a124043fb0
This commit adds a new stable codegen option to rustc, `-Csplit-debuginfo`. The old `-Zrun-dsymutil` flag is deleted and now subsumed by this stable flag. Additionally `-Zsplit-dwarf` is also subsumed by this flag but still requires `-Zunstable-options` to actually activate. The `-Csplit-debuginfo` flag takes one of three values: * `off` - This indicates that split-debuginfo from the final artifact is not desired. This is not supported on Windows and is the default on Unix platforms except macOS. On macOS this means that `dsymutil` is not executed. * `packed` - This means that debuginfo is desired in one location separate from the main executable. This is the default on Windows (`*.pdb`) and macOS (`*.dSYM`). On other Unix platforms this subsumes `-Zsplit-dwarf=single` and produces a `*.dwp` file. * `unpacked` - This means that debuginfo will be roughly equivalent to object files, meaning that it's throughout the build directory rather than in one location (often the fastest for local development). This is not the default on any platform and is not supported on Windows. Each target can indicate its own default preference for how debuginfo is handled. Almost all platforms default to `off` except for Windows and macOS which default to `packed` for historical reasons. Some equivalencies for previous unstable flags with the new flags are: * `-Zrun-dsymutil=yes` -> `-Csplit-debuginfo=packed` * `-Zrun-dsymutil=no` -> `-Csplit-debuginfo=unpacked` * `-Zsplit-dwarf=single` -> `-Csplit-debuginfo=packed` * `-Zsplit-dwarf=split` -> `-Csplit-debuginfo=unpacked` Note that `-Csplit-debuginfo` still requires `-Zunstable-options` for non-macOS platforms since split-dwarf support was *just* implemented in rustc. There's some more rationale listed on #79361, but the main gist of the motivation for this commit is that `dsymutil` can take quite a long time to execute in debug builds and provides little benefit. This means that incremental compile times appear that much worse on macOS because the compiler is constantly running `dsymutil` over every single binary it produces during `cargo build` (even build scripts!). Ideally rustc would switch to not running `dsymutil` by default, but that's a problem left to get tackled another day. Closes #79361 |
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| Cargo.toml | ||
| README.md | ||
librustc_target contains some very low-level details that are
specific to different compilation targets and so forth.
For more information about how rustc works, see the rustc dev guide.