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[Sebastian]

Hello,

checkmate seems to overlook full-array assignments to not-allocated arrays. There's no problem with assigning only a single element (or a range) which is correctly claimed as invalid operation when using checkmate.

Sample:

[PaulLaidler]

We will take a look at this to see if the error can be trapped.

[Sebastian]

Thanks.

Do you happen to know if it is actually an error (coding bug) or should a
full-array assignment just be ignored by the compiler if the array is not
allocated yet? The latter would make sense if the full-array alloc is something
like "initialize all elements" where elements==0 for unallocated arrays.

[PaulLaidler]

It is a programming error but it would be nice if checkmate was clever enough to flag it.

[PaulLaidler]

We have investigated this matter to see if checkmate can be extended to check for this programming error. Unfortunately this is not possible without endangering other parts of the compiler. In other words the undef check works for individual elements but not for block assignment and we cannot see a way to improve on this.

What happens is the compiler expands the block assignment into a loop but the loop is never entered because the default size is negative. As a result the built-in test on individual elements is never applied.

In practice the fault will become apparent when you try to access the array values.

[Sebastian]

[PaulLaidler]

I do understand where the fault occurs but, as you pointed out, the impact of the programming error may occur later.

In theory the default value of the size (of an unallocated array) is undefined.
You cannot rely on its value either from one compiler to another or even within FTN95 from one release to another.

[Sebastian]