Enables cross-compiling

[randall]

These changes allow for CompileParseRules to be built and run on host
architecture along with cleaning up automake macros that previously
prevented cross-compilation

[randall]

my testing consisted of cross-compiling on x86_64 macOS targeting arm64.

To test targeting arm64 macOS on x86_64 host, you'll need to build OpenSSL and PCRE (at minimum). I installed my dependencies under /opt/arm64

For PCRE:

CFLAGS='-target arm64-apple-macos'; export CFLAGS
CPPFLAGS='-target arm64-apple-macos'; export CPPFLAGS
CXXFLAGS='-target arm64-apple-macos'; export CXXFLAGS
LDFLAGS='-target arm64-apple-macos'; export LDFLAGS
CC=clang; export CC
CXX=clang++; export CXX
./configure \
--prefix=/opt/arm64 \
--host=x86_64-apple-darwin \
--disable-dependency-tracking \
--disable-silent-rules \
--disable-cpp \
--enable-shared=no
make && make install

For OpenSSL:

./Configure --prefix=/opt/arm64 darwin64-arm64-cc 
make && make install

The environment vars I set along with the host value in testing:

CFLAGS='-target arm64-apple-macos'; export CFLAGS
CXXFLAGS='-target arm64-apple-macos'; export CXXFLAGS
CPPFLAGS="-target arm64-apple-macos -I/opt/arm64/include"; export CPPFLAGS
LDFLAGS="-target arm64-apple-macos -L/opt/arm64/lib"; export LDFLAGS
AM_LDFLAGS="-Xcompiler -target -Xcompiler arm64-apple-macos"; export AM_LDFLAGS
CC=clang; export CC
CXX=clang++; export CXX
./configure \
--host=x86_64-apple-darwin \
--with-openssl=/opt/arm64 \
--with-pcre=/opt/arm64

(I'm not saying those are required, I just tested with those).

This might've addressed some of the issues described in #7754

[bryancall]

I am getting this error when running configure:

configure:7756: checking whether the C compiler works
configure:7778: clang -target arm64-apple-macos -target arm64-apple-macos -I/opt/arm64/include -target arm64-apple-macos -L/opt/arm64/lib conftest.c  >&5
ld: warning: directory not found for option '-L/opt/arm64/lib'
ld: warning: ignoring file /Library/Developer/CommandLineTools/usr/lib/clang/11.0.0/lib/darwin/libclang_rt.osx.a, missing required architecture arm64 in file /Library/Developer/CommandLineTools/usr/lib/clang/11.0.0/lib/darwin/libclang_rt.osx.a (3 slices)
ld: warning: ignoring file /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib/libSystem.tbd, missing required architecture arm64 in file /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib/libSystem.tbd
ld: dynamic main executables must link with libSystem.dylib for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
configure:7782: $? = 1
configure:7822: result: no
configure: failed program was:
| /* confdefs.h */
| #define PACKAGE_NAME "Apache Traffic Server"
| #define PACKAGE_TARNAME "trafficserver"
| #define PACKAGE_VERSION "10.0.0"
| #define PACKAGE_STRING "Apache Traffic Server 10.0.0"
| #define PACKAGE_BUGREPORT "dev@trafficserver.apache.org"
| #define PACKAGE_URL "https://trafficserver.apache.org"
| #define PACKAGE "trafficserver"
| #define VERSION "10.0.0"
| #define HAS_CURL 1
| /* end confdefs.h.  */
|
| int
| main (void)
| {
|
|   ;
|   return 0;
| }
configure:7827: error: in `/Users/bcall/dev/apache/trafficserver/build-Darwin':
configure:7829: error: C compiler cannot create executables
See `config.log' for more details

[bryancall]

I will take a look at this again.

[SolidWallOfCode]

Any reason for the trailing "dnl"?

[randall]

That's what's in the upstream repo.

http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_cc_for_build.m4

[SolidWallOfCode]

This builds cleanly for me.

[randall]

[approve ci]

[zwoop]

Cherry-picked to v9.2.x