This makes it so that when there is a tree of std.Build objects, only
one zig-cache is used (the top-level application) instead of polluting
package directories with zig-cache folders.
* Use std.Build.Cache.Directory instead of a string for storing the
cache roots and build roots.
* Set up a std.Build.Cache in build_runner.zig and use it in
std.Build.RunStep for avoiding redundant work.
Deprecate CompileStep.run. The problem with this function is that it
does the RunStep with the same build.zig context as the CompileStep, but
this is not desirable when running an executable that is provided by a
dependency package. Instead, users should use `b.addRunArtifact`.
This has the additional benefit of conforming to the existing naming
conventions.
Additionally, support enum literals in config header options values.
Breaking API change to std.Build.addConfigHeader. It now uses an options
struct.
Introduce std.Build.CompileStep.installConfigHeader which also accepts
an options struct. This is used to add a generated config file into the
set of installed header files for a particular compilation artifact.
std.Build.ConfigHeaderStep now additionally supports a "blank" style
where a header is generated from scratch. It no longer exposes
`output_dir`. Instead it exposes a FileSource via `output_file`.
It now additionally accepts an `include_path` option which affects the
include path of CompileStep when using the `#include` directive, as well
as affecting the default installation subdirectory for header
installation purposes.
The hash used for the directory to store the generated config file now
includes the contents of the generated file. This fixes possible race
conditions when generating multiple header files simultaneously.
The values hash table is now an array hash map, to preserve order for
the "blank" use case.
I also took the opportunity to remove output_dir from TranslateCStep and
WriteFileStep. This is technically a breaking change, but it was always
naughty to access these fields.
Add ability to generate a c header file from scratch, and then both
compile with it and install it if needed.
Example:
```zig
const avconfig_h = b.addConfigHeader(.{ .path = "libavutil/avconfig.h" }, .generated, .{
.AV_HAVE_BIGENDIAN = 0, // TODO: detect based on target
.AV_HAVE_FAST_UNALIGNED = 1, // TODO: detect based on target
});
lib.addConfigHeader(avconfig_h);
lib.installConfigHeader(avconfig_h);
```
New API introduced: std.Build.addModule
This function exposes a zig module with the given name, which can be
used by packages that depend on this one via std.Build.Dependency.module.
std.Build.Pkg and related functionality is deleted. Every use case has a
straightforward upgrade path using the new Module struct.
std.Build.OptionsStep.getPackage is replaced by
std.Build.OptionsStep.createModule.
std.Build.CompileStep.addPackagePath is replaced by
std.Build.CompileStep.addAnonymousModule.
This partially addresses #14307 by renaming some of the instances of
"package" to "module".
Closes#14278
Usage of `catch unreachable` in build scripts is completely harmless
because build scripts are always run in Debug mode, however, it sets a
poor example for beginners to learn from.
