Is it true that conventional build systems make the assumption that if the contents of a source file doesn't change, and other compiler flags and dependencies stay the same, then there is no need for rebuild?

If that assumption is true, is there a concern that it will get invalidated when arbitrary side effects are allowed to change the conceptual contents (as generated by static code generation) of a given source file? If yes, what is the new build model? If not, how are we sure of that?

-- Gaby



________________________________
From: SG15 <sg15-bounces_at_[hidden]> on behalf of Matthias Kretz via SG15 <sg15_at_[hidden]>
Sent: Friday, October 25, 2024 3:12:24 AM
To: sg15_at_[hidden] <sg15_at_[hidden]ocpp.org>
Cc: Matthias Kretz <m.kretz_at_[hidden]>
Subject: Re: [isocpp-sg15] [P2758] Emitting messages at compile time

On Friday, 25 October 2024 07:55:51 GMT+2 Corentin via SG15 wrote:
> > So that no good deed goes unpunished 😊 I'll warn you that I intend to be
> > greedy: Some of us will be asking for general compile-time I/O, or at
> > least
> > O (output), in a consteval function. For example […]
>
> None of the novel reflection features have deployment experience and a lot
> of that hasn't been implemented. […]
> Maybe we can take it one step at a time?

I agree and disagree. The important point Herb is making is that these
features are related. Consequently, it is useful to keep the bigger picture in
mind while working on one aspect of compile-time I/O.

Regarding additional output files from compilers: This isn't novel. What is
novel is that the C++ source gets more say in the content of such files. I
believe file paths would typically be set via compiler flags anyway. In that
case it's still on the radar of the build system what's going on.

--
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 std::simd
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