fix(naga): don't panic on f16s in pipeline constants (#7801)

CHANGELOG.md

@@ -80,6 +80,7 @@ Bottom level categories:
 - Generate vectorized code for `[un]pack4x{I,U}8[Clamp]` on SPIR-V and MSL 2.1+. By @robamler in [#7664](https://github.com/gfx-rs/wgpu/pull/7664).
 - Fix typing for `select`, which had issues particularly with a lack of automatic type conversion. By @ErichDonGubler in [#7572](https://github.com/gfx-rs/wgpu/pull/7572).
 - Allow scalars as the first argument of the `distance` built-in function. By @bernhl in [#7530](https://github.com/gfx-rs/wgpu/pull/7530).
+- Don't panic when handling `f16` for pipeline constants, i.e., `override`s in WGSL. By @ErichDonGubler in [#7801](https://github.com/gfx-rs/wgpu/pull/7801).
 
 #### DX12
 
@@ -128,7 +129,6 @@ Bottom level categories:
 
 - Added initial `no_std` support to `wgpu-hal`. By @bushrat011899 in [#7599](https://github.com/gfx-rs/wgpu/pull/7599)
 
-
 ### Documentation
 
 #### General

cts_runner/test.lst

@@ -27,6 +27,7 @@ webgpu:api,operation,uncapturederror:iff_uncaptured:*
 // There are also two unimplemented SKIPs in uncapturederror not enumerated here.
 webgpu:api,validation,encoding,queries,general:occlusion_query,query_type:*
 webgpu:shader,execution,flow_control,return:*
+webgpu:shader,validation,expression,call,builtin,max:values:*
 webgpu:shader,validation,statement,statement_behavior:invalid_statements:body="break"
 webgpu:shader,validation,statement,statement_behavior:invalid_statements:body="break_if"
 webgpu:shader,validation,statement,statement_behavior:invalid_statements:body="continue"

naga/src/back/pipeline_constants.rs

@@ -945,6 +945,19 @@ fn map_value_to_literal(value: f64, scalar: Scalar) -> Result<Literal, PipelineC
             let value = value as u32;
             Ok(Literal::U32(value))
         }
+        Scalar::F16 => {
+            // https://webidl.spec.whatwg.org/#js-float
+            if !value.is_finite() {
+                return Err(PipelineConstantError::SrcNeedsToBeFinite);
+            }
+
+            let value = half::f16::from_f64(value);
+            if !value.is_finite() {
+                return Err(PipelineConstantError::DstRangeTooSmall);
+            }
+
+            Ok(Literal::F16(value))
+        }
         Scalar::F32 => {
             // https://webidl.spec.whatwg.org/#js-float
             if !value.is_finite() {
@@ -966,7 +979,10 @@ fn map_value_to_literal(value: f64, scalar: Scalar) -> Result<Literal, PipelineC
 
             Ok(Literal::F64(value))
         }
-        _ => unreachable!(),
+        Scalar::ABSTRACT_FLOAT | Scalar::ABSTRACT_INT => {
+            unreachable!("abstract values should not be validated out of override processing")
+        }
+        _ => unreachable!("unrecognized scalar type for override"),
     }
 }