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[readme] more examples

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@ -60,19 +60,6 @@ used, run:
$ bazel query @zig_sdk//... | sed -En '/.*_toolchain$/ s/.*:(.*)_toolchain$/\1/p' $ 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) ## Specifying non-default toolchains (and not registering at all)
You may explicitly request Bazel to use a specific toolchain, even though one 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 command-line argument. Otherwise Bazel will use the default one -- the host
toolchain. 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 # Known Issues In bazel-zig-cc
These are the things you may stumble into when using bazel-zig-cc. I am 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. unlikely to implement them any time soon, but patches implementing those will
See [Questions & Contributions](#questions-amp-contributions) on how to be accepted. See [Questions & Contributions](#questions-amp-contributions) on
contribute. 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.
## Zig cache ## Zig cache
@ -133,6 +121,18 @@ targets are in their own namespace.
Likewise, platforms are `@zig_sdk//:<platform>_platform`, and should be moved Likewise, platforms are `@zig_sdk//:<platform>_platform`, and should be moved
to `@zig_sdk//:platform:<platform>`. 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 # Known Issues In Upstream
This section lists issues that I've stumbled into when using `zig cc`, and is 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 # Testing
## linux cgo + glibc 2.28 ## build & run linux cgo + glibc
``` ```
$ bazel build --platforms @zig_sdk//:linux_amd64_platform //test/go:go $ bazel build --platforms @zig_sdk//:linux_amd64_platform //test/go:go
$ file bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/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 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 $ bazel-out/k8-opt-ST-d17813c235ce/bin/test/go/go_/go
hello, world 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 ## macos cgo
``` ```