Explicitly define used NIF symbols #792
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We ran into an issue with the new Xcode version 14 command line tools,
version 2395.
The linker gave a warning about `dynamic_lookup` not working with
chained fixups, a thing that is now enabled by default on the command
line tools looks like.
```
ld: warning: -undefined dynamic_lookup may not work with chained fixups
```
It looks like we can't use `dynamic_lookup`. Instead define a list
ourselves of all the symbols we use in the `c_src/appsignal_extension.c`
file. That way we tell the linker to ignore the undefined symbols, and
have them be looked up at runtime when the Elixir NIF library is loaded.
Every time we call another NIF function defined in `erl_nif.h` we need
to update this list.
## ld documentation changes between Xcode versions that broke
Xcode Version 13.4.1 (13F100), from macOS 12.5:
```
$ man ld
-undefined treatment
Specifies how undefined symbols are to be treated. Options
are: error, warning, suppress, or dynamic_lookup. The
default is error.
```
New Xcode Version 14.0 (14A309), from macOS 12.6:
```
$ man ld
-undefined treatment
Specifies how undefined symbols are to be treated. Options
are: error, warning, suppress, or dynamic_lookup. The
default is error. Note: dynamic_lookup that depends on lazy
binding will not work with chained fixups.
-U symbol_name
Specified that it is ok for symbol_name to have no
definition. With -two_levelnamespace, the resulting symbol
will be marked dynamic_lookup which means dyld will search
all loaded images.
```
Closes #790
Co-authored-by: Jeff Kreeftmeijer <jeffkreeftmeijer@gmail.com>
unflxw
approved these changes
Sep 15, 2022
luismiramirez
approved these changes
Sep 15, 2022
This was referenced Sep 15, 2022
tombruijn
added a commit
that referenced
this pull request
Sep 15, 2022
We made a mistake in PR #792. We split up the very long line in the Makefile to specify a symbol per line. This accidentally broke how the linker interprets these options. Specify the symbols per line, but on each line also include the `-Wl,` prefix to specify the liker option. Somehow the multi line option value for `-Wl,` didn't work.
tombruijn
added a commit
that referenced
this pull request
Sep 15, 2022
We made a mistake in PR #792. We split up the very long line in the Makefile to specify a symbol per line. This accidentally broke how the linker interprets these options. Specify the symbols per line, but on each line also include the `-Wl,` prefix to specify the liker option. Somehow the multi line option value for `-Wl,` didn't work.
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We ran into an issue with the new Xcode version 14 command line tools, version 2395.
The linker gave a warning about
dynamic_lookupnot working with chained fixups, a thing that is now enabled by default on the command line tools looks like.It looks like we can't use
dynamic_lookup. Instead define a list ourselves of all the symbols we use in thec_src/appsignal_extension.cfile. That way we tell the linker to ignore the undefined symbols, and have them be looked up at runtime when the Elixir NIF library is loaded. Every time we call another NIF function defined inerl_nif.hwe need to update this list.ld documentation changes between Xcode versions that broke
Xcode Version 13.4.1 (13F100), from macOS 12.5:
New Xcode Version 14.0 (14A309), from macOS 12.6:
Closes #790
Co-authored-by: Jeff Kreeftmeijer jeffkreeftmeijer@gmail.com