[SR-328] Some Glibc functions not imported because they depend on feature test macros

[swift-ci]

Previous ID	SR-328
Radar	None
Original Reporter	dunkelstern (JIRA User)
Type	Bug

Environment

Ubuntu 15.10

Additional Detail from JIRA

Votes	1
Component/s	Compiler, Standard Library
Labels	Bug, ClangImporter, Linux
Assignee	None
Priority	Medium

md5: fe85e3a129e976d855f0176e874a827d

Issue Description:

Try using strptime or lrand48 for example, they need the C compiler macro _XOPEN_SOURCE defined to work.

see: man 7 feature_test_macros for further examples

[swift-ci]

Comment by Johannes Schriewer (JIRA)

Ping @ddunbar @belkadan can we expect this to be fixed in the near future? It is just missing a #define _GNU_SOURCE somewhere. I had a ugly-hack workaround: I just created a big header file with that define at the beginning and all headers from the Glibc.modulemap included.

Shall I create something in that fashion and PR it or has this no chance beeing included?

[belkadan]

I think we'd accept a PR to change the Clang importer itself. It has a bunch of predefines on OS X; can't see why doing some for Linux would be a problem. I'd want someone else to review and agree that the settings you pick make sense as Swift's defaults, though.

(You can work around this using -Xcc, which passes arguments through to the Clang inside Swift.)

[gparker42]

This change was again proposed as part of Fuschia OS support.
#12955

One way or the other it will likely be changed soon.