From 8e8935bb30bc0d10e70c5e81ce8d7adf7f65dd4a Mon Sep 17 00:00:00 2001
From: Henry Schreiner <henryschreineriii@gmail.com>
Date: Thu, 21 Jan 2021 12:55:42 -0500
Subject: [PATCH] feat: auto32/auto64

---
 cibuildwheel/__main__.py |  2 +-
 cibuildwheel/util.py     | 26 +++++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/cibuildwheel/__main__.py b/cibuildwheel/__main__.py
index f5a7ace99..6078aa2b2 100644
--- a/cibuildwheel/__main__.py
+++ b/cibuildwheel/__main__.py
@@ -77,7 +77,7 @@ def main() -> None:
                             on this machine. Set this option to build an architecture
                             via emulation, for example, using binfmt_misc and QEMU.
                             Default: auto.
-                            Choices: auto, native, all, {}
+                            Choices: auto, auto64, auto32, native, all, {}
                         '''.format(", ".join(a.name for a in Architecture)))
     parser.add_argument('--output-dir',
                         default=os.environ.get('CIBW_OUTPUT_DIR', 'wheelhouse'),
diff --git a/cibuildwheel/util.py b/cibuildwheel/util.py
index 33435c16e..edbe36d43 100644
--- a/cibuildwheel/util.py
+++ b/cibuildwheel/util.py
@@ -18,7 +18,7 @@
 import toml
 
 from .environment import ParsedEnvironment
-from .typing import PathOrStr, PlatformName, assert_never
+from .typing import Literal, PathOrStr, PlatformName, assert_never
 
 if sys.version_info < (3, 9):
     from importlib_resources import files
@@ -192,6 +192,10 @@ def parse_config(config: str, platform: PlatformName) -> 'Set[Architecture]':
                 result.add(Architecture(platform_module.machine()))
             elif arch_str == 'all':
                 result |= Architecture.all_archs(platform=platform)
+            elif arch_str == "auto64":
+                result |= Architecture.bitiness_archs(platform=platform, bitiness="64")
+            elif arch_str == "auto32":
+                result |= Architecture.bitiness_archs(platform=platform, bitiness="32")
             else:
                 result.add(Architecture(arch_str))
         return result
@@ -218,6 +222,26 @@ def all_archs(platform: PlatformName) -> 'Set[Architecture]':
         else:
             assert_never(platform)
 
+    @staticmethod
+    def bitiness_archs(platform: PlatformName, bitiness: Literal["64", "32"]) -> 'Set[Architecture]':
+        native_architecture = Architecture(platform_module.machine())
+
+        if native_architecture in {Architecture.x86_64, Architecture.aarch64, Architecture.ppc64le, Architecture.s390x, Architecture.AMD64}:
+            if bitiness == "64":
+                return {native_architecture}
+            else:
+                if native_architecture == Architecture.x86_64 and platform != "macos":
+                    return {Architecture.i686}
+                elif native_architecture == Architecture.AMD64:
+                    return {Architecture.x86}
+                else:
+                    return set()
+        elif native_architecture in {Architecture.i686, Architecture.x86}:
+            return {native_architecture} if bitiness == "32" else set()
+        else:
+            # assert_never should work here
+            raise RuntimeError("Cannot be reached")
+
 
 class BuildOptions(NamedTuple):
     package_dir: Path