swc-project
When adding a default value to a function, compress / minify can't optimize the function.
Describe the bug
When a function parameter has a default value, and that parameter is not used, the parameter (and consequently the whole function) are not optimized away.
Input code
const defaultMessage = "hello"
// write or paste code here
function x(x) { return x; }
function y(x, y, z) { return x; };
function abc(a) { return x(a); }
function abc2(a, x, z = defaultMessage) { return y(a); }
export function example() {
// output should be
// return `2 2 3 3`;
return `${x(2)} ${y("2")} ${abc(3)} ${abc2("3")}`;
}
Config
{
"jsc": {
"parser": {
"syntax": "typescript",
"tsx": false
},
"target": "es2022",
"loose": false,
"minify": {
"compress": {
"arguments": false,
"arrows": true,
"booleans": true,
"booleans_as_integers": false,
"collapse_vars": true,
"comparisons": true,
"computed_props": true,
"conditionals": true,
"dead_code": true,
"directives": true,
"drop_console": false,
"drop_debugger": true,
"evaluate": true,
"expression": false,
"hoist_funs": false,
"hoist_props": true,
"hoist_vars": false,
"if_return": true,
"join_vars": true,
"keep_classnames": false,
"keep_fargs": true,
"keep_fnames": false,
"keep_infinity": false,
"loops": true,
"negate_iife": true,
"properties": true,
"reduce_funcs": false,
"reduce_vars": false,
"side_effects": true,
"switches": true,
"typeofs": true,
"unsafe": false,
"unsafe_arrows": false,
"unsafe_comps": false,
"unsafe_Function": false,
"unsafe_math": false,
"unsafe_symbols": false,
"unsafe_methods": false,
"unsafe_proto": false,
"unsafe_regexp": false,
"unsafe_undefined": false,
"unused": true,
"const_to_let": true,
"pristine_globals": true,
"passes": 7
},
"mangle": false,
},
"transform": {
"constModules": {"globals": {"debug": {"IS_DEV_MODE": "false"}}}
}
},
"module": {
"type": "es6"
},
"minify": false,
"isModule": true
}
Playground link (or link to the minimal reproduction)
https://play.swc.rs/?version=1.7.24&code=H4sIAAAAAAAAA11PSwrCMBTc5xRDcBGhIKTL4hG8g7F9tUJsSj6YWnp3n1q%2Fu3nzY17t%2BhDRUGuSjTsKwRwJW8iOrHVSiM0GF3%2BKBOcxmMCgdg2hI0%2BiTX0dT65HVnmNCZ5i8nxVmD%2FaqHKBscD1z1GJj8ccamW%2Bdb5%2BStiglSnAVVde9zv3KzguQUF5cD7iXUDZnAdLir0C4KdcikOKCJ1LtsGBnuxSs9fQKFHuK6Zf3GrKSq9nrKZRSS0f6D68fCGtZMk0h%2BYbmjyxQlYBAAA%3D&config=H4sIAAAAAAAAA32VPY%2FbMAyG9%2FyKQHOHIkMLdL4r0OHQoUBXQbEoR1dbMkQqlyDwfy8lOx%2BX0NlsPiIpkdSr02q9Vu%2FYqB%2FrE3%2Fyz2ASQrr8swWPgcyBLYqOA2CT%2FEDqy5kSFuRMh1BN40QUmdQCFS%2FAzdfNZvZQXYwIZ4%2FZ1vvg3fE2ZxP7IQHijY2tHDL3EAg%2F%2B88sxY8CKOVb%2BzbGDkx4QrRB7QNBC0kK3MSuMwOC3pskRCk7NcljlFIUmAmsHlIcRB6sJx8D53ykFozVTbQgIJ%2BgIb8HyY1zsVtAPp5wnootbHPb1j7fecPedNmQkBMOtSW8WyHqLnok7XKQSjjBhRpMcC7uvad3OgHlFB793qMPCz35B8AV6AxiMD1IcesKx%2FO05O2eevrgeGTpKHCeb%2BmUAVouqvbeCZUtlYFEXupmApsbKJVtpO3MeKF86C1ocI5nRQiNH56anZS0XPToBMD9NU6aqgnoyy1c4OVCPME%2F%2BZQkD9i8oje0W6Z47Lexe5KgB9pF%2B2QBt4LiMk6sEodhmedggUcDrLgkYwWPIsAXgKLuql4%2BzAZfD46o2y5uRZkYeM5rE7%2FPtvEizr0J7b0IXAQ6sfa5mPrPust7eYs2dzXiSV2znlQVjfr1649%2Bef2r336%2FvBaFr9HVOI5TgtWcRPU10PVtKWM1vQjf1HXRWfwve1Qe386e5ayr8T%2FpkujBpwYAAA%3D%3D
SWC Info output
I'm only using the playground
Expected behavior
Behavior without the default value in the function parameter
When a parameter is unused, it shouldn't matter if it has a default value or not.
Actual behavior
function is not optimized away
Version
1.7.24 and newer (didn't test older)
Additional context
No response
I think https://github.com/swc-project/swc/pull/9636 may also solve this problem
Commenting again, due to bot-closures https://github.com/swc-project/swc/issues/8177#issuecomment-1825017067