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hermetic_cc_toolchain
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[readme] more examples

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Motiejus Jakštys 2022-02-05 11:16:16 +02:00
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@ -60,19 +60,6 @@ used, run:
$ bazel query @zig_sdk//... | sed -En '/.*_toolchain$/ s/.*:(.*)_toolchain$/\1/p'
```
## UBSAN and "SIGILL: Illegal Instruction"
`zig cc` differs from "mainstream" compilers by [enabling UBSAN by
default][ubsan1]. Which means your program may compile successfully and crash
with:
```
SIGILL: illegal instruction
```
This is by design: it encourages program authors to fix the undefined behavior.
There are [many ways][ubsan2] to find the undefined behavior.
## Specifying non-default toolchains (and not registering at all)
You may explicitly request Bazel to use a specific toolchain, even though one
@ -94,24 +81,25 @@ In that case, you will need to specify the `--extra_toolchains <toolchain>`
command-line argument. Otherwise Bazel will use the default one -- the host
toolchain.
## UBSAN and "SIGILL: Illegal Instruction"
`zig cc` differs from "mainstream" compilers by [enabling UBSAN by
default][ubsan1]. Which means your program may compile successfully and crash
with:
```
SIGILL: illegal instruction
```
This is by design: it encourages program authors to fix the undefined behavior.
There are [many ways][ubsan2] to find the undefined behavior.
# Known Issues In bazel-zig-cc
These are the things you may stumble into when using bazel-zig-cc. I am
unlikely to implement them, but patches implementing those will be accepted.
See [Questions & Contributions](#questions-amp-contributions) on how to
contribute.
## OSX: sysroot
For non-trivial programs (and for all darwin/arm64 cgo programs) MacOS SDK may
be necessary. Read [Jakub's comment][sysroot] about it. Support for OSX sysroot
is currently not implemented.
## OSX: different OS targets (Catalina -- Monterey)
[Zig 0.9.0](https://ziglang.org/download/0.9.0/release-notes.html#macOS) may
target macos.10 (Catalina), macos.11 (Big Sur) or macos.12 (Monterey). It
currently targets the lowest version, without ability to change it.
unlikely to implement them any time soon, but patches implementing those will
be accepted. See [Questions & Contributions](#questions-amp-contributions) on
how to contribute.
## Zig cache
@ -133,6 +121,18 @@ targets are in their own namespace.
Likewise, platforms are `@zig_sdk//:<platform>_platform`, and should be moved
to `@zig_sdk//:platform:<platform>`.
## OSX: sysroot
For non-trivial programs (and for all darwin/arm64 cgo programs) MacOS SDK may
be necessary. Read [Jakub's comment][sysroot] about it. Support for OSX sysroot
is currently not implemented.
## OSX: different OS targets (Catalina -- Monterey)
[Zig 0.9.0](https://ziglang.org/download/0.9.0/release-notes.html#macOS) may
target macos.10 (Catalina), macos.11 (Big Sur) or macos.12 (Monterey). It
currently targets the lowest version, without ability to change it.
# Known Issues In Upstream
This section lists issues that I've stumbled into when using `zig cc`, and is
@ -165,27 +165,28 @@ may apply to aarch64, but the author didn't find a need to test it (yet).
# Testing
## linux cgo + glibc 2.28
## build & run linux cgo + glibc
```
$ bazel build --platforms @zig_sdk//:linux_amd64_platform //test/go:go
$ file bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.0.0, Go BuildID=redacted, with debug_info, not stripped
```
## linux cgo + musl
```
$ bazel build \
--platforms @zig_sdk//:linux_amd64_platform \
--extra_toolchains @zig_sdk//:linux_amd64_musl_toolchain //test/go:go
...
$ file bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, Go BuildID=redacted, stripped
$ bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
hello, world
```
## test linux cgo + musl on arm64 (under qemu-aarch64)
```
$ bazel test \
--run_under=qemu-aarch64 \
--platforms @zig_sdk//:linux_arm64_platform \
--extra_toolchains @zig_sdk//:linux_arm64_musl_toolchain //test/...
...
INFO: Build completed successfully, 10 total actions
//test/go:go_test PASSED in 0.2s
```
## macos cgo
```