compiler: implement comparing structs directly

testdata/binop.go

@@ -0,0 +1,43 @@
+package main
+
+func main() {
+	// string equality
+	println(a == "a")
+	println(a == "b")
+	println(a != "a")
+	println(a != "b")
+
+	// struct equality
+	println(s1 == Struct1{3, true})
+	println(s1 == Struct1{4, true})
+	println(s1 == Struct1{3, false})
+	println(s1 == Struct1{4, false})
+	println(s1 != Struct1{3, true})
+	println(s1 != Struct1{4, true})
+	println(s1 != Struct1{3, false})
+	println(s1 != Struct1{4, false})
+
+	// blank fields in structs
+	println(s2 == Struct2{"foo", 0.0, 5})
+	println(s2 == Struct2{"foo", 0.0, 7})
+	println(s2 == Struct2{"foo", 1.0, 5})
+	println(s2 == Struct2{"foo", 1.0, 7})
+}
+
+var x = true
+var y = false
+
+var a = "a"
+var s1 = Struct1{3, true}
+var s2 = Struct2{"foo", 0.0, 5}
+
+type Struct1 struct {
+	i int
+	b bool
+}
+
+type Struct2 struct {
+	s string
+	_ float64
+	i int
+}