100% binary size increase (7.7M to 15M) when clap 3 added as a dep

[osa1]

Note: this is with debug=true in release profile.

I have an application with 145 dependencies (without clap) that builds to 7.7M release binary (LTO enabled).

If I add clap

clap = { version = "3.0.11", features = ["cargo"]

and this CLI parser:

use clap::{crate_authors, crate_name, crate_version, App, Arg};

#[derive(Debug)]
pub struct Args {
    pub file: Option<String>,
    pub fork: bool,
}

impl Args {
    pub fn parse() -> Self {
        let mut version = crate_version!().to_owned();
        let commit_hash = env!("GIT_HASH");
        if !commit_hash.is_empty() {
            version = format!("{} ({})", version, commit_hash);
        }

        let matches = App::new(crate_name!())
            .version(version.as_str())
            .author(crate_authors!())
            .arg(Arg::new("file").value_name("FILE").takes_value(true))
            .arg(Arg::new("fork").takes_value(false).long("fork"))
            .get_matches();

        let file = matches.value_of("file").map(|s| s.to_owned());
        let fork = matches.is_present("fork");

        Args { file, fork }
    }
}

The binary size increases from 7.7M to 15M. I tried clean build and got the same result.

It's a bit strange that clap adds 7.3M to a 6779 sloc (no comments or whitespace) app with 145 dependencies (without clap), so wanted to report it here.

cargo bloat --release output (non-clap and non-std functions snipped):

File  .text     Size        Crate Name
0.5%   7.7%  72.0KiB 
0.4%   7.0%  65.1KiB 
0.3%   4.4%  41.3KiB         clap clap::parse::parser::Parser::get_matches_with
0.2%   2.9%  27.3KiB 
0.2%   2.5%  23.3KiB         clap clap::parse::validator::Validator::validate
0.1%   2.2%  20.3KiB 
0.1%   2.0%  19.0KiB
0.1%   1.8%  16.5KiB         clap clap::parse::validator::Validator::validate_arg_values
0.1%   1.4%  13.4KiB         clap clap::output::help::Help::write_templated_help
0.1%   1.3%  12.3KiB         clap clap::output::help::Help::write_subcommands
0.1%   1.3%  12.3KiB
0.1%   1.3%  12.1KiB          std std::sys::unix::process::process_inner::<impl std::sys::unix::process::process_common::Command>::spawn
0.1%   1.2%  11.0KiB       
0.1%   1.2%  10.8KiB         clap clap::output::usage::Usage::get_required_usage_from
0.1%   1.1%   9.8KiB         clap clap::output::help::Help::write_args
0.1%   1.1%   9.8KiB         clap clap::build::app::App::_build
0.1%   1.0%   9.8KiB      
0.1%   1.0%   9.8KiB          std addr2line::ResUnit<R>::parse_lines
0.1%   0.9%   8.6KiB     
0.1%   0.9%   8.4KiB          std miniz_oxide::inflate::core::decompress
3.5%  54.8% 510.9KiB              And 1055 smaller methods. Use -n N to show more.
6.4% 100.0% 932.3KiB              .text section size, the file size is 14.2MiB

I just realized I have debug=true in release profile. Without debug=true it adds 30%, from 2.3M to 3M.

[epage]

Interesting. When we measured this (default release settings), clap only added 600KB. I'm assuming that debug=false is the default since that seems to jive with the increase you saw.

We have #1365 which will be a focus moving forward with efforts like

• Offering disabling of help generation with the option of code-genned help
• Moving logic out of App and into trait objects that get passed in so the compiler can more easily optimize the code away