cgen: fix string interpolation for non-standard integer types

vlib/v/gen/cgen.v

@@ -2284,8 +2284,18 @@ fn (mut g Gen) string_inter_literal(node ast.StringInterLiteral) {
 			g.write('%g')
 		} else if sym.kind == .struct_ && !sym.has_method('str') {
 			g.write('%.*s')
+		} else if node.expr_types[i] == table.i16_type {
+		        g.write('%"PRId16"')
+		} else if node.expr_types[i] == table.u16_type {
+		        g.write('%"PRIu16"')
+		} else if node.expr_types[i] == table.u32_type {
+		        g.write('%"PRIu32"')
+		} else if node.expr_types[i] == table.i64_type {
+		        g.write('%"PRId64"')
+		} else if node.expr_types[i] == table.u64_type {
+		        g.write('%"PRIu64"')
 		} else {
-			g.write('%d')
+			g.write('%"PRId32"')
 		}
 	}
 	g.write('", ')

vlib/v/tests/string_interpolation_test.v

@@ -75,3 +75,15 @@ fn test_string_interpolation_string_prefix() {
 	jsjs := '$js$js'
 	assert jsjs == 'jsjs'
 }
+
+fn test_inttypes_string_interpolation() {
+	s := i16(-23456)
+	us := u16(54321)
+	i := -1622999040
+	ui := u32(3421958087)
+	l := i64(-7694555558525237396)
+	ul := u64(17234006112912956370)
+	assert '$s $us' == '-23456 54321'
+	assert '$ui $i' == '3421958087 -1622999040'
+	assert '$l $ul' == '-7694555558525237396 17234006112912956370'
+}