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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Compiler checking of String lengths during assignment (Newbie
 Question)
Date: Fri, 09 Jan 2015 23:10:20 +0000
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isaac1.0@gmail.com writes:

> The first 2 cases produces an error during the build, as expected,
> because Head is known to be length of 5 and I'm assigning something of
> a different length.
> The 3rd assignment there does NOT produce an error, no warning no
> nothing even though this clearly violates the same check.
>
> What does happen is that at runtime the execution is incorrect. It
> doesn't even terminate in a horrible disaster (which would be
> preferable). The full program actually just reads a text file (for
> now) and in this case because the assigned length is incorrect, it
> just reads a few lines then bails claiming unable to read the text
> file.

This sounds as if it might be related to GCC PR ada/61466[1]. Are you
optimising?

> Aren't Ada compilers supposed to prevent stupid errors like this? Or
> is there some user stupidity here that I'm not seeing...?

Sometimes compilers do have bugs.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61466