The active contributors and maintainers of Zig's linker code have
generally found the current linker test harness to be cumbersome. The
tests require a lot of maintenance, but do not provide a lot of
coverage, and when they fail it is painful to troubleshoot.
Furthermore, as part of working on #31691, I don't want to port over the
CheckObject step, because I don't like the code anyway.
The plan forward is to start enhancing `zig objdump` to assist in
linker development, as well as using it as the basis for snapshot
testing.
We absolutely need linker test coverage, but we need to try to improve
these things about the next attempt:
* less effort to create and maintain tests
* less CPU overhead - we should be able to add a lot of tests without
adding a lot of CI time.
* more helpful failures. A failed linker test should provide the next
steps a developer can take to understand why the test failed.
* a goal of porting over all of LLD's test suite, or at least the good
ones.
I'm not going to open an issue to track the lost linker test coverage,
because there was already so much lack of coverage for linker stuff.
However I will open issues to track this lost coverage:
* the deleted checks from test/standalone/glibc_compat/build.zig
* the deleted checks from test/standalone/compiler_rt_panic/build.zig
* the deleted checks from test/standalone/ios/build.zig
This change is seemingly insignificant but I actually agonized over this
for three days. Some other things I considered:
* (status quo in master branch) make Compile step creation functions
accept a Target.Query and delete the ResolvedTarget struct.
- downside: redundantly resolve target queries many times
* same as before but additionally add a hash map to cache target query
resolutions.
- downside: now there is a hash map that doesn't actually need to
exist, just to make the API more ergonomic.
* add is_native_os and is_native_abi fields to std.Target and use it
directly as the result of resolving a target query.
- downside: they really don't belong there. They would be available
as comptime booleans via `@import("builtin")` but they should not
be exposed that way.
With this change the downsides are:
* the option name of addExecutable and friends is `target` instead of
`resolved_target` matching the type name.
- upside: this does not break compatibility with existing build
scripts
* you likely end up seeing `target.result.cpu.arch` rather than
`target.cpu.arch`.
- upside: this is an improvement over `target.target.cpu.arch` which
it was before this commit.
- downside: `b.host.target` is now `b.host.result`.
Introduce the concept of "target query" and "resolved target". A target
query is what the user specifies, with some things left to default. A
resolved target has the default things discovered and populated.
In the future, std.zig.CrossTarget will be rename to std.Target.Query.
Introduces `std.Build.resolveTargetQuery` to get from one to the other.
The concept of `main_mod_path` is gone, no longer supported. You have to
put the root source file at the module root now.
* remove deprecated API
* update build.zig for the breaking API changes in this branch
* move std.Build.Step.Compile.BuildId to std.zig.BuildId
* add more options to std.Build.ExecutableOptions, std.Build.ObjectOptions,
std.Build.SharedLibraryOptions, std.Build.StaticLibraryOptions, and
std.Build.TestOptions.
* remove `std.Build.constructCMacro`. There is no use for this API.
* deprecate `std.Build.Step.Compile.defineCMacro`. Instead,
`std.Build.Module.addCMacro` is provided.
- remove `std.Build.Step.Compile.defineCMacroRaw`.
* deprecate `std.Build.Step.Compile.linkFrameworkNeeded`
- use `std.Build.Module.linkFramework`
* deprecate `std.Build.Step.Compile.linkFrameworkWeak`
- use `std.Build.Module.linkFramework`
* move more logic into `std.Build.Module`
* allow `target` and `optimize` to be `null` when creating a Module.
Along with other fields, those unspecified options will be inherited
from parent `Module` when inserted into an import table.
* the `target` field of `addExecutable` is now required. pass `b.host`
to get the host target.
* introduce LazyPath.cwd_relative variant and use it for --zig-lib-dir. closes#12685
* move overrideZigLibDir and setMainPkgPath to options fields set once
and then never mutated.
* avoid introducing Build/util.zig
* use doc comments for deprecation notices so that they show up in
generated documentation.
* introduce InstallArtifact.Options, accept it as a parameter to
addInstallArtifact, and move override_dest_dir into it. Instead of
configuring the installation via Compile step, configure the
installation via the InstallArtifact step. In retrospect this is
obvious.
* remove calls to pushInstalledFile in InstallArtifact. See #14943
* rewrite InstallArtifact to not incorrectly observe whether a Compile
step has any generated outputs. InstallArtifact is meant to trigger
output generation.
* fix child process evaluation code handling of `-fno-emit-bin`.
* don't store out_h_filename, out_ll_filename, etc., pointlessly. these
are all just simple extensions appended to the root name.
* make emit_directory optional. It's possible to have nothing outputted,
for example, if you're just type-checking.
* avoid passing -femit-foo/-fno-emit-foo when it is the default
* rename ConfigHeader.getTemplate to getOutput
* deprecate addOptionArtifact
* update the random number seed of Options step caching.
* avoid using `inline for` pointlessly
* avoid using `override_Dest_dir` pointlessly
* avoid emitting an executable pointlessly in test cases
Removes forceBuild and forceEmit. Let's consider these additions separately.
Nearly all of the usage sites were suspicious.
Andrew Kelley