Auto merge of #52445 - alexcrichton:wasm-import-module, r=eddyb

rustc: Stabilize #[wasm_import_module] as #[link(...)]

This commit stabilizes the `#[wasm_import_module]` attribute as
`#[link(wasm_import_module = "...")]`. Tracked by #52090 this new directive in
the `#[link]` attribute is used to configured the module name that the imports
are listed with. The WebAssembly specification indicates two utf-8 names are
associated with all imported items, one for the module the item comes from and
one for the item itself. The item itself is configurable in Rust via its
identifier or `#[link_name = "..."]`, but the module name was previously not
configurable and defaulted to `"env"`. This commit ensures that this is also
configurable.

Closes #52090

src/test/run-make/wasm-import-module/bar.rs

@@ -9,12 +9,11 @@
 // except according to those terms.
 
 #![crate_type = "cdylib"]
-#![feature(wasm_import_module)]
 #![deny(warnings)]
 
 extern crate foo;
 
-#[wasm_import_module = "./me"]
+#[link(wasm_import_module = "./me")]
 extern {
     #[link_name = "me_in_dep"]
     fn dep();

src/test/run-make/wasm-import-module/foo.rs

@@ -9,10 +9,9 @@
 // except according to those terms.
 
 #![crate_type = "rlib"]
-#![feature(wasm_import_module)]
 #![deny(warnings)]
 
-#[wasm_import_module = "./dep"]
+#[link(wasm_import_module = "./dep")]
 extern {
     pub fn dep();
 }

src/test/ui/error-codes/E0458.stderr

@@ -2,7 +2,9 @@ error[E0458]: unknown kind: `wonderful_unicorn`
   --> $DIR/E0458.rs:11:1
    |
 LL | #[link(kind = "wonderful_unicorn")] extern {} //~ ERROR E0458
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unknown kind
+   | ^^^^^^^--------------------------^^
+   |        |
+   |        unknown kind
 
 error[E0459]: #[link(...)] specified without `name = "foo"`
   --> $DIR/E0458.rs:11:1

src/test/ui/feature-gate-wasm_import_module.rs

@@ -1,15 +0,0 @@
-// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-#[wasm_import_module = "test"] //~ ERROR: experimental
-extern {
-}
-
-fn main() {}

src/test/ui/feature-gate-wasm_import_module.stderr

@@ -1,11 +0,0 @@
-error[E0658]: experimental attribute (see issue #52090)
-  --> $DIR/feature-gate-wasm_import_module.rs:11:1
-   |
-LL | #[wasm_import_module = "test"] //~ ERROR: experimental
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(wasm_import_module)] to the crate attributes to enable
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/issue-43926.stderr

@@ -1,8 +1,8 @@
 error: `cfg()` must have an argument
-  --> $DIR/issue-43926.rs:11:1
+  --> $DIR/issue-43926.rs:11:20
    |
 LL | #[link(name="foo", cfg())] //~ ERROR `cfg()` must have an argument
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                    ^^^^^
 
 error: aborting due to previous error
 

src/test/ui/wasm-import-module.rs

@@ -8,13 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(wasm_import_module)]
-
-#[wasm_import_module] //~ ERROR: must be of the form
+#[link(name = "...", wasm_import_module)] //~ ERROR: must be of the form
 extern {}
 
-#[wasm_import_module = "foo"] //~ ERROR: must only be attached to
-fn foo() {}
+#[link(name = "...", wasm_import_module(x))] //~ ERROR: must be of the form
+extern {}
+
+#[link(name = "...", wasm_import_module())] //~ ERROR: must be of the form
+extern {}
 
 fn main() {}
 

src/test/ui/wasm-import-module.stderr

@@ -1,14 +1,20 @@
-error: must be of the form #[wasm_import_module = "..."]
-  --> $DIR/wasm-import-module.rs:13:1
+error: must be of the form #[link(wasm_import_module = "...")]
+  --> $DIR/wasm-import-module.rs:11:22
    |
-LL | #[wasm_import_module] //~ ERROR: must be of the form
-   | ^^^^^^^^^^^^^^^^^^^^^
+LL | #[link(name = "...", wasm_import_module)] //~ ERROR: must be of the form
+   |                      ^^^^^^^^^^^^^^^^^^
 
-error: must only be attached to foreign modules
-  --> $DIR/wasm-import-module.rs:16:1
+error: must be of the form #[link(wasm_import_module = "...")]
+  --> $DIR/wasm-import-module.rs:14:22
    |
-LL | #[wasm_import_module = "foo"] //~ ERROR: must only be attached to
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | #[link(name = "...", wasm_import_module(x))] //~ ERROR: must be of the form
+   |                      ^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: must be of the form #[link(wasm_import_module = "...")]
+  --> $DIR/wasm-import-module.rs:17:22
+   |
+LL | #[link(name = "...", wasm_import_module())] //~ ERROR: must be of the form
+   |                      ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors