V2015 error_union_annotation_needed
Two different error unions meet in synthesis mode (for example the branches of an if).
An error from the type phase. sakura explain V2015 prints this explanation offline.
Two different error unions meet in synthesis mode (for example the branches of an if).
Annotate the binding or function with the union you mean (design §5.3).
Wrong program
compiler/tests/ui/V2015_error_union_annotation_needed.sakura, which the compiler's ui suite runs through sakura check:
error A
error B
fn fa() -> Int ! {Fail<A>} { fail A }
fn fb() -> Int ! {Fail<B>} { fail B }
fn pick(c: Bool) -> Unit { let _ = if c { try { fa() } } else { try { fb() } } }sakura check --json reports this record (pretty-printed; $DIR is the fixture's directory):
{
"schema_version": "1.0",
"kind": "diagnostic",
"id": "d:2d029aebf6a3e91f",
"code": "V2015",
"severity": "error",
"phase": "type",
"message": "expected `Result<Int, A>`, found `Result<Int, B>` (`B` is not `A`); annotate the binding with the joined error union",
"snapshot": "sha256:$SNAPSHOT",
"symbol_id": "main::V2015_error_union_annotation_needed::pick",
"spans": [
{
"uri": "file://$DIR/V2015_error_union_annotation_needed.sakura",
"content_hash": "sha256:2407ddc115dd635ed4832eb5bb83ac5ccdbf144d1035f9a18519a101d334e3e8",
"start_byte": 192,
"end_byte": 208,
"role": "primary",
"label": "this has type `Result<Int, B>`"
}
],
"related_ids": [],
"expected": {
"render": "Result<Int, A>"
},
"actual": {
"render": "Result<Int, B>"
},
"obligation": null,
"counterexample": null,
"explanation_uri": "sakura://explain/V2015",
"fixes": []
}Fixed program
compiler/tests/ui/V2015_error_union_annotation_needed.fixed.sakura, which sakura check accepts with no diagnostics:
error A
error B
fn fa() -> Int ! {Fail<A>} { fail A }
fn fb() -> Int ! {Fail<B>} { fail B }
fn pick(c: Bool) -> Unit { let _: Result<Int, A | B> = if c { try { fa() } } else { try { fb() } } }