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Stop passing -export-dynamic to wasm-ld.

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-export-dynamic was a temporary hack added in the early days of the Rust
wasm32 target when Rust didn't have a way to specify wasm exports in the
source code. This flag causes all global symbols, and some compiler-internal
symbols, to be exported, which is often more than needed.

Rust now does have a way to specify exports in the source code:
`#[export_name = "..."]`.

So as the original comment suggests, -export-dynamic can now be removed,
allowing users to have smaller binaries and better encapsulation in
their wasm32-unknown-unknown modules.

It's possible that this change will require existing wasm32-unknown-unknown
users will to add explicit `#[export_name = "..."]` directives to
exporrt the symbols that their programs depend on having exported.
This commit is contained in:
Dan Gohman 2022-12-06 16:50:29 -08:00
parent 53728ff751
commit 3a07aa9b5e
1 changed files with 0 additions and 7 deletions
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7
compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
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@ -33,12 +33,6 @@ pub fn target() -> Target {
// For now this target just never has an entry symbol no matter the output
// type, so unconditionally pass this.
"--no-entry",
// Rust really needs a way for users to specify exports and imports in
// the source code. --export-dynamic isn't the right tool for this job,
// however it does have the side effect of automatically exporting a lot
// of symbols, which approximates what people want when compiling for
// wasm32-unknown-unknown expect, so use it for now.
"--export-dynamic",
],
);
options.add_pre_link_args(
@ -48,7 +42,6 @@ pub fn target() -> Target {
// otherwise
"--target=wasm32-unknown-unknown",
"-Wl,--no-entry",
"-Wl,--export-dynamic",
],
);