Fixed Windows installation

conda.bzl

@@ -68,7 +68,10 @@ def _install_conda(rctx, installer):
 
     # execute installer with flags adjusted to OS
     if os == "Windows":
-        result = execute_waitable_windows(rctx, args, quiet=rctx.attr.quiet)
+        # TODO: fix always returning 0
+        # it seems that either miniconda installer returns 0 even on failure or the wrapper does something wrong
+        # also stdout and stderr are always empty
+        result = execute_waitable_windows(rctx, args, quiet=rctx.attr.quiet, environment={"CONDA_DLL_SEARCH_MODIFICATION_ENABLE": ""})
     else:
         result = rctx.execute(args, quiet=rctx.attr.quiet)
 

utils.bzl

@@ -62,10 +62,22 @@ def get_arch(rctx):
     return get_arch_linux(rctx)
 
 
-def execute_waitable_windows(rctx, args, tmp_script="tmp.bat", **kwargs):
+TMP_SCRIPT_TEMPLATE = """
+@echo off
+if "%OS%"=="Windows_NT" setlocal
+{envs}
+call {args}
+set "EXITCODE=%ERRORLEVEL%"
+if "%OS%"=="Windows_NT" ( endlocal & exit /b "%EXITCODE%" )
+exit /b "%EXITCODE%""
+"""
+
+
+def execute_waitable_windows(rctx, args, environment={}, tmp_script="tmp.bat", **kwargs):
     rctx.file(
         tmp_script,
-        content = """start /wait "" {}""".format(" ".join([str(a) for a in args]))
+        content = TMP_SCRIPT_TEMPLATE.format(envs='\n'.join(["set \"{}={}\"".format(k, v) for k, v in environment.items()]),
+                                             args=" ".join([str(a) for a in args]))
     )
     result = rctx.execute([rctx.path(tmp_script)], **kwargs)
     rctx.delete(tmp_script)