a61685772d
A closure literal whose body raises but is annotated non-failable (or has no ! in its return) now gets a lambda-specific diagnostic telling the user to declare the failable return explicitly, instead of the generic "raise is only valid inside a failable function". Failability is never inferred for a lambda, so a raising lambda with no ! is a hard error that should point at the fix. New in_lambda_body flag (save/restore for nesting) set around the lambda body lowering in lowerLambda; diagRaiseNotFailable branches on it. Top-level functions keep the generic message. Test: 1043-errors-lambda-raise-annotation-hint.sx.
21 lines
930 B
Plaintext
21 lines
930 B
Plaintext
// A closure literal whose body `raise`s but is annotated non-failable (or has
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// no `!` in its return) gets a LAMBDA-SPECIFIC diagnostic telling the user to
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// declare the failable return explicitly (ERR E5.1 sub-feature 1). This is the
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// closure analog of the top-level "raise is only valid inside a failable
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// function" error — failability is never inferred for a lambda, it must be
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// declared, so a raising lambda with no `!` is a hard error pointing at the fix.
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#import "modules/std.sx";
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E :: error { Neg }
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take :: (cb: Closure(s32) -> (s32, !E), x: s32) -> s32 { return cb(x) catch e -1; }
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main :: () -> s32 {
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// `-> s32` (non-failable) but the body raises → lambda-specific hint:
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// "lambda body raises; declare its return type explicitly with
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// `-> (T, !)` or `-> (T, !Named)`"
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print("{}\n", take(closure((x: s32) -> s32 { if x < 0 { raise error.Neg; } return x; }), -1));
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return 0;
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}
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