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vec! macro should use with_capacity #17865

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thestinger opened this issue Oct 8, 2014 · 1 comment
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vec! macro should use with_capacity #17865

thestinger opened this issue Oct 8, 2014 · 1 comment
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A-macros Area: All kinds of macros (custom derive, macro_rules!, proc macros, ..) I-slow Issue: Problems and improvements with respect to performance of generated code.

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@thestinger
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There's no good reason for this doing vector reallocations.
@thestinger thestinger added I-slow Issue: Problems and improvements with respect to performance of generated code. A-macros Area: All kinds of macros (custom derive, macro_rules!, proc macros, ..) labels Oct 8, 2014
@japaric
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japaric commented Oct 8, 2014

There was a PR implementing this, but I think it was postponed until RFC #88 gets accepted.

cc @kballard

lnicola pushed a commit to lnicola/rust that referenced this issue Aug 13, 2024
@bors
Auto merge of rust-lang#17865 - ShoyuVanilla:exhaust-block, r=Veykril
0a336b3 
fix: Missing non-exhaustive let diagnostics inside async or unsafe block

The reason that this test doesn't have a pointer deref case is because the following code;
```rust
fn test(ptr: *const Result<i32, !>) {
    unsafe {
        let Ok(_x) = *ptr;
    }
}
```
is getting a block with no stmts but tail one in here(thus, no diagnostic error),
https://github.com/rust-lang/rust-analyzer/blob/0daeb5c0b05cfdf2101b0f078c27539099bf38e6/crates/hir-ty/src/diagnostics/expr.rs#L256-L257
while the following is getting a block with a single stmt without tail 🤔
```rust
fn test(x: Result<i32, &'static !>) {
    let Ok(_y) = x;
}
```
I'll make a more deep inspection and file this as a new issue

_Originally posted by `@ShoyuVanilla` in rust-lang/rust-analyzer#17853 (comment)
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A-macros Area: All kinds of macros (custom derive, macro_rules!, proc macros, ..) I-slow Issue: Problems and improvements with respect to performance of generated code.
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