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internal: fix and force-disable block validation ;-( #10357

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Merged
merged 1 commit into from
Sep 26, 2021

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@matklad matklad commented Sep 26, 2021

Originally we tried to maintain the invariant that {} always match.
That is, that in the parse tree the pair of corresponding {} is always
first and last tokens of some nodes.

We had the code to validate that, but apparently it's been broken for
years since we introduced tokens/nodes split. Fixing it now makes
some tests fail.

It's unclear if we want to keep this invariant: there's a strong
motivation for breaking it in the following case:

use std::{ // unclosed paren

fn main() {

}

} // don't actually want to pair up this with the one from `use`

So let's fix the code, but disable it for the time being

bors r+
🤖

Originally we tried to maintain the invariant that `{}` always match.
That is, that in the parse tree the pair of corresponding `{}` is always
first and last tokens of some nodes.

We had the code to validate that, but apparently it's been broken for
**years** since we introduced tokens/nodes split. Fixing it now makes
some tests fail.

It's unclear if we want to keep this invariant: there's a strong
motivation for breaking it in the following case:

```
use std::{ // unclosed paren

fn main() {

}

} // don't actually want to pair up this with the one from `use`
```

So let's fix the code, but disable it for the time being
@bors
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bors bot commented Sep 26, 2021

@bors bors bot merged commit 0e3e3e2 into rust-lang:master Sep 26, 2021
matklad added a commit to matklad/rust-analyzer that referenced this pull request Sep 26, 2021
Consider these expples

        { 92 }
  async { 92 }
    'a: { 92 }
   #[a] { 92 }

Previously the tree for them were

  BLOCK_EXPR
    { ... }

  EFFECT_EXPR
    async
    BLOCK_EXPR
      { ... }

  EFFECT_EXPR
    'a:
    BLOCK_EXPR
      { ... }

  BLOCK_EXPR
    #[a]
    { ... }

As you see, it gets progressively worse :) The last two items are
especially odd. The last one even violates the balanced curleys
invariant we have (rust-lang#10357) The new approach is to say that the stuff in
`{}` is stmt_list, and the block is stmt_list + optional modifiers

  BLOCK_EXPR
    STMT_LIST
      { ... }

  BLOCK_EXPR
    async
    STMT_LIST
      { ... }

  BLOCK_EXPR
    'a:
    STMT_LIST
      { ... }

  BLOCK_EXPR
    #[a]
    STMT_LIST
      { ... }
matklad added a commit to matklad/rust-analyzer that referenced this pull request Sep 26, 2021
Consider these expples

        { 92 }
  async { 92 }
    'a: { 92 }
   #[a] { 92 }

Previously the tree for them were

  BLOCK_EXPR
    { ... }

  EFFECT_EXPR
    async
    BLOCK_EXPR
      { ... }

  EFFECT_EXPR
    'a:
    BLOCK_EXPR
      { ... }

  BLOCK_EXPR
    #[a]
    { ... }

As you see, it gets progressively worse :) The last two items are
especially odd. The last one even violates the balanced curleys
invariant we have (rust-lang#10357) The new approach is to say that the stuff in
`{}` is stmt_list, and the block is stmt_list + optional modifiers

  BLOCK_EXPR
    STMT_LIST
      { ... }

  BLOCK_EXPR
    async
    STMT_LIST
      { ... }

  BLOCK_EXPR
    'a:
    STMT_LIST
      { ... }

  BLOCK_EXPR
    #[a]
    STMT_LIST
      { ... }
matklad added a commit to matklad/rust-analyzer that referenced this pull request Sep 26, 2021
Consider these expples

        { 92 }
  async { 92 }
    'a: { 92 }
   #[a] { 92 }

Previously the tree for them were

  BLOCK_EXPR
    { ... }

  EFFECT_EXPR
    async
    BLOCK_EXPR
      { ... }

  EFFECT_EXPR
    'a:
    BLOCK_EXPR
      { ... }

  BLOCK_EXPR
    #[a]
    { ... }

As you see, it gets progressively worse :) The last two items are
especially odd. The last one even violates the balanced curleys
invariant we have (rust-lang#10357) The new approach is to say that the stuff in
`{}` is stmt_list, and the block is stmt_list + optional modifiers

  BLOCK_EXPR
    STMT_LIST
      { ... }

  BLOCK_EXPR
    async
    STMT_LIST
      { ... }

  BLOCK_EXPR
    'a:
    STMT_LIST
      { ... }

  BLOCK_EXPR
    #[a]
    STMT_LIST
      { ... }
matklad added a commit to matklad/rust-analyzer that referenced this pull request Sep 26, 2021
Consider these expples

        { 92 }
  async { 92 }
    'a: { 92 }
   #[a] { 92 }

Previously the tree for them were

  BLOCK_EXPR
    { ... }

  EFFECT_EXPR
    async
    BLOCK_EXPR
      { ... }

  EFFECT_EXPR
    'a:
    BLOCK_EXPR
      { ... }

  BLOCK_EXPR
    #[a]
    { ... }

As you see, it gets progressively worse :) The last two items are
especially odd. The last one even violates the balanced curleys
invariant we have (rust-lang#10357) The new approach is to say that the stuff in
`{}` is stmt_list, and the block is stmt_list + optional modifiers

  BLOCK_EXPR
    STMT_LIST
      { ... }

  BLOCK_EXPR
    async
    STMT_LIST
      { ... }

  BLOCK_EXPR
    'a:
    STMT_LIST
      { ... }

  BLOCK_EXPR
    #[a]
    STMT_LIST
      { ... }
This was referenced Oct 10, 2021
bors bot added a commit that referenced this pull request Oct 10, 2021
10506: Add comment r=lnicola a=k-nasa

## Why


This code looks logic-bug ...


https://github.com/rust-analyzer/rust-analyzer/blob/ce86534e1cb22685e83c3f91ea89025edbfcbc98/crates/syntax/src/syntax_node.rs#L50


However, this code has been intentionally disabled.
It's a good idea to write a comment

ref: #10357

## What

- I added comment

Co-authored-by: k-nasa <[email protected]>
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