Hi Everyone,
I'm testing on an Intel Mac-mini with OS X 10.12. The machine is modern and has Apple Clang 9.0.0 (Apple versioning does not follow LLVM versioning).
GnuPG is a little dirty on its compile. But the reason for the bug report is, some of the items look non-trivial:
I think each source file produces a warning for `-fno-delete-null-pointer-checks`:
```
libtool: compile: /usr/bin/clang -DHAVE_CONFIG_H -I. -I.. -I../src -I../src -I/Users/jwalton/ok2delete/include -I/Users/jwalton/ok2delete/include -DNDEBUG -g2 -O2 -fno-common -march=native -fPIC -pthread -fno-delete-null-pointer-checks -Wall -MT compat.lo -MD -MP -MF .deps/compat.Tpo -c compat.c -fno-common -DPIC -o .libs/compat.o
clang: warning: optimization flag '-fno-delete-null-pointer-checks' is not supported [-Wignored-optimization-argument]
```
And this one looks suspicious, too:
```
libtool: compile: /usr/bin/clang -DHAVE_CONFIG_H -I. -I.. -I../src -I../src -I/Users/jwalton/ok2delete/include -DNDEBUG -I/Users/jwalton/ok2delete/include -g2 -O0 -fno-common -march=native -fPIC -pthread -fno-delete-null-pointer-checks -Wall -c ./rndjent.c -fno-common -DPIC -o .libs/rndjent.o
clang: warning: optimization flag '-fno-delete-null-pointer-checks' is not supported [-Wignored-optimization-argument]
In file included from ./rndjent.c:86:
./jitterentropy-base.c:53:13: warning: unknown pragma ignored
[-Wunknown-pragmas]
#pragma GCC optimize ("O0")
^
```
For the optimization issue, I believe a better choice would be... modify the makefile recipe for `rndjent.c` and always apply `-O0`, `-zO0`, etc. According to the GNU Make manual, you are allowed to apply flags that are necessary to compile the source file. (This is not a case of ignoring a user's choice if -O0 is required).
So the recipe might look something like this. Autoconf would determine the flag to use for `NO_OPT`.
```
rndjent.o:
$(CC) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) $(NO_OPT) -c rndjent.c -o rndjent.o
```