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Walk the prototype chain looking for descriptors

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Looks like this breakage may occur in some scenarios so let's try to
future-proof ourselves!

Closes #109
This commit is contained in:
Alex Crichton 2018-04-09 06:16:41 -07:00
parent 9723fdd69b
commit a699455f03
1 changed files with 29 additions and 2 deletions
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31
crates/cli-support/src/js.rs
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@ -1080,6 +1080,31 @@ impl<'a> Context<'a> {
}
");
}
fn expose_get_inherited_descriptor(&mut self) {
if !self.exposed_globals.insert("get_inherited_descriptor") {
return
}
// It looks like while rare some browsers will move descriptors up the
// property chain which runs the risk of breaking wasm-bindgen-generated
// code because we're looking for precise descriptor functions rather
// than relying on the prototype chain like most "normal JS" projects
// do.
//
// As a result we have a small helper here which will walk the prototype
// chain looking for a descriptor. For some more information on this see
// #109
self.globals.push_str("
function GetOwnOrInheritedPropertyDescriptor(obj, id) {
while (obj) {
let desc = Object.getOwnPropertyDescriptor(obj, id);
if (desc) return desc;
obj = Object.getPrototypeOf(obj);
}
throw \"descriptor not found\";
}
");
}
}
impl<'a, 'b> SubContext<'a, 'b> {
@ -1447,8 +1472,9 @@ impl<'a, 'b> SubContext<'a, 'b> {
if import.structural {
format!("function() {{ return this.{}; }}", g)
} else {
self.cx.expose_get_inherited_descriptor();
format!(
"Object.getOwnPropertyDescriptor\
"GetOwnOrInheritedPropertyDescriptor\
({}.prototype, '{}').get;",
class,
g,
@ -1458,8 +1484,9 @@ impl<'a, 'b> SubContext<'a, 'b> {
if import.structural {
format!("function(y) {{ this.{} = y; }}", s)
} else {
self.cx.expose_get_inherited_descriptor();
format!(
"Object.getOwnPropertyDescriptor\
"GetOwnOrInheritedPropertyDescriptor\
({}.prototype, '{}').set;",
class,
s,