glsl-in: Add tests for constants NaN handling

src/front/glsl/constants.rs

@@ -234,9 +234,7 @@ impl<'a> ConstantSolver<'a> {
  ScalarValue::Float(a),
  ScalarValue::Float(b),
  ScalarValue::Float(c),
- ) => {
- ScalarValue::Float(glsl_float_min(glsl_float_max(a, b), c))
- }
+ ) => ScalarValue::Float(glsl_float_clamp(a, b, c)),
  _ => return Err(ConstantSolvingError::InvalidMathArg),
  },
  width,
@@ -599,6 +597,15 @@ fn glsl_float_min(x: f64, y: f64) -> f64 {
  }
 }
 
+/// Helper function to implement the GLSL `clamp` function for floats.
+///
+/// While Rust does provide a `f64::clamp` method, it requires a version of rust
+/// above our MSRV and it also panics if either `min` or `max` are `NaN`s which
+/// is not the behavior specified by the glsl specification.
+fn glsl_float_clamp(value: f64, min: f64, max: f64) -> f64 {
+ glsl_float_min(glsl_float_max(value, min), max)
+}
+
 #[cfg(test)]
 mod tests {
  use std::vec;
@@ -610,6 +617,19 @@ mod tests {
 
  use super::ConstantSolver;
 
+ #[test]
+ fn nan_handling() {
+ assert!(super::glsl_float_max(f64::NAN, 2.0).is_nan());
+ assert!(!super::glsl_float_max(2.0, f64::NAN).is_nan());
+
+ assert!(super::glsl_float_min(f64::NAN, 2.0).is_nan());
+ assert!(!super::glsl_float_min(2.0, f64::NAN).is_nan());
+
+ assert!(super::glsl_float_clamp(f64::NAN, 1.0, 2.0).is_nan());
+ assert!(!super::glsl_float_clamp(1.0, f64::NAN, 2.0).is_nan());
+ assert!(!super::glsl_float_clamp(1.0, 2.0, f64::NAN).is_nan());
+ }
+
  #[test]
  fn unary_op() {
  let mut types = UniqueArena::new();