As reported by jacobly, the Apple system linker matches sections to
segments by name and not by flags causing Zig's executable section
ending up in a segment with incorrect permission flags.
Pass the required lazy dependencies from the build runner to the parent
process via a tmp file instead of stdout. I'll reproduce this comment to
explain it:
The `zig build` parent process needs a way to obtain results from the
configuration phase of the child process. In the future, the make phase
will be executed in a separate process than the configure phase, and we
can then use stdout from the configuration phase for this purpose.
However, currently, both phases are in the same process, and Run Step
provides API for making the runned subprocesses inherit stdout and stderr
which means these streams are not available for passing metadata back
to the parent.
Until make and configure phases are separated into different processes,
the strategy is to choose a temporary file name ahead of time, and then
read this file in the parent to obtain the results, in the case the child
exits with code 3.
This commit also extracts some common logic from the loop that rebuilds
the build runner so that it does not run again when the build runner is
rebuilt.
Build manifest files support `lazy: true` for dependency sections.
This causes the auto-generated dependencies.zig to have 2 more
possibilities:
1. It communicates whether a dependency is lazy or not.
2. The dependency might be acknowledged, but missing due to being lazy
and not fetched.
Lazy dependencies are not fetched by default, but if they are already
fetched then they are provided to the build script.
The build runner reports the set of missing lazy dependenices that are
required to the parent process via stdout and indicates the situation
with exit code 3.
std.Build now has a `lazyDependency` function. I'll let the doc comments
speak for themselves:
When this function is called, it means that the current build does, in
fact, require this dependency. If the dependency is already fetched, it
proceeds in the same manner as `dependency`. However if the dependency
was not fetched, then when the build script is finished running, the
build will not proceed to the make phase. Instead, the parent process
will additionally fetch all the lazy dependencies that were actually
required by running the build script, rebuild the build script, and then
run it again.
In other words, if this function returns `null` it means that the only
purpose of completing the configure phase is to find out all the other
lazy dependencies that are also required.
It is allowed to use this function for non-lazy dependencies, in which
case it will never return `null`. This allows toggling laziness via
build.zig.zon without changing build.zig logic.
The CLI for `zig build` detects this situation, but the logic for then
redoing the build process with these extra dependencies fetched is not
yet implemented.
This allows a `zig build` command to specify intention to create a
release build, regardless of what per-project options exist. It also
allows the command to specify a "preferred optimization mode", which is
chosen if the project itself does not choose one (in other words, the
project gets first choice). If neither the build command nor the project
specify a preferred release mode, an error occurs.
Before it was named "library" inconsistently.
Now the CLI args are -fsys=[name] and -fno-sys=[name] and it is a more
general-purpose "system integration" which could be a library name or
perhaps a project name such as "ffmpeg" or a binary such as "nasm".
This also makes a long-overdue change of extracting common state from
Build into a shared Graph object.
Getting the semantics right for these flags turned out to be quite
tricky. In the end it works like this:
* The override only happens when the target is fully native, with no
additional query parameters, such as versions or CPU features added.
* The override affects the resolved Target but leaves the original Query
unmodified.
* The "is native?" detection logic operates on the original, unmodified
query. This makes it possible to provide invalid host target
information, causing confusing errors to occur. Don't do that.
There are some minor breaking changes to std.Build API such as the fact
that `b.zig_exe` is now moved to `b.graph.zig_exe`, as well as a handful
of other similar flags.
These are advanced options that make it possible to simultaneously
target the "host" computer, while overriding assumptions about the host
computer such as what CPU features are available, or what OS version
range to target.
This is useful only for the case of integrating with system package
manager builds which want to pretend the host is also the target.
