Rustc strips all symbols on MacOS when strip = "debuginfo" is specified, but not when strip = "symbols" is specified

Consider this basic example:

fn main() {
    std::thread::sleep(std::time::Duration::from_secs_f64(1.0));
}

When compiled with cargo build and the following Cargo.toml:

[profile.dev]
debug = false
strip = "symbols"

we see the following profile with samply record:

That is, all symbols are still there. However, when we instead build with

[profile.dev]
debug = false
strip = "debuginfo"

we see the following profile:

I believe this is a bug, as the documentation for strip specifies that symbols is supposed to be a more aggressive stripping than debuginfo, which is supposed to leave backtrace information mostly intact. We see the opposite behavior.

The following lines of code are suspect:

rust/compiler/rustc_codegen_ssa/src/back/link.rs

Lines 1103 to 1118 in bf6f8a4

    
           if sess.target.is_like_osx { 
        
               let stripcmd = "rust-objcopy"; 
        
               match (strip, crate_type) { 
        
                   (Strip::Debuginfo, _) => { 
        
                       strip_symbols_with_external_utility(sess, stripcmd, out_filename, &["-S"]) 
        
                   } 
        
                   // Per the manpage, `-x` is the maximum safe strip level for dynamic libraries. (#93988) 
        
                   (Strip::Symbols, CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro) => { 
        
                       strip_symbols_with_external_utility(sess, stripcmd, out_filename, &["-x"]) 
        
                   } 
        
                   (Strip::Symbols, _) => { 
        
                       strip_symbols_with_external_utility(sess, stripcmd, out_filename, &[]) 
        
                   } 
        
                   (Strip::None, _) => {} 
        
               } 
        
           }

-S on rust-objcopy is documented as such:

  -S                      Alias for --strip-all

It does not seem appropriate to be used in the Debuginfo branch, but omitted in the Symbols branch.

What made it extra annoying to debug this issue is that the cargo docs lie about the default for strip. It says strip = "none" is the default, but this is not true. The default depends on whether or not debug = false is specified.

This is a regression from stable to nightly, tracked down to #131405.

@rustbot

@rustbot label +T-bootstrap

cc @davidtwco @jieyouxu since #131405

The regression is actually a T-compiler concern, because we used the wrong flags for rust-objcopy in cg_ssa.

Auto merge of rust-lang#135034 - Noratrieb:strip-correctly, r=<try>

Auto merge of rust-lang#135034 - Noratrieb:strip-correctly, r=jieyouxu

Re-opening for the backport.

Backport occurred in #135163 so I'm closing.

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Rustc strips all symbols on MacOS when strip = "debuginfo" is specified, but not when strip = "symbols" is specified #135028

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	if sess.target.is_like_osx {
	let stripcmd = "rust-objcopy";
	match (strip, crate_type) {
	(Strip::Debuginfo, _) => {
	strip_symbols_with_external_utility(sess, stripcmd, out_filename, &["-S"])
	}
	// Per the manpage, `-x` is the maximum safe strip level for dynamic libraries. (#93988)
	(Strip::Symbols, CrateType::Dylib \| CrateType::Cdylib \| CrateType::ProcMacro) => {
	strip_symbols_with_external_utility(sess, stripcmd, out_filename, &["-x"])
	}
	(Strip::Symbols, _) => {
	strip_symbols_with_external_utility(sess, stripcmd, out_filename, &[])
	}
	(Strip::None, _) => {}
	}
	}

Rustc strips all symbols on MacOS when strip = "debuginfo" is specified, but not when strip = "symbols" is specified #135028

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orlp commented on Jan 2, 2025

orlp commented on Jan 2, 2025

apiraino commented on Jan 2, 2025

jieyouxu commented on Jan 2, 2025

Noratrieb commented on Jan 3, 2025

wesleywiser commented on Jan 9, 2025

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