This PR began as an attempt to drop GCC support, after repeated reports
on fallouts when trying to use it on macOS.
Then it transformed into a 3-week project turning up the issues causing
the fallouts, ending up including llvm and all available Xcode / macOS
SDK, macOS runner image, build tools and compiler vendors and versions.
Accumulating 400 sub-commits.
I developed and tested all fixes under this PR, then merged them as
separate patches.
This PR retained CI jobs updates, extensively reworking and extending
them: [1]
At first it seemed GCC and the Apple SDK is "naturally" growing more
incompatible, as Apple added further non-standard features to their
headers. This is partly true, but reality is more complicated.
Besides some issues local to curl, there were bugs in Apple SDK
headers, Homebrew GCC builds, feature missing in the old llvm version
pre-installed on GitHub CI runner images, and subtle incompatibilities
between GCC and llvm/clang when handling language extensions.
Resulting compiler errors seldom pointed to a useful direction, and
internet search was silent about these issues too. Thus, I had to peel
them off layer by layer, using trial and error, and by recognizing
patterns of failures accross 150-200 builds combinations. Exposing
configure logs, and curl_config.h in the CI logs helped too.
1. GCC header compatibility layer ("hack" as GCC calls it)
The toughest issue is GCC's built-in compatibility layer:
https://github.com/gcc-mirror/gcc/tree/master/fixincludes
This patch layer is further patched by a "Darwin compatibility" project
applied on top by Homebrew GCC via:
https://github.com/iains/gcc-12-branchhttps://github.com/iains/gcc-13-branchhttps://github.com/iains/gcc-14-branch
The hack layer is designed in a way that breaks more builds than it
fixes, esp. in context of GHA runners. The idea is to build GCC
specifically for the SDK for the target macOS version. The problem with
this approach is that the Xcode + SDK installed on the local/CI machine
often does not match with the SDK used on while building GCC on
Homebrew's build machines. In these cases the GCC compatibility layer
turns into an "uncompatibility" layer and consistently breaks builds.
curl cannot offer a fix for this, because the solution (I found) is to
patch the toolchain on the local machine. I implemented this for our CI
builds and curl-for-win. In other case the user must do this patching
manually, or choose a compatible GCC + Xcode/SDK combination.
An upstream fix doesn't seem trivial either, because the issue is
ingrained in the compatibility layer's design. Offering an `-fapplesdk`
(or recognizing `-target`) option and/or fixing them within the compiler
would seem like a more robust option, and also how mainline llvm solves
this.
Here's a table summarizing the GCC + SDK combinations and curl build
failures: [2]
More info: https://github.com/curl/curl/issues/10356#issuecomment-2222734103db135f8d72#14119 macos: add workaround for gcc, non-c-ares, IPv6, compile error
Ref: e2db3c475f
Ref: f5c58d7fef
2. Homebrew GCC's `availability` extension
A recent minor Homebrew GCC upgrade caused major breakage. The "Darwin
compatibility" patch applied to GCC implemented the `availability`
compiler attribute in GCC. Apple SDK detected this and enabled using
them, but as it turns out GCC accepts compiler attributes with slightly
different rules than llvm/clang, and how the Apple SDK uses them,
breaking builds.
Affected Homebrew GCC versions are: 12.4.0, 13.3.0 and 14.1.0.
Possibly tracked here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108796
More info: https://github.com/llvm/llvm-project/issues/81767
Commit implementing the `availability` macro:
gcc-12: fd5530b7cb
gcc-13: cb7e4eca68
gcc-14: ff62a10886
That applied to Homebrew GCC (12.4.0):
b904223d98 (diff-89dd0b4176eca7fcc24b591943509bf8a8d6ea904d71e5dfcd6b78fed62fc574R44-R48)
Ref: #13700
More info: https://github.com/curl/curl/pull/14091#issuecomment-2222703468e91fcbac7d#14155 macos: undo `availability` macro enabled by Homebrew gcc
3. Proprietary Apple SDK macros
Apple SDK expects certain macros predefined by the compiler. Missing
them may causes odd issues. Mainline llvm is keeping up with Apple
clang, but it needs a fresh version, while the one installed on GitHub
runners is old (v15). I patched these in `lib/curl_setup.h`.
baa3270846#14134 build: fix llvm 16 or older + Xcode 15 or newer, and gcc
4. Apple SDK header bug
Without certain predefined macros, SDK headers can take a codepath where
it mis-defines its own `TARGET_OS_OSX` macro, which make it break its
own headers later. I patched it in `lib/curl_setup.h`.
ff784af461#14159 build: fix llvm 17 and older + macOS SDK 14.4 and newer
5. `TargetConditionals.h` requires `sys/types.h`
Fixed in curl. It caused feature-detection failurs with autotools, and
could break builds in certain configurations.
e1f6192939#14130 configure: fix `SystemConfiguration` detection
6. Differences between autotools and CMake compiler options
Fixed it by syncing compiler warning options.
59cadacfcc#14128 build: sync warning options between autotools, cmake & compilers
7. Differences between autotools and CMake dependency detection
Fixed it by improving detection of libidn2, with some more fixes
pending for the next feature window.
f43adc2c49#14137 cmake: detect `libidn2` also via `pkg-config`
Ref: #14136 cmake: detect `nghttp2` via `pkg-config`, enable by default
8. libidn2 detection bug with CMake
Fixed the root cause and also the trigger in the CI config.
764fbabf6e#14175 cmake: fix builds with detected libidn2 lib but undetected header
9. Suppressed compiler warnings inside Apple-specific curl code
Fixed these warnings, which allowed to stop silencing them.
b05dc7eb35#14122 sectransp: fix `HAVE_BUILTIN_AVAILABLE` checks to not emit warnings
5fa534b0da#14162 sectransp: fix clang compiler warnings, stop silencing them
10. CMake mis-detecting a CA bundle path on macOS
d2ef6255f4#14182 cmake: sync CA bundle/path detection with autotools
11. Failure to build tests with LibreSSL or wolfSSL with CMake
Fixed by dropping unnecessary includes, makign test builds dependent
on dependency headers.
3765d75ce4#14172 cmake: fix building `unit1600` due to missing `ssl/openssl.h`
12. curl tests with CMake
curl's CMake was missing bits for running the C preprocessor accurately.
It made tests 1119 and 1167 fail. I implemented the missing bits.
efc2c5184d#14124 tests: include current directory when running test Perl commands
c09db8b51b#14129 cmake: create `configurehelp.pm` like autotools does
67cc1e3400#14125 test1119: adapt for `.md` input
13. GCC missing `__builtin_available()` support
curl source code assumes this is available to enable certain codepaths.
It's also intermixed with monotonic timer support.
14. Monotonic timer support with GCC
Detected by GCC, while it probably shouldn't be. llvm/clang detects it
depending on target OS version. I've been playing with this, but so far
without a conclusion or fix.
15. Runtime/test failures with GCC
I couldn't find the reason for most of this. A bunch of RTSP tests fail
with GCC. SecureTransport + HTTP/2 is failing a bunch of tests. With
OpenSSL it fails two of those. SecureTransport builds also fail one DoH
test.
16. Runtime/test failure in llvm/clang
AppleIDN support received a fix with two more remaining.
fd0250869f#14179#14176 IDN: fix ß with AppleIDN
17. Other issues found and fixed while working on this:
2c15aa5765 GHA/macos: delete misplaced `CFLAGS`, drop redundant CMake option
80fb7c0bef#14126 configure: limit `SystemConfiguration` test to non-c-ares, IPv6 builds
cfd6f43d6c#14127 build: tidy up `__builtin_available` feature checks (Apple)
bae5553599#14174 runtests: show name and keywords for failed tests in summary
09cdf7e531#14178 cmake: delete unused `HAVE_LIBSSH2`, `HAVE_LIBSOCKET` macros
d3595c74fa#14186 configure: CA bundle/path detection fixes
58772b0e08#14187 runtests: set `SOURCE_DATE_EPOCH` to fix failing around midnight
18f1cd7a77#14183 tests: sync feature names with `curl -V`
4c22d97be7#14181 build: use `#error` instead of invalid syntax
Pending merge:
1e75edd372