN: f64 = 0.0_f64 / 0.0_f64;
     /// Infinity (∞).