downgrade glibc to 2.19 and update README

README.md

@@ -1,39 +1,32 @@
-To run the example locally, first make sure `bazelisk` is on your PATH. Then
+# Bazel zig cc toolchain for Go
 
-Test that things work at all:
+This is a prototype zig-cc toolchain for cgo programs with:
+
+- glibc 2.19
+- musl.
+
+# Testing
+
+Building a cgo binary with glibc:
 
 ```
-$ bazelisk run //test:hello
+$ bazel build //test:gognu
 ...
-Hello World!
+$ ../bazel-bin/test/gognu_/gognu
+hello, world
+$ file ../bazel-bin/test/gognu_/gognu
+../bazel-bin/test/gognu_/gognu: 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
 ```
 
-Then test that you can run docker images:
+Build a cgo binary with musl:
+
 ```
-$ bazelisk run //test:hello_image
+$ bazel build --platforms @com_github_ziglang_zig//:platform_linux-x86_64-musl :gomusl
 ...
-Hello World!
-```
-
-Now we can check if C++ exceptions work locally:
-```
-$ bazelisk run //test:exception
-...
-will throw and expect to catch an error...
-caught: error
-done
-```
-
-And whether or not they work in a docker container:
-```
-$ bazelisk run //test:exception_image
-```
-
-If they *work*, then you'll see the same output as above. If not, you'll see:
-
-```
-will throw and expect to catch an error...
-libc++abi: terminating with uncaught exception of type char const*
+$ file ../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/gomusl_/gomusl
+../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/gomusl_/gomusl: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, Go BuildID=redacted, with debug_info, not stripped
+$ ../bazel-out/k8-fastbuild-ST-d17813c235ce/bin/test/gomusl_/gomusl
+hello, world
 ```
 
 If you want to try the above in a transient docker environment, you can do:
@@ -43,6 +36,6 @@ $ docker run --rm -it -v $(pwd):/workspace debian:buster-slim
 # apt update && apt install curl ca-certificates --no-install-recommends -y && curl -L https://github.com/bazelbuild/bazelisk/releases/download/v1.7.5/bazelisk-linux-amd64 > /usr/bin/bazel && chmod +x /usr/bin/bazel
 # cd /workspace
 # export CC=/usr/bin/false
-# bazel run --platforms=@com_github_ziglang_zig//:x86_64-linux-gnu.2.28 //test:hello
-# bazel run --platforms=@com_github_ziglang_zig//:x86_64-linux-gnu.2.28 //test:exception
-```
+# bazel run --platforms @com_github_ziglang_zig//:platform_linux-x86_64-musl :gomusl
+# bazel run --platforms @com_github_ziglang_zig//:platform_linux-x86_64-glibc :gomusl
+```