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ef0328837f
In FunC (and in Tolk before) throwing an exception is just
calling a built-in function:
> throw 123; // actually, __throw(123)
Since it's a regular function, the compiler was not aware
that execution will stop, and all following code is unreachable.
For instance, `throw` in the end on function needed to be
followed by `return` statement.
Now, `throw` interrupts control flow, all statements after
it are considered unreachable. At IR level, code Ops are
also not produced.
This works because a built-in __throw() now has `never` type.
It can also be applied to custom functions:
> fun alwaysThrow(): never { throw 123; }
The code after alwaysThrow() call will also be unreachable.
24 lines
356 B
Text
24 lines
356 B
Text
fun alwaysThrows(): never {
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throw 456;
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}
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fun testUnreachable(x: int) {
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if (x) { throw 123; }
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else { alwaysThrows(); }
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return 1;
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}
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fun main() {
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try {
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testUnreachable(100);
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throw 80;
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} catch (excNo) {
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return excNo;
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}
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}
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/**
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@testcase | 0 | | 123
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@stderr warning: unreachable code
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@stderr return 1;
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*/
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