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Re: [PING^2] ada: Add limitations on the acceptable prefixes of 'Old
On 7/05, Samuel Tardieu wrote:
| Legality rules preventing "out" parameters to be read before they are
| initialized do not exist because some cases would be undecidable. So
| reading "out" parameters is legal, and the compiler cannot do anything
| but warn about it even if it knows it is incorrect in some cases. But
| here, taking 'Old on an "out" parameter always refers to an uninitialized
| variable and can never be correct. This is why I think it deserves a
| legality rule, as simple as "'Old cannot be applied to OUT mode
| parameters".
I withdraw this one, as we might end up with 'Old being applied to an
expression (such as a function call) referring to an out mode parameter
anyway.
But I'm still in favour of keeping item 4 (formal default expression).