Implement binary_toolchain

lib/binary_toolchain.bzl

@@ -0,0 +1,68 @@
+BinaryInfo = provider(
+    doc = "Provide info for binary",
+    fields = {
+        "bin": "Target for the binary",
+    },
+)
+
+def _toolchain_impl(ctx):
+    binary_info = BinaryInfo(
+        bin = ctx.attr.bin,
+    )
+
+    toolchain_info = platform_common.ToolchainInfo(
+        binary_info = binary_info,
+    )
+
+    return [toolchain_info]
+
+binary_toolchain = rule(
+    implementation = _toolchain_impl,
+    attrs = {
+        "bin": attr.label(
+            mandatory = True,
+            executable = True,
+            cfg = "exec",
+        ),
+    },
+)
+
+binary_runtime_toolchain = rule(
+    implementation = _toolchain_impl,
+    attrs = {
+        "bin": attr.label(
+            mandatory = True,
+            allow_single_file = True,
+            executable = True,
+            cfg = "target",
+        ),
+    },
+)
+
+def _resolved_binary_rule_impl(ctx, toolchain_type, template_variable):
+    bin = ctx.toolchains[toolchain_type].binary_info.bin[DefaultInfo]
+
+    out = ctx.actions.declare_file(ctx.attr.name + ".exe")
+    ctx.actions.symlink(
+        target_file = bin.files_to_run.executable,
+        output = out,
+        is_executable = True,
+    )
+
+    return [
+        DefaultInfo(
+            executable = out,
+            files = bin.files,
+            runfiles = bin.default_runfiles,
+        ),
+        platform_common.TemplateVariableInfo({
+            template_variable: out.path,
+        } if template_variable != None else {}),
+    ]
+
+def resolved_binary_rule(*, toolchain_type, template_variable = None):
+    return rule(
+        implementation = lambda ctx: _resolved_binary_rule_impl(ctx, toolchain_type, template_variable),
+        executable = True,
+        toolchains = [toolchain_type],
+    )