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-Zembed-source: also embed external source#155995

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Mrmaxmeier wants to merge 1 commit intorust-lang:mainfrom
Mrmaxmeier:debuginfo-embed-external-source
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-Zembed-source: also embed external source#155995
Mrmaxmeier wants to merge 1 commit intorust-lang:mainfrom
Mrmaxmeier:debuginfo-embed-external-source

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@Mrmaxmeier Mrmaxmeier commented Apr 30, 2026

Hi,

I've been using -Zembed-source for a while and noticed that some sources are not embedded when compiling in release mode. See the minimal reproducer below for missing embedded source code.

The current implementation only emits source from the src field in SourceFile, but for multi-codegen-unit scenarios the source might only be available via the external_src field.

I've updated the LLVM and Cranelift backends to fall back to external_src if src is not available.

Minimal reproducer:

$ cat Cargo.toml
[package]
name = "repro"
version = "0.0.1"
edition = "2021"
[profile.release]
strip = "none"
debug = true
$ cat src/lib.rs
// marker comment
pub fn foo() -> u64 { 42 }
$ cat src/main.rs
fn main() {
    println!("{}", repro::foo());
}
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo build -r
   Compiling repro v0.0.1 (/tmp/repro)
    Finished `release` profile [optimized + debuginfo] target(s) in 0.08s
$ # Note: Source for lib.rs is missing here:
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo +stage1 build -r
    Finished `release` profile [optimized + debuginfo] target(s) in 0.04s
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
         source: "// marker comment\npub fn foo() -> u64 { 42 }\n"

Thanks!

@Mrmaxmeier
debuginfo: embed external source
84daca4 
This allows embedding source code even when it's only available via
previously emitted metadata files.

Without this, embedded source availability is inconsistent, especially
in release builds.
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rustbot commented Apr 30, 2026

The Cranelift subtree was changed

cc @bjorn3

@rustbot rustbot added A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 30, 2026
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rustbot commented Apr 30, 2026

r? @oli-obk

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oli-obk
oli-obk approved these changes May 1, 2026
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@bors r+ rollup

cc @davidtwco

View changes since this review

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rust-bors Bot commented May 1, 2026

📌 Commit 84daca4 has been approved by oli-obk

It is now in the queue for this repository.

@rust-bors rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 1, 2026
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request May 1, 2026
@JonathanBrouwer
Rollup merge of rust-lang#155995 - Mrmaxmeier:debuginfo-embed-externa…
afd1840 
…l-source, r=oli-obk

-Zembed-source: also embed external source

Hi,

I've been using `-Zembed-source` for a while and noticed that some sources are not embedded when compiling in release mode. See the minimal reproducer below for missing embedded source code.

The current implementation only emits source from the `src` field in `SourceFile`, but for multi-codegen-unit scenarios the source might only be available via the `external_src` field.

I've updated the LLVM and Cranelift backends to fall back to `external_src` if `src` is not available.

Minimal reproducer:
```console
$ cat Cargo.toml
[package]
name = "repro"
version = "0.0.1"
edition = "2021"
[profile.release]
strip = "none"
debug = true
$ cat src/lib.rs
// marker comment
pub fn foo() -> u64 { 42 }
$ cat src/main.rs
fn main() {
    println!("{}", repro::foo());
}
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo build -r
   Compiling repro v0.0.1 (/tmp/repro)
    Finished `release` profile [optimized + debuginfo] target(s) in 0.08s
$ # Note: Source for lib.rs is missing here:
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo +stage1 build -r
    Finished `release` profile [optimized + debuginfo] target(s) in 0.04s
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
         source: "// marker comment\npub fn foo() -> u64 { 42 }\n"
```

Thanks!
@JonathanBrouwer JonathanBrouwer mentioned this pull request May 1, 2026
Closed
jhpratt added a commit to jhpratt/rust that referenced this pull request May 1, 2026
@jhpratt
Rollup merge of rust-lang#155995 - Mrmaxmeier:debuginfo-embed-externa…
e1b7a65 
…l-source, r=oli-obk

-Zembed-source: also embed external source

Hi,

I've been using `-Zembed-source` for a while and noticed that some sources are not embedded when compiling in release mode. See the minimal reproducer below for missing embedded source code.

The current implementation only emits source from the `src` field in `SourceFile`, but for multi-codegen-unit scenarios the source might only be available via the `external_src` field.

I've updated the LLVM and Cranelift backends to fall back to `external_src` if `src` is not available.

Minimal reproducer:
```console
$ cat Cargo.toml
[package]
name = "repro"
version = "0.0.1"
edition = "2021"
[profile.release]
strip = "none"
debug = true
$ cat src/lib.rs
// marker comment
pub fn foo() -> u64 { 42 }
$ cat src/main.rs
fn main() {
    println!("{}", repro::foo());
}
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo build -r
   Compiling repro v0.0.1 (/tmp/repro)
    Finished `release` profile [optimized + debuginfo] target(s) in 0.08s
$ # Note: Source for lib.rs is missing here:
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo +stage1 build -r
    Finished `release` profile [optimized + debuginfo] target(s) in 0.04s
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
         source: "// marker comment\npub fn foo() -> u64 { 42 }\n"
```

Thanks!
@jhpratt jhpratt mentioned this pull request May 1, 2026
Closed
rust-bors Bot pushed a commit that referenced this pull request May 1, 2026
@bors
Auto merge of #156036 - jhpratt:rollup-FAjbWYG, r=jhpratt
80cd51e 
Rollup of 6 pull requests

Successful merges:

 - #149637 (Do not run jump-threading for GPUs)
 - #155948 (Fix order-dependent visibility diagnostics)
 - #155600 (Adds a couple UI tests for polonius)
 - #155995 (-Zembed-source: also embed external source)
 - #156019 (Feed cleanups)
 - #156031 (Return a single diagnostic from `lex_token_trees`.)
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request May 1, 2026
@JonathanBrouwer
Rollup merge of rust-lang#155995 - Mrmaxmeier:debuginfo-embed-externa…
6d8e125 
…l-source, r=oli-obk

-Zembed-source: also embed external source

Hi,

I've been using `-Zembed-source` for a while and noticed that some sources are not embedded when compiling in release mode. See the minimal reproducer below for missing embedded source code.

The current implementation only emits source from the `src` field in `SourceFile`, but for multi-codegen-unit scenarios the source might only be available via the `external_src` field.

I've updated the LLVM and Cranelift backends to fall back to `external_src` if `src` is not available.

Minimal reproducer:
```console
$ cat Cargo.toml
[package]
name = "repro"
version = "0.0.1"
edition = "2021"
[profile.release]
strip = "none"
debug = true
$ cat src/lib.rs
// marker comment
pub fn foo() -> u64 { 42 }
$ cat src/main.rs
fn main() {
    println!("{}", repro::foo());
}
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo build -r
   Compiling repro v0.0.1 (/tmp/repro)
    Finished `release` profile [optimized + debuginfo] target(s) in 0.08s
$ # Note: Source for lib.rs is missing here:
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
$ RUSTFLAGS="-g -Zembed-source=yes -Zdwarf-version=5" cargo +stage1 build -r
    Finished `release` profile [optimized + debuginfo] target(s) in 0.04s
$ llvm-dwarfdump --debug-line target/release/repro | grep "marker comment"
         source: "// marker comment\npub fn foo() -> u64 { 42 }\n"
```

Thanks!
@JonathanBrouwer JonathanBrouwer mentioned this pull request May 1, 2026
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