Replace {Alloc,GlobalAlloc}::oom with a lang item. #50144
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mattico
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Apr 21, 2018
| name: "oom", | ||
| inputs: &[], | ||
| output: AllocatorTy::Bang, | ||
| }, |
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Nit: don't need AllocatorTy::Bang anymore
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@bors: r+ That was easier than I thought it would be! |
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📌 Commit b301d05 has been approved by |
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@bors r=alexcrichton |
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Replace {Alloc,GlobalAlloc}::oom with a lang item.
The decision of what to do after an allocation fails is orthogonal to the decision of how to allocate the memory, so this PR splits them apart. `Alloc::oom` and `GlobalAlloc::oom` have been removed, and a lang item has been added:
```rust
#[lang = "oom"]
fn oom() -> !;
```
It is specifically a weak lang item, like panic_fmt, except that it is required when you depend on liballoc rather than libcore. libstd provides an implementation that aborts with the message `fatal runtime error: memory allocation failed`, matching the current behavior.
The new implementation is also significantly simpler - it's "just another weak lang item". [RFC 2070](https://github.com/rust-lang/rfcs/blob/master/text/2070-panic-implementation.md) specifies a path towards stabilizing panic_fmt, so any complexities around stable weak lang item definition are already being solved.
To bootstrap, oom silently aborts in stage0. alloc_system no longer has a bunch of code to print to stderr, and alloc_jemalloc no longer depends on alloc_system to pull in that code.
One fun note: System's GlobalAlloc implementation didn't override the default implementation of oom, so it currently aborts silently!
r? @alexcrichton
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☀️ Test successful - status-appveyor, status-travis |
eddyb
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Apr 25, 2018
| @@ -59,7 +59,7 @@ unsafe impl<T> Alloc for T where T: CoreAlloc { | |||
| } | |||
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| fn oom(&mut self, _: AllocErr) -> ! { | |||
| CoreAlloc::oom(self) | |||
| unsafe { ::core::intrinsics::abort() } | |||
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Why doesn't this use the weak lang item?
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This is only used for stage0 I believe.
eddyb
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Apr 25, 2018
| @@ -303,7 +303,8 @@ language_item_table! { | |||
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| ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn; | |||
| BoxFreeFnLangItem, "box_free", box_free_fn; | |||
| DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn; | |||
| DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn; | |||
| OomLangItem, "oom", oom; | |||
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Are weak lang items not grouped in here?
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The decision of what to do after an allocation fails is orthogonal to the decision of how to allocate the memory, so this PR splits them apart.
Alloc::oomandGlobalAlloc::oomhave been removed, and a lang item has been added:It is specifically a weak lang item, like panic_fmt, except that it is required when you depend on liballoc rather than libcore. libstd provides an implementation that aborts with the message
fatal runtime error: memory allocation failed, matching the current behavior.The new implementation is also significantly simpler - it's "just another weak lang item". RFC 2070 specifies a path towards stabilizing panic_fmt, so any complexities around stable weak lang item definition are already being solved.
To bootstrap, oom silently aborts in stage0. alloc_system no longer has a bunch of code to print to stderr, and alloc_jemalloc no longer depends on alloc_system to pull in that code.
One fun note: System's GlobalAlloc implementation didn't override the default implementation of oom, so it currently aborts silently!
r? @alexcrichton