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Re: [Tooling] [isocpp-modules] Round2: Path to modules with old bad build systems

From: Mathias Stearn <redbeard0531+isocpp_at_[hidden]>
Date: Tue, 5 Mar 2019 15:47:16 -0500
On Tue, Mar 5, 2019 at 2:32 PM Gabriel Dos Reis via Modules <
modules_at_[hidden]> wrote:

> Specifically, I don't understand why the compiler would go through the
> troubles of emitting something like that when it would be simpler to just
> supply the switch -ftreat-imports-as-glorified-headers. The sources could
> still be preprocessed and retain the imports, etc.

When you pass -ftreat-imports-as-glorified-headers, can also tell the
compiler to just preprocess[1], then take just the output from that and
hand it to the compiler again to have it translated to an object file and
have it behave the same as if it was working with the original files? If
so, then I think we are just using different terms for the same thing. If
not, can you explain what is different?

[1] Currently, with gcc and clang, you need to "partially preprocess" using
-fdirectives-only or -frewrite-includes because those tools behave
differently when compiling TUs that have already been fully preprocessed. I
haven't tried doing a similar experiment with MSVC to know how well it
handles fully preprocessed files.

Received on 2019-03-05 21:47:29