cmd/gc: reject complex calls with mismatched argument types.

The specification says "the two arguments must be of the same
floating-point type."

R=rsc, gri
CC=golang-dev
https://golang.org/cl/7671045

src/cmd/gc/typecheck.c

@@ -1182,9 +1182,9 @@ reswitch:
 		defaultlit2(&l, &r, 0);
 		n->left = l;
 		n->right = r;
-		if(l->type->etype != r->type->etype) {
+		if(!eqtype(l->type, r->type)) {
 		badcmplx:
-			yyerror("invalid operation: %N (complex of types %T, %T)", n, l->type, r->type);
+			yyerror("invalid operation: %N (mismatched types %T and %T)", n, l->type, r->type);
 			goto error;
 		}
 		switch(l->type->etype) {

test/cmplx.go

@@ -9,12 +9,23 @@
 
 package main
 
+type (
+	Float32    float32
+	Float64    float64
+	Complex64  complex64
+	Complex128 complex128
+)
+
 var (
 	f32 float32
 	f64 float64
+	F32 Float32
+	F64 Float64
 
 	c64  complex64
 	c128 complex128
+	C64  Complex64
+	C128 Complex128
 )
 
 func main() {
@@ -25,4 +36,19 @@ func main() {
 	_ = complex128(0)     // ok
 	_ = complex(f32, f64) // ERROR "complex"
 	_ = complex(f64, f32) // ERROR "complex"
+	_ = complex(f32, F32) // ERROR "complex"
+	_ = complex(F32, f32) // ERROR "complex"
+	_ = complex(f64, F64) // ERROR "complex"
+	_ = complex(F64, f64) // ERROR "complex"
+
+	c128 = complex(f32, f32) // ERROR "cannot use"
+	c64 = complex(f64, f64)  // ERROR "cannot use"
+
+	c64 = complex(1.0, 2.0) // ok, constant is untyped
+	c128 = complex(1.0, 2.0)
+	C64 = complex(1.0, 2.0)
+	C128 = complex(1.0, 2.0)
+
+	C64 = complex(f32, f32)  // ERROR "cannot use"
+	C128 = complex(f64, f64) // ERROR "cannot use"
 }