Add deduction guides for type aliases in prelude

Author: stijnh

include/kernel_float/constant.h

@@ -28,6 +28,12 @@ struct constant {
     T value_;
 };
 
+// Deduction guide for `constant<T>`
+#if defined(__cpp_deduction_guides)
+template<typename T>
+constant(T&&) -> constant<decay_t<T>>;
+#endif
+
 template<typename T = double>
 KERNEL_FLOAT_INLINE constexpr constant<T> make_constant(T value) {
     return value;

include/kernel_float/prelude.h

@@ -1,7 +1,9 @@
 #ifndef KERNEL_FLOAT_PRELUDE_H
 #define KERNEL_FLOAT_PRELUDE_H
 
+#include "bf16.h"
 #include "constant.h"
+#include "fp16.h"
 #include "vector.h"
 
 namespace kernel_float {
@@ -94,6 +96,18 @@ static constexpr kconstant<long long int> operator""_c(unsigned long long int v)
     return static_cast<long long int>(v);
 }
 
+// Deduction guides for aliases are only supported from C++20
+#if defined(__cpp_deduction_guides) && __cpp_deduction_guides >= 201907L
+template<typename T>
+kscalar(T&&) -> kscalar<decay_t<T>>;
+
+template<typename... Args>
+kvec(Args&&...) -> kvec<promote_t<Args...>, sizeof...(Args)>;
+
+template<typename T>
+kconstant(T&&) -> kconstant<decay_t<T>>;
+#endif
+
 }  // namespace prelude
 }  // namespace kernel_float