Build error using --no-default-features

[riklus]

My Issue

System info: MacBook Pro Retina Late-2013 (Intel)

• cargo 1.67.1 (8ecd4f20a 2023-01-10)
• rustc 1.67.1 (d5a82bbd2 2023-02-07)
• Target: x86_64-apple-darwin

To reproduce this bug:

1. Clone this repo with the --recurse-submodules option and cd rs-nfc1-sys
2. Run cargo check --no-default-features

   Compiling memchr v2.5.0
   Compiling glob v0.3.1
   Compiling libc v0.2.139
   Compiling proc-macro2 v1.0.51
   Compiling cfg-if v1.0.0
   Compiling quote v1.0.23
   Compiling unicode-ident v1.0.6
   Compiling clang-sys v1.4.0
   Compiling log v0.4.17
   Compiling minimal-lexical v0.2.1
   Compiling syn v1.0.107
   Compiling nom v7.1.3
   Compiling libloading v0.7.4
   Compiling regex-syntax v0.6.28
   Compiling either v1.8.1
   Compiling bindgen v0.63.0
   Compiling which v4.4.0
   Compiling regex v1.7.1
   Compiling cexpr v0.6.0
   Compiling shlex v1.1.0
   Compiling lazy_static v1.4.0
   Compiling peeking_take_while v0.1.2
   Compiling rustc-hash v1.1.0
   Compiling lazycell v1.3.0
   Compiling bitflags v1.3.2
   Compiling pkg-config v0.3.26
   Compiling cc v1.0.79
   Compiling nfc1-sys v0.3.1 (/Users/username/github/rs-nfc1-sys)
error[E0463]: can't find crate for `cmake`
 --> build.rs:2:1
  |
2 | extern crate cmake;
  | ^^^^^^^^^^^^^^^^^^^ can't find crate

warning: unused macro definition: `on_by_feature`
  --> build.rs:15:14
   |
15 | macro_rules! on_by_feature {
   |              ^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_macros)]` on by default

error[E0425]: cannot find function `make_source` in this scope
   --> build.rs:225:3
    |
225 |         make_source(&nfc_dir, &out_dir)
    |         ^^^^^^^^^^^ not found in this scope

Some errors have detailed explanations: E0425, E0463.
For more information about an error, try `rustc --explain E0425`.
warning: `nfc1-sys` (build script) generated 1 warning
error: could not compile `nfc1-sys` due to 2 previous errors; 1 warning emitted

Seems like disabling all features also disables cmake that it's needed to link the libraries.

I encountered this problem here as well: alexrsagen/rs-nfc1#8 (comment)

The fixes I tried

By reenabling cmake with this cargo check --no-default-features --features=cmake:

   Compiling nfc1-sys v0.3.1 (/Users/username/github/rs-nfc1-sys)
warning: unused macro definition: `on_by_feature`
  --> build.rs:15:14
   |
15 | macro_rules! on_by_feature {
   |              ^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_macros)]` on by default

error[E0425]: cannot find function `make_source` in this scope
   --> build.rs:225:3
    |
225 |         make_source(&nfc_dir, &out_dir)
    |         ^^^^^^^^^^^ not found in this scope

For more information about this error, try `rustc --explain E0425`.
warning: `nfc1-sys` (build script) generated 1 warning
error: could not compile `nfc1-sys` due to previous error; 1 warning emitted

The function make_source is not found in the scope that's because the function is declared like this:

rs-nfc1-sys/build.rs

Lines 118 to 119 in 6247d15

	#[cfg(feature = "vendored")]
	fn make_source(nfc_dir: &PathBuf, out_dir: &PathBuf) -> Package {

And by disabling all features we also disable the vendored feature and the function make_source goes out of scope. A fix for this could be removing the #[cfg(feature = "vendored")] macro since the control on the feature is also done in the main

rs-nfc1-sys/build.rs

Lines 224 to 229 in 6247d15

	let libnfc_pkg = if cfg!(feature = "vendored") {
	make_source(&nfc_dir, &out_dir)
	} else {
	find_libnfc_pkg(cfg!(target_feature = "crt-static"))
	.expect("libnfc not found.")
	};

Done that it compiles and all tests pass. ✅

   Compiling nfc1-sys v0.3.1 (/Users/username/github/rs-nfc1-sys)
    Finished dev [unoptimized + debuginfo] target(s) in 17.89s

Suggestions

Disabling all features shouldn't make the module not buildable.

Solutions could be:

• Declaring cmake as not optional?
• Remove the #[cfg(feature = "vendored")] macro on make_source?

Let me know what you think an I could pull a request to fix these.

[alexrsagen]

Thanks for reporting this (great description and good detail!)

I've implemented some of your suggestions in #7 and tested using cargo check --no-default-features before and after.

I believe this should be solved in 0.3.2, can you confirm @riklus ?

[riklus]

Tried compiling and it returns this error:

error[E0433]: failed to resolve: use of undeclared crate or module `cmake`
   --> build.rs:112:18
    |
112 |     config: &mut cmake::Config,
    |                  ^^^^^ use of undeclared crate or module `cmake`

For more information about this error, try `rustc --explain E0433`.

I think it's because cmake is not imported when all features are disabled and the function set_unix_like_libusb_config uses it.

[alexrsagen]

Yep, missed that one. Should be fixed in ca4642c / v0.3.3.

If it works fine now, I will publish v0.3.3 to crates.io

[riklus]

Unfortunatley no. It displays the same error.
On a macos/linux system this #[cfg(not(all(target_os = "windows", feature = "vendored")))] evaluates to true.

[alexrsagen]

Yeah my bad, too hasty fix.

This should work: #[cfg(all(not(target_os = "windows"), feature = "vendored"))]

Pushed v0.3.4 now, can you test if this works @riklus ?

[riklus]

Yay it works! Good job!

[alexrsagen]

Thanks for your help diagnosing/fixing the issue.
v0.3.4 now published to crates.io 😄