v.ast, v.checker: fix infinite loops and segfaults in generic instantiation and cyclic aliases #28005
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,96 @@ | ||
| fn generic_level_1[T](val T) T { | ||
| return val | ||
| } | ||
|
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| fn generic_level_2[T](val T) T { | ||
| return generic_level_1[T](val) | ||
| } | ||
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| fn generic_level_3[T](val T) T { | ||
| return generic_level_2[T](val) | ||
| } | ||
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| fn generic_level_4[T](val T) T { | ||
| return generic_level_3[T](val) | ||
| } | ||
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| fn test_valid_nested_generic_functions() { | ||
| res_int := generic_level_4[int](42) | ||
| assert res_int == 42 | ||
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| res_str := generic_level_4[string]('Vlang') | ||
| assert res_str == 'Vlang' | ||
| } | ||
|
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| struct Box[T] { | ||
| pub: | ||
| val T | ||
| } | ||
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| fn test_valid_nested_generic_structs() { | ||
| b1 := Box[int]{ | ||
| val: 100 | ||
| } | ||
| b2 := Box[Box[int]]{ | ||
| val: b1 | ||
| } | ||
| b3 := Box[Box[Box[int]]]{ | ||
| val: b2 | ||
| } | ||
| b4 := Box[Box[Box[Box[int]]]]{ | ||
| val: b3 | ||
| } | ||
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| assert b4.val.val.val.val == 100 | ||
| } | ||
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| type Alias1 = int | ||
| type Alias2 = Alias1 | ||
| type Alias3 = Alias2 | ||
| type Alias4 = Alias3 | ||
| type Alias5 = Alias4 | ||
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| fn test_valid_type_alias_chain() { | ||
| mut num := Alias5(10) | ||
| assert num == Alias5(10) | ||
|
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| num += Alias5(20) | ||
| assert num == Alias5(30) | ||
| } | ||
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| struct Some[T] { | ||
| pub: | ||
| val T | ||
| } | ||
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| struct None {} | ||
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| type MyOption[T] = None | Some[T] | ||
| type ComplexResult[T, E] = E | Some[T] | ||
|
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| fn test_valid_generic_sum_types() { | ||
| opt_some := MyOption[int](Some[int]{ | ||
| val: 99 | ||
| }) | ||
| if opt_some is Some[int] { | ||
| assert opt_some.val == 99 | ||
| } else { | ||
| assert false | ||
| } | ||
|
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| opt_none := MyOption[string](None{}) | ||
| if opt_none is None { | ||
| assert true | ||
| } else { | ||
| assert false | ||
| } | ||
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| res := ComplexResult[int, string](Some[int]{ | ||
| val: 500 | ||
| }) | ||
| if res is Some[int] { | ||
| assert res.val == 500 | ||
| } else { | ||
| assert false | ||
| } | ||
| } |
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A finite generic instantiation can exceed 1,024 bytes without containing a cycle—for example, a generated generic with many concrete parameters or nested qualified type names—yet it now unconditionally panics here. Because V does not otherwise impose this identifier-length restriction, valid source that previously compiled now crashes; recursion should be bounded by the instantiation graph rather than the rendered name length.
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