Providing the compiler crates as rlib?

[swiftcoder]

I'd like to embed rustc_driver in a static library (for complicated embedded deployment reasons that aren't entirely relevant). Dependencies of a static library seem to have to be in rlib format so the compile can read metadata.

Unfortunately, most of the compiler crates are only building dylibs, causing cargo to refuse to build a staticlib:

error: crate `rustc_driver` required to be available in rlib format, but was not found in this form
error: crate `arena` required to be available in rlib format, but was not found in this form
error: crate `rustc_data_structures` required to be available in rlib format, but was not found in this form
error: crate `graphviz` required to be available in rlib format, but was not found in this form
error: crate `rustc_cratesio_shim` required to be available in rlib format, but was not found in this for
error: crate `rustc` required to be available in rlib format, but was not found in this form
error: crate `fmt_macros` required to be available in rlib format, but was not found in this form
error: crate `rustc_target` required to be available in rlib format, but was not found in this form
error: crate `rustc_errors` required to be available in rlib format, but was not found in this form
error: crate `syntax_pos` required to be available in rlib format, but was not found in this form
error: crate `syntax` required to be available in rlib format, but was not found in this form
error: crate `proc_macro` required to be available in rlib format, but was not found in this form
error: crate `rustc_fs_util` required to be available in rlib format, but was not found in this form
error: crate `rustc_allocator` required to be available in rlib format, but was not found in this form
error: crate `rustc_borrowck` required to be available in rlib format, but was not found in this form
error: crate `rustc_mir` required to be available in rlib format, but was not found in this form
error: crate `rustc_passes` required to be available in rlib format, but was not found in this form
error: crate `rustc_lint` required to be available in rlib format, but was not found in this form
error: crate `rustc_plugin` required to be available in rlib format, but was not found in this form
error: crate `rustc_metadata` required to be available in rlib format, but was not found in this form
error: crate `syntax_ext` required to be available in rlib format, but was not found in this form
error: crate `rustc_privacy` required to be available in rlib format, but was not found in this form
error: crate `rustc_typeck` required to be available in rlib format, but was not found in this form
error: crate `rustc_platform_intrinsics` required to be available in rlib format, but was not found in this form
error: crate `rustc_incremental` required to be available in rlib format, but was not found in this form
error: crate `rustc_resolve` required to be available in rlib format, but was not found in this form
error: crate `rustc_save_analysis` required to be available in rlib format, but was not found in this form
error: crate `rustc_codegen_utils` required to be available in rlib format, but was not found in this form
error: crate `rustc_traits` required to be available in rlib format, but was not found in this form

error: aborting due to 29 previous errors

Is there a technical reason why these are all only built as dylib, or is this just because no one has thus far needed to embed them in a staticlib? Would it be a reasonable ask to configure these projects to build both flavours?

[Centril]

@Zoxc is this fixed now given the move away from dylibs?

[mati865]

There are still few dylibs left.

[bjorn3]

The only dylib only crates left are rustc_driver and rustc_codegen_cranelift.

https://github.com/rust-lang/rust/search?l=TOML&q=crate-type+%3D+%5B%22dylib%22%5D

rustc_codegen_cranelift must always be built as dylib, as it can't be loaded at runtime otherwise. Making rustc_driver available as rlib will cause many tools to accidentally build against it as static lib, which shouldn't normally happen as it greatly increases the size of the tool executables and prevents runtime loading of codegen backends.

[jyn514]

I'm going to close this, this is not a use case we plan to support. If you need to embed rustc_driver as a static library for whatever reason, you can fork the project and remove crate-type = "dylib":

rust/compiler/rustc_driver/Cargo.toml

Lines 6 to 7 in 1fc86a6

	[lib]
	crate-type = ["dylib"]

[Zoxc]

My PR will allow for this. You won't be able to load codegen backends without further modifications though.