starter text for declspec description

[naughtont3]

Signed-off-by: Thomas Naughton naughtont@ornl.gov

[naughtont3]

@jjhursey @jsquyres I started to jot this down during meeting today and then figured I'd go ahead and just try adding the paragraph. Much room for improvement, but maybe provides a spot for other ticket to document the current "expectations" for use of DECLSPEC.

[jsquyres]

@naughtont3 You may want to look at:

• https://docs.open-mpi.org/en/main/developers/sphinx.html#install-sphinx-in-a-python-virtual-environment
• https://docs.open-mpi.org/en/main/developers/rst-for-markdown-expats.html

[naughtont3]

@jsquyres Thanks for feedback. BTW, was the delineation for the DECLSPEC/MODULE_DECLSPEC accurate as to your understanding? Just want to double check myself.

[jsquyres]

@naughtont3 Do you want to add this content to the docs/developer/source-code.rst file in #10772?

[jsquyres]

Suggested change

	(e.g., `libmpi.so`).
	(e.g., ``libmpi.so``).

[jsquyres]

Suggested change

	The ``*_DECLSPEC`` attribute is used to declare that the developer wants a
	symbol to be usable outside of that library/DSO. For example,
	The ``*_DECLSPEC`` attributes are used to declare that a
	symbol is to be visible outside of that library/DSO's scope. For example,

[jsquyres]

Nit: extra blank line at the end of the file.

[jsquyres]

Looking at the code today, I wonder if the MODULE_DECLSPEC is left over from when we supported Windows. Today, DECLSPEC and MODULE_DECLSPEC resolve to the same back-end compiler attribute. I have a super-dim recollection that they might have been different on Windows, and we therefore needed 2 different macros.

But since we've long-since stopped supporting Windows, should we ditch the MODULE_DECLSPEC macro?

[jjhursey]

👍 for removing MODULE_DECLSPEC if it is redundant.

[jsquyres]

I just checked Open MPI v1.0.0, and I confirm: in Windows, there was a difference between exporting the component symbol and exporting other symbols.

Given that we don't support native Windows builds any more, I think we should remove the distinction.

@naughtont3 I can make a PR for the code change if you want to update the text.

[jsquyres]

PR to remove MODULE_DECLSPEC: #10774

[jjhursey]

The text looks good to me. Thanks for writing this up!

[naughtont3]

@naughtont3 Do you want to add this content to the docs/developer/source-code.rst file in #10772?

@jsquyres Yes, it seems like that is better spot. I'll roll rest of your feedback into this PR to include the elimination of MODULE_DECLSPEC bits. Do you just want me to open a PR on #10772?

[naughtont3]

@jsquyres I create jsquyres#11 and we can just close this item once things are rolled into #10722.

[jsquyres]

This PR has been made moot by #10780