Add exec_constraints attribute to POSIX toolchain

README.md

@@ -1493,7 +1493,7 @@ default is <code>None</code>
 ### nixpkgs_sh_posix_configure
 
 <pre>
-nixpkgs_sh_posix_configure(<a href="#nixpkgs_sh_posix_configure-name">name</a>, <a href="#nixpkgs_sh_posix_configure-packages">packages</a>, <a href="#nixpkgs_sh_posix_configure-kwargs">kwargs</a>)
+nixpkgs_sh_posix_configure(<a href="#nixpkgs_sh_posix_configure-name">name</a>, <a href="#nixpkgs_sh_posix_configure-packages">packages</a>, <a href="#nixpkgs_sh_posix_configure-exec_constraints">exec_constraints</a>, <a href="#nixpkgs_sh_posix_configure-kwargs">kwargs</a>)
 </pre>
 
 Create a POSIX toolchain from nixpkgs.
@@ -1539,6 +1539,20 @@ default is <code>["stdenv.initialPath"]</code>
 
 List of Nix attribute paths to draw Unix tools from.
 
+</p>
+</td>
+</tr>
+<tr id="nixpkgs_sh_posix_configure-exec_constraints">
+<td><code>exec_constraints</code></td>
+<td>
+
+optional.
+default is <code>None</code>
+
+<p>
+
+Constraints for the execution platform.
+
 </p>
 </td>
 </tr>

toolchains/posix/posix.bzl

@@ -109,6 +109,7 @@ create_posix_toolchain()
 def _nixpkgs_sh_posix_toolchain_impl(repository_ctx):
     exec_constraints, _ = ensure_constraints_pure(
         default_constraints = default_constraints(repository_ctx),
+        exec_constraints = repository_ctx.attr.exec_constraints,
     )
     repository_ctx.file("BUILD", executable = False, content = """
 toolchain(
@@ -129,12 +130,14 @@ _nixpkgs_sh_posix_toolchain = repository_rule(
     _nixpkgs_sh_posix_toolchain_impl,
     attrs = {
         "workspace": attr.string(),
+        "exec_constraints": attr.string_list(),
     },
 )
 
 def nixpkgs_sh_posix_configure(
         name = "nixpkgs_sh_posix_config",
         packages = ["stdenv.initialPath"],
+        exec_constraints = None,
         **kwargs):
     """Create a POSIX toolchain from nixpkgs.
 
@@ -148,6 +151,7 @@ def nixpkgs_sh_posix_configure(
     Args:
       name: Name prefix for the generated repositories.
       packages: List of Nix attribute paths to draw Unix tools from.
+      exec_constraints: Constraints for the execution platform.
       nix_file_deps: See nixpkgs_package.
       repositories: See nixpkgs_package.
       repository: See nixpkgs_package.
@@ -157,6 +161,7 @@ def nixpkgs_sh_posix_configure(
     nixpkgs_sh_posix_config(
         name = name,
         packages = packages,
+        exec_constraints = exec_constraints,
         **kwargs
     )