[fpc-devel] Question on constref

[Michael Van Canneyt]

On Wed, 1 Feb 2023, Sven Barth via fpc-devel wrote:

> Am 01.02.2023 um 11:30 schrieb Bart via fpc-devel:
>> I thought that constref would be OK for that (the word constref
>> suggests to me tah the paramter will be treated (by me) to be a
>> constant, and that it shall be passed by reference in all cases,
>> whereas with a const parameter the compiler decides upon the best way
>> to pass it: by value or by reference).
>> I tried to find documentation for constref, but all I could find was:
>> https://wiki.freepascal.org/FPC_New_Features_2.6.0#Constref_parameter_modifier
>> There it says:
>> "Note that in general, it should only be used for interfacing with
>> external code or when writing assembler routines."
>
> “constref” is guaranteed to pass the parameter by reference. And the compiler 
> will ensure that it can't be modified as reasonably possible (as with “const” 
> there are ways to circumvent this, e.g. by passing around a pointer to the 
> parameter, but the general cases are covered).
>> (B.t.w.: Where can I find the official documentation on constref?)
>
> There is no full documentation for that parameter modifier (someone might 
> want to file a bug report for that), but the documentation for “const” ( 
> https://www.freepascal.org/docs-html/current/ref/refsu67.html#x183-20700014.4.4 
> ) contains this:

No need for a bugreport, this already is changed in trunk docs:

https://www.freepascal.org/daily/doc/ref/refsu68.html#x184-20800014.4.4

Michael.