In C, double underscores should not be used at the start of an identifier

[seanm]

I notice there were some changes recently like:

cba993c

- static void H5_debug_mask(const char*);
+ static void H5__debug_mask(const char*);

Where some things got renamed to have double underscores.

However, in C, all names containing a double underscore are reserved:

https://wiki.sei.cmu.edu/confluence/display/cplusplus/DCL51-CPP.+Do+not+declare+or+define+a+reserved+identifier

These days clang can warn about that.

So really that change above is kinda backwards. :)

[qkoziol]

It's definitely "marching to our own drummer", at the least. :-)

The use of underscores after the "H5*" prefix for function names in the HDF5 source code follows these rules:

• Public routines: No '_' after the "H5*" prefix.
• "Library private"-scoped routines: One '_' after the "H5*" prefix.
• "Package"-scoped and static routines: Two '_' after the "H5*" prefix.

I believe our use of two '_' in package and static scoped function names predates the standard committee taking them away from user code. :-) I blame our non-compliance on the lack of namespace support in C. ;-)

I don't have an awesome suggestion to move away from using two '_' in the package and static scopes. I've tossed around various solutions and they mostly look awkward. :-/

[seanm]

Thanks for explaining the naming scheme, I understand the point of the change now.

More importantly, I confused C and C++, and in fact double underscore is OK within the identifier in C. Here's a link for C, not C++:

https://wiki.sei.cmu.edu/confluence/display/c/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier

But I didn't create this ticket for nothing, there are in fact many -Wreserved-id-macro warnings from clang.

A great many could be fixed by changing the include guard spelling:

#ifndef _H5ACmodule_H
#define _H5ACmodule_H

That could like be done with a regex.

[qkoziol]

Ah, excellent, glad to know that it's still OK in C. whew ;-)

Yes - I noticed the header file inclusion guard issue also and agree with you about fixing those.

[seanm]

What new spelling? Just drop the leading underscore?

[qkoziol]

Yes, that looks fine to me and is what the SEI page offers for a suggested fix.

[seanm]

OK cool. Seems sometimes 1 leading underscore is used, other times 2. These two regex seem to catch them all:

• _H5(.*)_H - 90 matches in .h files
• __H5(.*)_H - 501 matches in .h files

#361

[derobins]

Fixed in #361

[seanm]

Please reopen.

I just tried building from develop and there are still -Wreserved-id-macro warnings from include guards, for example:

hdf5/src/H5FDdevelop.h:19:9: warning: macro name is a reserved identifier [-Wreserved-id-macro]
#define _H5FDdevelop_H
        ^

I'll make a patch. But this will keep happening unless you add -Wreserved-id-macro to one of your buildbots... can you do that?

[seanm]

Additional fixes here: #1812