Incorrect highlighting of parse errors in else body #14784
Description
Describe the bug
When the else body of an if expression has a parse error, the wrong span is highlighted in red. In fact, it seems like only the last span is highlighted in red, no matter what.
How to reproduce
You can trigger this issue by typing if true { 0 } else echo <bad expr>... <good expr> into the REPL. <bad expr>... is one or more expressions with parse errors in them (e.g. $nonexistent or ([] + "foo"), separated by spaces. <good expr> is something without any parse, e.g. 2.
Only the last span, <good expr>, will be highlighted red, and there will be no highlighting for the stuff before it (echo <bad expr>...) at all.
For example, you can use if true { 0 } else echo $foo 2. The 2 is highlighted rather than $foo, the nonexistent variable.
It looks like when the parser realizes that $foo is undefined, instead of creating a garbage span for $foo, it creates one for 2.
> ast -f "if true { 0 } else echo $foo 2"
╭─#─┬─content─┬───────shape────────┬──────span──────╮
│ 0 │ if │ shape_internalcall │ ╭───────┬───╮ │
│ │ │ │ │ start │ 0 │ │
│ │ │ │ │ end │ 2 │ │
│ │ │ │ ╰───────┴───╯ │
│ 1 │ true │ shape_bool │ ╭───────┬───╮ │
│ │ │ │ │ start │ 3 │ │
│ │ │ │ │ end │ 7 │ │
│ │ │ │ ╰───────┴───╯ │
│ 2 │ { │ shape_block │ ╭───────┬────╮ │
│ │ │ │ │ start │ 8 │ │
│ │ │ │ │ end │ 10 │ │
│ │ │ │ ╰───────┴────╯ │
│ 3 │ 0 │ shape_int │ ╭───────┬────╮ │
│ │ │ │ │ start │ 10 │ │
│ │ │ │ │ end │ 11 │ │
│ │ │ │ ╰───────┴────╯ │
│ 4 │ } │ shape_block │ ╭───────┬────╮ │
│ │ │ │ │ start │ 11 │ │
│ │ │ │ │ end │ 13 │ │
│ │ │ │ ╰───────┴────╯ │
│ 5 │ else │ shape_keyword │ ╭───────┬────╮ │
│ │ │ │ │ start │ 14 │ │
│ │ │ │ │ end │ 18 │ │
│ │ │ │ ╰───────┴────╯ │
│ 6 │ 2 │ shape_garbage │ ╭───────┬────╮ │
│ │ │ │ │ start │ 29 │ │
│ │ │ │ │ end │ 30 │ │
│ │ │ │ ╰───────┴────╯ │
╰───┴─────────┴────────────────────┴────────────────╯
Expected behavior
I would expect the span for $foo to be highlighted red, nothing else. I would also expect both echo and 2 to be highlighted normally, although that's not as much of a priority.
Configuration
| key | value |
|---|---|
| version | 0.101.0 |
| major | 0 |
| minor | 101 |
| patch | 0 |
| branch | |
| commit_hash | |
| build_os | linux-x86_64 |
| build_target | x86_64-unknown-linux-gnu |
| rust_version | rustc 1.83.0 (90b35a623 2024-11-26) (built from a source tarball) |
| cargo_version | cargo 1.83.0 (5ffbef321 2024-10-29) |
| build_time | 1980-01-01 00:00:00 +00:00 |
| build_rust_channel | release |
| allocator | mimalloc |
| features | default, sqlite, trash |
| installed_plugins |