Define UB in float-to-int casts to saturate

- Round to zero, and representable values cast directly.
- `NaN` goes to 0
- Values beyond the limits of the type are saturated to the "nearest value"
  (essentially rounding to zero, in some sense) in the integral type, so e.g.
  `f32::INFINITY` would go to `{u,i}N::MAX.`

1 files changed, 1 insertions, 1 deletions

diff --git a/src/librustc_codegen_ssa/mir/rvalue.rs b/src/librustc_codegen_ssa/mir/rvalue.rs
index 19a0138d9cb..bb532abd84b 100644
--- a/src/librustc_codegen_ssa/mir/rvalue.rs
+++ b/src/librustc_codegen_ssa/mir/rvalue.rs
@@ -768,7 +768,7 @@ fn cast_float_to_int<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 ) -> Bx::Value {
     let fptosui_result = if signed { bx.fptosi(x, int_ty) } else { bx.fptoui(x, int_ty) };
 
-    if !bx.cx().sess().opts.debugging_opts.saturating_float_casts {
+    if let Some(false) = bx.cx().sess().opts.debugging_opts.saturating_float_casts {
         return fptosui_result;
     }