float: Add `f16` to `test-float-parse`

This requires a fix to the subnormal test to cap the maximum allowed
value within the maximum mantissa.

4 files changed, 25 insertions, 3 deletions

diff --git a/src/etc/test-float-parse/Cargo.toml b/src/etc/test-float-parse/Cargo.toml
index 8a9c5322ef7..e407e322f9e 100644
--- a/src/etc/test-float-parse/Cargo.toml
+++ b/src/etc/test-float-parse/Cargo.toml
@@ -13,3 +13,10 @@ rayon = "1"
 
 [lib]
 name = "test_float_parse"
+
+[lints.rust.unexpected_cfgs]
+level = "warn"
+check-cfg = [
+    # Internal features aren't marked known config by default
+    'cfg(target_has_reliable_f16)',
+]
diff --git a/src/etc/test-float-parse/src/gen_/subnorm.rs b/src/etc/test-float-parse/src/gen_/subnorm.rs
index 4fe3b90a3dd..654f324b9b0 100644
--- a/src/etc/test-float-parse/src/gen_/subnorm.rs
+++ b/src/etc/test-float-parse/src/gen_/subnorm.rs
@@ -1,4 +1,3 @@
-use std::cmp::min;
 use std::fmt::Write;
 use std::ops::RangeInclusive;
 
@@ -83,7 +82,13 @@ where
     }
 
     fn new() -> Self {
-        Self { iter: F::Int::ZERO..=min(F::Int::ONE << 22, F::MAN_BITS.try_into().unwrap()) }
+        let upper_lim = if F::MAN_BITS >= 22 {
+            F::Int::ONE << 22
+        } else {
+            (F::Int::ONE << F::MAN_BITS) - F::Int::ONE
+        };
+
+        Self { iter: F::Int::ZERO..=upper_lim }
     }
 
     fn write_string(s: &mut String, ctx: Self::WriteCtx) {
diff --git a/src/etc/test-float-parse/src/lib.rs b/src/etc/test-float-parse/src/lib.rs
index 3c3ef5802b6..0bd4878f9a6 100644
--- a/src/etc/test-float-parse/src/lib.rs
+++ b/src/etc/test-float-parse/src/lib.rs
@@ -1,3 +1,7 @@
+#![feature(f16)]
+#![feature(cfg_target_has_reliable_f16_f128)]
+#![expect(internal_features)] // reliable_f16_f128
+
 mod traits;
 mod ui;
 mod validate;
@@ -114,6 +118,9 @@ pub fn register_tests(cfg: &Config) -> Vec<TestInfo> {
     let mut tests = Vec::new();
 
     // Register normal generators for all floats.
+
+    #[cfg(target_has_reliable_f16)]
+    register_float::<f16>(&mut tests, cfg);
     register_float::<f32>(&mut tests, cfg);
     register_float::<f64>(&mut tests, cfg);
 
diff --git a/src/etc/test-float-parse/src/traits.rs b/src/etc/test-float-parse/src/traits.rs
index 57e702b7d09..65a8721bfa5 100644
--- a/src/etc/test-float-parse/src/traits.rs
+++ b/src/etc/test-float-parse/src/traits.rs
@@ -98,7 +98,7 @@ macro_rules! impl_int {
     }
 }
 
-impl_int!(u32, i32; u64, i64);
+impl_int!(u16, i16; u32, i32; u64, i64);
 
 /// Floating point types.
 pub trait Float:
@@ -170,6 +170,9 @@ macro_rules! impl_float {
 
 impl_float!(f32, u32; f64, u64);
 
+#[cfg(target_has_reliable_f16)]
+impl_float!(f16, u16);
+
 /// A test generator. Should provide an iterator that produces unique patterns to parse.
 ///
 /// The iterator needs to provide a `WriteCtx` (could be anything), which is then used to