Build fails with customized cargo target dir

[ksqsf]

I changed the default target dir in ~/.cargo/config

[build]
target-dir = "~/.cache/cargo"

remacs seems to use the default path regardless of this setting.

  CCLD     etags
clang: error: no such file or directory: '../rust_src/target/release/libremacs_lib.a'

[ksqsf]

To fix it:

configure.ac

LDFLAGS_REMACS="-L`(cd rust_src && cargo metadata --format-version=1 | jq -r .target_directory)`/\${CARGO_BUILD_DIR}"

lib-src/Makefile.in

RUST_ARCHIVE = `(cd ../rust_src && cargo metadata --format-version=1 | jq -r .target_directory)`/$(CARGO_BUILD_DIR)/$(REMACSLIB_NAME)

This depends on jq.

[shaleh]

Can you link to some upstream docs? This seems like a lot to ask every project to bend to the user's settings. Shouldn't cargo handle this for us?

[ksqsf]

My comment above uses cargo metadata which is handled by cargo itself, so this should be the expected solution. I don't know how to reliably and portably extract the target_directory field from the returned json though.

edit: and cargo does handle this. The problem is that remacs hard-coded the target dir path.

[shaleh]

Right, what I am asking is why does our project need to change to handle this? Shouldn't cargo know where to write files based on its own config? Are we doing something out of the ordinary?

[ksqsf]

• https://github.com/remacs/remacs/blob/master/configure.ac#L5120
• https://github.com/remacs/remacs/blob/master/lib-src/Makefile.in#L196

The target dir is hardcoded to be toplevel/rust_src/target. This leads to the very compilation error I encountered.

So it's like, cargo places the archive at ~/.cache/cargo/release/libwhatever.a as intended, but the linker looks for it under $toplevel/rust_src/target/release/.

[shaleh]

Got it. Thank you.