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2e814a7b22
An exhaustive `when` expression (one with no explicit `else` that the
compiler proves total) gets a synthetic `throw NoWhenBranchMatchedException(...)`
as its fallback branch. The two frontends locate that synthetic call
differently:
* K2 gives the call the source offsets of the enclosing `when`
expression, so the throw (and the `new NoWhenBranchMatchedException`)
are located at the `when` block, e.g. `6:3:9:3`.
* K1 leaves the synthetic call with undefined offsets, so the extractor
emits a `0:0:0:0` (no-source) location for both nodes.
A real source location is strictly more useful than none, and anchoring
the implicit fallback to the `when` it belongs to is the intuitive
choice, so we adopt the K2 behaviour for both frontends.
`extractCall` now records the enclosing `when`'s location while
extracting its branches (`currentSyntheticWhenLocation`) and uses it as
the fallback for the `noWhenBranchMatchedException` builtin whenever the
synthetic call itself has undefined offsets. This only changes K1: under
K2 the call already carries valid offsets, so `tw.getLocation(c)` is used
unchanged and K2 output is byte-identical.
Relearned both suites: all 3333 tests pass and the only changed row is
test-kotlin1/library-tests/no-when-branch-found, which now matches
test-kotlin2 exactly (`0:0:0:0` -> `6:3:9:3`).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>