syn-file-expand

This library allows you to load full source code of multi-file crates into a single syn::File.

Features:

• Based on syn crate.
• Handling #[path] attributes
• Handling #[cfg] where it affects modules to filesystem mapping
• There is both a lower-level IO-less function and a simpler one that just loads crate from a std::fs::Path.

Limitation:

• cfg_if like this is not handled.

Start exploring the library from the read_crate function.

Bonus: CLI tool

syn-file-expand-cli tool expands Rust sources, like cargo expand, but without macro expansion, only for modules. rustc is not involved. Filtering through rustfmt is adviced for debugging use case.

```text $ syn-file-expand-cli -fTp src/lib.rs

![doc = include_str!("../README.md")]

![forbid(unsafe_code)]

... mod attrs { use procmacro2; ... } mod expandimpl { use std::path::PathBuf; ... }

$ syn-file-expand-cli --help Usage: syn-file-expand-cli [OPTIONS]

Use syn-file-expand-cli -fTp src/lib.rs as a starting point.

Reads rust source file, including referred modules and expands them into a single source with all modules inline Apart from respective dedicated command line arguments, conditional paths like #[cfg_attr(feature="qqq"),path=...) are resolved using environment variables like SYNFILEEXPANDFEATUREQQQ=1 Other influential envvars: SYNFILEEXPANDDEBUGVARS=1 SYNFILEEXPANDDEFAULTTRUE=1

Positional arguments: input_file Input Rust source file to start crawling from

Optional arguments: -h, --help -l, --loopify Convert all blocks and expressions to loop{}s. Note that inner items within blocks get lost in the process. -D, --undoc Strip all documentation attributes. Note that inner items within blocks are not processed and may retain their attributes. -T, --cfg-true-by-default Assume all #[cfg]s and #[cfg_attr]s are true. May lead to errors unless -f is also used. -f, --full-crate-tree Allow duplicate modules, also preserve/transform some cfg attributes. -c, --cfg CFG Set this cfg check result to true. Note that all or any are not handled. You need to set all needed expression results one by one. Strings required for --cfg are not the same as for environment variables- -based version of this feature. -u, --unset-cfg UNSET-CFG In --cfg-true-by-default mode, explicitly unset given cfg expression outcome. -d, --debug-cfg Print each encountered cfg check to stderr, in form suitable for --cfg parameter Note that the format is different from the one used by SYN_FILE_EXPAND_DEBUGVARS=1 environment variable. -o, --output OUTPUT Use given file for output instead of stdout -p, --pretty Use prettyplease to format the output

```

There is a Github release with the tool pre-built for various platforms.
You can also install the tool using cargo install syn-file-expand-cli.