Compiler Explorer

Source code

void fn3x2(float3x2) {}
void fn2x2(float2x2) {}
void fn2x2IO(inout float2x2) {}
void fnI2x2IO(inout int2x2) {}

void matOrVec(float4 F) {}
void matOrVec(float2x2 F) {}

void matOrVec2(float3 F) {}
void matOrVec2(float2x3 F) {}

export void cases(float2x3 f23, float4x4 f44, float3x3 f33, float3x2 f32) {
  int2x2 i22 = f23; // Allowed!
#ifdef ERROR
  int3x2 i32 = f23; // Error!
  fn3x2(f23); // Error!
#endif
  fn2x2(f23); // Allowed!
#ifdef ERROR
  // DXC disallows these, and I'm really unsure why...
  fn2x2IO(f23); // Maybe allowed?
  fnI2x2IO(f23); // Maybe allowed?
#endif

matOrVec(f23); // calls matOrVec(float2x2);
  matOrVec(f44); // calls matOrVec(float2x2);
#ifdef ERROR
  matOrVec(2.0); // Ambiguous!

matOrVec2(f23); // No viable conversion!
#endif

matOrVec2(f44); // calls matOrVec(float2x3);
  matOrVec2(f33); // calls matOrVec(float2x3);
#ifdef ERROR
  // I think the current language in the spec is wrong about this one!
  matOrVec2(f32); // No known conversion from matrix to vector!
#endif
}