derivative: fix missing safety doc

Author: Firestar99

Diff for: crates/spirv-std/src/arch/derivative.rs

@@ -19,6 +19,9 @@ macro_rules! deriv_fn {
 }
 
 /// Types that can be derived by partial derivatives
+///
+/// # Safety
+/// Result Type must be a scalar or vector of floating-point type using the IEEE 754 encoding. The component width must be 32 bits.
 pub unsafe trait Derivative: Sealed + Default {
     /// Result is the partial derivative of `Self` with respect to the window x coordinate. Uses local differencing
     /// based on the value of `Self`. Same result as either [`Self::dfdx_fine`] or [`Self::dfdx_coarse`] on `Self`. Selection of which

Diff for: tests/ui/arch/derivative.stderr

@@ -1,10 +1,10 @@
 %1 = OpFunction  %2  None %3
 %4 = OpLabel
-OpLine %5 34 8
+OpLine %5 37 8
 %6 = OpDPdx  %7  %8
-OpLine %5 76 8
+OpLine %5 79 8
 %9 = OpDPdy  %7  %8
-OpLine %5 116 8
+OpLine %5 119 8
 %10 = OpFwidth  %7  %8
 OpNoLine
 OpReturn

Diff for: tests/ui/arch/derivative_control.stderr

@@ -1,16 +1,16 @@
 %1 = OpFunction  %2  None %3
 %4 = OpLabel
-OpLine %5 47 8
+OpLine %5 50 8
 %6 = OpDPdxFine  %7  %8
-OpLine %5 89 8
+OpLine %5 92 8
 %9 = OpDPdyFine  %7  %8
-OpLine %5 128 8
+OpLine %5 131 8
 %10 = OpFwidthFine  %7  %8
-OpLine %5 62 8
+OpLine %5 65 8
 %11 = OpDPdxCoarse  %7  %8
-OpLine %5 104 8
+OpLine %5 107 8
 %12 = OpDPdyCoarse  %7  %8
-OpLine %5 140 8
+OpLine %5 143 8
 %13 = OpFwidthCoarse  %7  %8
 OpNoLine
 OpReturn