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https://github.com/Mercury-Language/mercury.git
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2c1efdf543
Estimated hours taken: 1 Fix a bug reported by Ralph Becket which caused a compiler abort if the user declared the modes but not the types for a field access function. compiler/typecheck.m: In the clause introduced when the user declares the modes of a field access function, make sure the var-functor unification can only be interpreted as a field access, not a recursive function call. Add field labels to the typecheck_info type. tests/invalid/record_syntax_errors.m: tests/invalid/record_syntax_errors.err_exp: Add a test case. doc/reference_manual.texi: Clarify the documentation.
59 lines
1.4 KiB
Mathematica
59 lines
1.4 KiB
Mathematica
:- module record_syntax_errors.
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:- interface.
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:- type exist_cons
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---> some [T] exist_cons(field1::int, field2::T, field3::T).
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:- type cons
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---> cons(field4::int, field5::int, field6::cons2).
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:- type cons2
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---> cons2(field7::int, field8::int).
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:- pred dcg_syntax(cons::in, cons::out) is det.
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:- pred dcg_syntax_2(cons::in, cons::out) is det.
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:- pred dcg_type_error(cons::in, cons::out) is det.
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:- pred construct_exist_cons(exist_cons::out) is det.
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:- pred arg_type_error(cons::out) is det.
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:- mode field8(in) = out is det.
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:- implementation.
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dcg_syntax -->
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{ Field = field4 },
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^ Field := 1.
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dcg_syntax_2 -->
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X := Y.
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dcg_type_error -->
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^ field4 := 2.
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construct_exist_cons(ExistCons) :-
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ExistCons0 = 'new exist_cons'(1, 'b', 'c'),
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% This field cannot be updated because it shares
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% an existentially quantified type variable
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% with another field - updating the field changes
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% the type of the field.
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ExistCons = ExistCons0 ^ field2 := 1.
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arg_type_error(Cons) :-
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Cons0 = cons(1, 2, cons2(3, 4)),
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Cons = Cons0 ^ field6 ^ field7 := "invalid value".
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term_type_error(Cons) :-
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Cons0 = cons(1, 2, cons2(3, 4)),
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Cons = Cons0 ^ field6 ^ field4 := 1.
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% Check error message for local declarations for access functions
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% for exported fields.
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:- func field4(cons) = int.
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% Check error message for clauses for automatically generated access functions.
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field4(_) = 1.
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