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Warn if a function is marked as both #[inline] and #[no_mangle] #72944

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fschutt opened this issue Jun 3, 2020 · 2 comments · Fixed by #73034
Closed

Warn if a function is marked as both #[inline] and #[no_mangle] #72944

fschutt opened this issue Jun 3, 2020 · 2 comments · Fixed by #73034
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A-FFI Area: Foreign function interface (FFI) A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` C-feature-request Category: A feature request, i.e: not implemented / a PR. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@fschutt
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fschutt commented Jun 3, 2020 •
edited by rustbot
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Code:

// src/lib.rs
#[inline] #[no_mangle] pub extern "C" fn foo() { }
# Cargo.toml
[package]
name = "foo"
version = "0.0.1"
edition = "2018"

[lib]
name = "foo"
crate-type = ["cdylib"]
cargo build --release

If the function is marked as #[inline], it doesn't get compiled into the dll file:

strings target/release/libfoo.so | grep foo

The reason a function may be marked as both #[inline] and #[no_mangle] is so that it gets inlined when compiling the crate as a rust library, but not inlined when compiling the crate as a cdylib.

There should be a warning to use something like #[cfg_attr(not(crate_type="cdylib"), inline] instead.

This issue has been assigned to @doctorn via this comment.
fschutt added a commit to fschutt/azul that referenced this issue Jun 3, 2020
@fschutt
Remove #[inline] from azul-dll functions (see rust-lang/rust#72944)
39014f3
@Elinvynia Elinvynia added A-FFI Area: Foreign function interface (FFI) A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` C-feature-request Category: A feature request, i.e: not implemented / a PR. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 3, 2020
@doctorn
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doctorn commented Jun 5, 2020

Related to #72463 - I think is that we should include #[inline]'d functions in cdylibs and staticlibs, but as a short term solution, a warning is a nice idea

@doctorn
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doctorn commented Jun 5, 2020

@rustbot claim

@rustbot rustbot self-assigned this Jun 5, 2020
@doctorn doctorn mentioned this issue Jun 5, 2020
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Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this issue Jun 11, 2020
@Dylan-DPC
Rollup merge of rust-lang#73034 - doctorn:nomangle-inline-linkage, r=…
f31414d 
…matthewjasper

Export `#[inline]` fns with extern indicators

In ancient history (rust-lang#36280) we stopped `#[inline]` fns being codegened if they weren't used. However,

- rust-lang#72944
- rust-lang#72463

observe that when writing something like

```rust
#![crate_type = "cdylib"]

#[no_mangle]
#[inline]
pub extern "C" fn foo() {
    // ...
}
```

we really _do_ want `foo` to be codegened. This change makes this the case.

Resolves rust-lang#72944, resolves rust-lang#72463 (and maybe some more)
Manishearth added a commit to Manishearth/rust that referenced this issue Jun 16, 2020
@Manishearth
Rollup merge of rust-lang#73034 - doctorn:nomangle-inline-linkage, r=…
3bbc4fd 
…matthewjasper

Export `#[inline]` fns with extern indicators

In ancient history (rust-lang#36280) we stopped `#[inline]` fns being codegened if they weren't used. However,

- rust-lang#72944
- rust-lang#72463

observe that when writing something like

```rust
#![crate_type = "cdylib"]

#[no_mangle]
#[inline]
pub extern "C" fn foo() {
    // ...
}
```

we really _do_ want `foo` to be codegened. This change makes this the case.

Resolves rust-lang#72944, resolves rust-lang#72463 (and maybe some more)
Manishearth added a commit to Manishearth/rust that referenced this issue Jun 18, 2020
@Manishearth
Rollup merge of rust-lang#73034 - doctorn:nomangle-inline-linkage, r=…
89825e2 
…matthewjasper

Export `#[inline]` fns with extern indicators

In ancient history (rust-lang#36280) we stopped `#[inline]` fns being codegened if they weren't used. However,

- rust-lang#72944
- rust-lang#72463

observe that when writing something like

```rust
#![crate_type = "cdylib"]

#[no_mangle]
#[inline]
pub extern "C" fn foo() {
    // ...
}
```

we really _do_ want `foo` to be codegened. This change makes this the case.

Resolves rust-lang#72944, resolves rust-lang#72463 (and maybe some more)
@bors bors closed this as completed in 0e332e9 Jun 19, 2020
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A-FFI Area: Foreign function interface (FFI) A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` C-feature-request Category: A feature request, i.e: not implemented / a PR. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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Export #[inline] fns with extern indicators
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@doctorn @fschutt @rustbot @Elinvynia