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
 ```

test/BUILD

@@ -1,15 +1,26 @@
-cc_binary(
-    name = "hello",
-    srcs = ["hello.cpp"],
+load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
+
+go_library(
+    name = "go_lib",
+    srcs = ["hello.go"],
+    cgo = True,
+    importpath = "github.com/motiejus/bazel-zig-cc/test",
+    visibility = ["//visibility:private"],
+)
+
+go_binary(
+    name = "gognu",
+    embed = [":go_lib"],
+    visibility = ["//visibility:public"],
+)
+
+go_binary(
+    name = "gomusl",
+    embed = [":go_lib"],
+    static = "on",
     target_compatible_with = select({
         "@platforms//os:linux": ["@com_github_ziglang_zig//:musl"],
         "//conditions:default": [],
     }),
+    visibility = ["//visibility:public"],
 )
-
-cc_binary(
-    name = "exception",
-    srcs = ["exception.cpp"],
-)
-
-# go build -ldflags "-linkmode external -extldflags -static" hello.go

test/c/BUILD

@@ -1,13 +0,0 @@
-cc_binary(
-    name = "hello",
-    srcs = ["hello.cpp"],
-    target_compatible_with = select({
-        "@platforms//os:linux": ["@com_github_ziglang_zig//:musl"],
-        "//conditions:default": [],
-    }),
-)
-
-cc_binary(
-    name = "exception",
-    srcs = ["exception.cpp"],
-)

test/c/exception.cpp

@@ -1,12 +0,0 @@
-#include <iostream>
-
-int main() {
-  std::cerr << "will throw and expect to catch an error..." << std::endl;
-
-  try {
-    throw "error";
-  } catch (const char* msg) {
-    std::cerr << "caught: " << msg << std::endl;
-  }
-  std::cerr << "done" << std::endl;
-}

test/c/hello.cpp

@@ -1,5 +0,0 @@
-#include <iostream>
-
-int main() {
-    std::cout << "Hello World!" << std::endl;
-}

test/go/BUILD

@@ -1,21 +0,0 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
-
-# go build -ldflags "-linkmode external -extldflags -static" hello.go
-go_library(
-    name = "go_lib",
-    srcs = ["hello.go"],
-    cgo = True,
-    importpath = "github.com/motiejus/bazel-zig-cc/test/go",
-    visibility = ["//visibility:private"],
-    target_compatible_with = select({
-        "@platforms//os:linux": ["@com_github_ziglang_zig//:musl"],
-        "//conditions:default": [],
-    }),
-)
-
-go_binary(
-    name = "go",
-    embed = [":go_lib"],
-    visibility = ["//visibility:public"],
-    static = "on",
-)

zig-toolchains/defs.bzl

@@ -39,7 +39,7 @@ TARGET_CONFIGS = [
     # the platform is explicitly set to:
     # --platforms=@com_github_ziglang_zig//:x86_64-linux-musl
     struct(
-        target="x86_64-linux-gnu.2.28",
+        target="x86_64-linux-gnu.2.19",
         includes=[
             "libunwind/include",
             "libc/include/generic-glibc",
@@ -53,7 +53,7 @@ TARGET_CONFIGS = [
         constraint_values=[
             "@platforms//os:linux",
             "@platforms//cpu:x86_64",
-            ":glibc_2_28",
+            ":glibc_2_19",
         ],
         tool_paths={"ld": "ld.lld"},
     ),
@@ -126,7 +126,7 @@ zig_build_macro(absolute_path={absolute_path}, zig_include_root={zig_include_roo
 constraint_setting(name = "libc")
 
 constraint_value(
-    name = "glibc_2_28",
+    name = "glibc_2_19",
     constraint_setting = ":libc",
 )
 
@@ -150,7 +150,7 @@ platform(
     constraint_values = [
         "@platforms//os:linux",
         "@platforms//cpu:x86_64",
-        ":glibc_2_28",
+        ":glibc_2_19",
     ],
 )