cargo doc fails with cannot find function bitwise_bin_op_simd_helper when using features=["simd"]

[alamb]

This was noticed by @ritchie46

cargo doc fails with cannot find function bitwise_bin_op_simd_helper when using features=["simd"]

To Reproduce
Create a new empty repo

$ cargo new --bin repro

Add

arrow = {version="4.0.0", default-features = false, features=["simd"]}

to Cargo.toml

Then try to build docs:

cd repro
cargo +nightly doc --all-features

The build fails:

    Checking arrow v4.0.0
error[E0425]: cannot find function `bitwise_bin_op_simd_helper` in this scope
   --> /Users/alamb/.cargo/registry/src/github.com-1ecc6299db9ec823/arrow-4.0.0/src/buffer/ops.rs:258:9
    |
125 | / pub fn bitwise_bin_op_helper<F>(
126 | |     left: &Buffer,
127 | |     left_offset_in_bits: usize,
128 | |     right: &Buffer,
...   |
152 | |     buffer.into()
153 | | }
    | |_- similarly named function `bitwise_bin_op_helper` defined here
...
258 |           bitwise_bin_op_simd_helper(
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `bitwise_bin_op_helper`

error[E0425]: cannot find function `bitwise_bin_op_simd_helper` in this scope
   --> /Users/alamb/.cargo/registry/src/github.com-1ecc6299db9ec823/arrow-4.0.0/src/buffer/ops.rs:369:9
    |
125 | / pub fn bitwise_bin_op_helper<F>(
126 | |     left: &Buffer,
127 | |     left_offset_in_bits: usize,
128 | |     right: &Buffer,
...   |
152 | |     buffer.into()
153 | | }
    | |_- similarly named function `bitwise_bin_op_helper` defined here
...
369 |           bitwise_bin_op_simd_helper(
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `bitwise_bin_op_helper`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0425`.
error: could not compile `arrow`

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed

Expected behavior
Documentation builds successfully, without error

[ChristianBeilschmidt]

I guess there was a similar issue for 3.0.0, for this version it worked only with the combination simd and avx512. I thought it was fixed and added to the CI, but it doesn't seem so.

Cf. https://issues.apache.org/jira/browse/ARROW-11387 and apache/arrow#9337.

[alamb]

I just verified that this is still a problem with latest master from arrow-rs

[jhorstmann]

Does this mean that enabling the simd feature when using arrow as a dependency did not work at all? That would explain why I did not see any performance difference in benchmarks when enabling that feature recently.

[ritchie46]

Ok, I did another test and now apparently this Cargo.toml works for $ cargo +nightly doc --all-features:

[package]
name = "foo"
version = "0.1.0"
authors = ["Ritchie Vink <ritchie46@gmail.com>"]
edition = "2018"

[dependencies]
arrow = {version="5.0.0-SNAPSHOT", git = "https://github.com/apache/arrow-rs", branch = "master", default-feature = false, features = ["simd"]}

And the published version on crates.io fails

[package]
name = "foo"
version = "0.1.0"
authors = ["Ritchie Vink <ritchie46@gmail.com>"]
edition = "2018"

[dependencies]
arrow = {version="4.0.0", default-features = false, features=["simd"]}

with:

error[E0425]: cannot find function `bitwise_bin_op_simd_helper` in this scope
   --> /home/ritchie46/.cargo/registry/src/github.com-1ecc6299db9ec823/arrow-4.0.0/src/buffer/ops.rs:258:9
    |
125 | / pub fn bitwise_bin_op_helper<F>(
126 | |     left: &Buffer,
127 | |     left_offset_in_bits: usize,
128 | |     right: &Buffer,
...   |
152 | |     buffer.into()
153 | | }
    | |_- similarly named function `bitwise_bin_op_helper` defined here
...
258 |           bitwise_bin_op_simd_helper(
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `bitwise_bin_op_helper`

error[E0425]: cannot find function `bitwise_bin_op_simd_helper` in this scope
   --> /home/ritchie46/.cargo/registry/src/github.com-1ecc6299db9ec823/arrow-4.0.0/src/buffer/ops.rs:369:9
    |
125 | / pub fn bitwise_bin_op_helper<F>(
126 | |     left: &Buffer,
127 | |     left_offset_in_bits: usize,
128 | |     right: &Buffer,
...   |
152 | |     buffer.into()
153 | | }
    | |_- similarly named function `bitwise_bin_op_helper` defined here
...
369 |           bitwise_bin_op_simd_helper(
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `bitwise_bin_op_helper`

So apparently this bug is already fixed, but do we know what fixed it?

[houqp]

This might have something to do with the crates.io releases. I am able to get a successful build from 4.4.0 tag (32b835e) if I use git as the crate source. However, the 4.4.0 release in crates.io results in the same simd build error for me.