builtin: string interpolation: binary format support (#11421)

vlib/builtin/string_int_test.v

@@ -219,3 +219,38 @@ fn test_signed_cast() {
 		assert '${u.f:G}' == '-INF'
 	}
 }
+
+fn test_binary() {
+	i := i8(127)
+	u := u8(127)
+	assert '${i:08b}' == '01111111'
+	assert '${u:08b}' == '01111111'
+	assert '${i16(i):08b}' == '01111111'
+	assert '${u16(u):08b}' == '01111111'
+	assert '${int(i):08b}' == '01111111'
+	assert '${u32(u):08b}' == '01111111'
+	assert '${i64(i):08b}' == '01111111'
+	assert '${u64(u):08b}' == '01111111'
+
+	n := i8(-1)
+	assert '${u8(-1):08b}' == '11111111'
+	assert '${u16(n):08b}' == '1111111111111111'
+	assert '${u32(n):08b}' == '11111111111111111111111111111111'
+	assert '${u64(n):08b}' == '1111111111111111111111111111111111111111111111111111111111111111'
+}
+
+fn test_binary32() {
+	i := int(0x7fff_ffff)
+	u := u32(0x7fff_ffff)
+	assert '${i:032b}' == '01111111111111111111111111111111'
+	assert '${u:032b}' == '01111111111111111111111111111111'
+	assert '${i64(i):032b}' == '01111111111111111111111111111111'
+	assert '${u64(u):032b}' == '01111111111111111111111111111111'
+}
+
+fn test_binary64() {
+	i := i64(0x7fff_ffff_ffff_ffff)
+	u := u64(0x7fff_ffff_ffff_ffff)
+	assert '${i:064b}' == '0111111111111111111111111111111111111111111111111111111111111111'
+	assert '${u:064b}' == '0111111111111111111111111111111111111111111111111111111111111111'
+}