Description of problem:
Generating a GIR (in my case with meson) started throwing the following error:

[49/50] Generating Modulemd-2.0.gir with a custom command.
/usr/include/glib-2.0/gobject/gobject.h:725: syntax error, unexpected ')' in '    ((__typeof__(new_object)) (g_object_ref) (new_object));' at ')'

A downgrade back to 1.58.0-2.fc29 works fine.


Version-Release number of selected component (if applicable):
gobject-introspection-1.58.1-1.fc29

How reproducible:
Every time

Steps to Reproduce:
1. `git clone https://github.com/fedora-modularity/libmodulemd.git`
3. `meson -D builddir`
4. `ninja -c builddir`

Actual results:
Files compile fine and the meson build completes successfully, but the error

[49/50] Generating Modulemd-2.0.gir with a custom command.
/usr/include/glib-2.0/gobject/gobject.h:725: syntax error, unexpected ')' in '    ((__typeof__(new_object)) (g_object_ref) (new_object));' at ')'

appears in the output. I can't determine yet if this has any negative impact on the resulting files (my tests still pass), but it's certainly alarming.

Expected results:
No warnings/errors reported.

Additional info: