[test] lit.cfg: TARGET_ENV_PREFIX ⟹ config.target_env_prefix

Also, integrate its configuration into the preexisting target if ladders, where it belongs.

Author: lorentey

test/lit.cfg

@@ -940,6 +940,7 @@ config.target_cxx_lib = '-lc++'
 config.target_msvc_runtime_opt = ''
 config.target_static_library_prefix = 'lib'
 config.target_static_library_suffix = '.a'
+config.target_env_prefix = ''
 
 if run_vendor == 'apple':
     target_specific_module_triple = '{}-apple-{}'.format(
@@ -1080,6 +1081,8 @@ if run_vendor == 'apple':
            xcrun_sdk_name = "watchos"
            target_future_version = "9.99.0"
 
+       config.target_env_prefix = 'IOS_CHILD_'
+
        config.target_cc_options = (
            "-target %s %s" %
            (config.variant_triple, clang_mcp_opt))
@@ -1122,6 +1125,8 @@ if run_vendor == 'apple':
 
         target_specific_module_triple += "-simulator"
 
+        config.target_env_prefix = 'SIMCTL_CHILD_'
+
         config.target_cc_options = (
             "-target %s %s" %
             (config.variant_triple, clang_mcp_opt))
@@ -1330,6 +1335,7 @@ elif run_os in ['windows-msvc']:
     config.target_msvc_runtime_opt = '-%s -D_MT' % config.swift_stdlib_msvc_runtime
     if 'D' in config.swift_stdlib_msvc_runtime:
         config.target_msvc_runtime_opt += ' -D_DLL'
+    config.target_env_prefix = ''
 
     config.target_build_swift =                                                  \
             ('%r -target %s %s %s %s %s -libc %s' %                              \
@@ -1439,6 +1445,7 @@ elif (run_os in ['linux-gnu', 'linux-gnueabihf', 'freebsd', 'openbsd', 'windows-
       config.target_shared_library_suffix = ".so"
       config.target_sdk_name = "android"
       config.target_cc_options = "-fPIE"
+      config.target_env_prefix = 'ANDROID_CHILD_'
     else:
       lit_config.note("Testing Linux " + config.variant_triple)
       config.target_object_format = "elf"
@@ -1572,6 +1579,7 @@ elif run_os == 'linux-androideabi' or run_os == 'linux-android':
     config.target_runtime = "native"
     config.target_swift_autolink_extract = inferSwiftBinary("swift-autolink-extract")
     config.target_sdk_name = "android"
+    config.target_env_prefix = 'ANDROID_CHILD_'
     config.resource_dir_opt = ("-resource-dir %s" % test_resource_dir)
     # Since NDK r19, the headers and libraries are available in a unified
     # sysroot at $NDK_PATH/toolchains/llvm/prebuilt/$prebuilt_directory/sysroot,
@@ -1775,19 +1783,6 @@ config.substitutions.append(('%string_processing_module', string_processing_modu
 config.substitutions.append(('%/string_processing_module',
                              '/'.join(os.path.normpath(string_processing_module).split(os.sep))))
 
-# Different OS's require different prefixes for the environment variables to be
-# propagated to the calling contexts.
-# In order to make tests OS-agnostic, names of environment variables should be
-# prefixed with `%env-`, which is then expanded to the appropriate prefix.
-SIMULATOR_ENV_PREFIX = 'SIMCTL_CHILD_'
-ENV_VAR_PREFIXES = {
-    'iphonesimulator': SIMULATOR_ENV_PREFIX,
-    'watchsimulator': SIMULATOR_ENV_PREFIX,
-    'appletvsimulator': SIMULATOR_ENV_PREFIX,
-    'android': 'ANDROID_CHILD_'
-}
-TARGET_ENV_PREFIX = ENV_VAR_PREFIXES.get(config.target_sdk_name, "") if not kIsAndroid else ""
-
 back_deployment_runtime = lit_config.params.get('back_deployment_runtime', None)
 if back_deployment_runtime is not None:
     config.available_features.add('back_deployment_runtime')
@@ -1861,6 +1856,7 @@ if 'remote_run_host' in lit_config.params:
                      os.path.dirname(local_swift_reflection_test),
                      'bin/')
 
+    config.target_env_prefix = 'REMOTE_RUN_CHILD_'
     config.target_run = (
         "/usr/bin/env "
         "REMOTE_RUN_CHILD_DYLD_LIBRARY_PATH='{0}' " # Apple option
@@ -1874,10 +1870,14 @@ if 'remote_run_host' in lit_config.params:
                                               remote_run_host))
     config.target_swift_reflection_test = os.path.join(
         remote_tmp_dir, 'bin', swift_reflection_test_name)
-    TARGET_ENV_PREFIX = 'REMOTE_RUN_CHILD_'
     config.available_features.add('remote_run')
 
-config.substitutions.append(('%env-', TARGET_ENV_PREFIX))
+# Different OS's require different prefixes for the environment variables to be
+# propagated to the calling contexts.
+# In order to make tests OS-agnostic, names of environment variables should be
+# prefixed with `%env-`, which is then expanded to the appropriate prefix.
+config.substitutions.append(('%env-', config.target_env_prefix))
+
 config.substitutions.append(("%target-sdk-name", config.target_sdk_name))
 
 simulator_sdks = [
@@ -2410,7 +2410,7 @@ config.substitutions.append(('%import-static-libdispatch', getattr(config, 'impo
 config.environment['SWIFT_DEBUG_ENABLE_COW_CHECKS'] = 'false'
 
 # Add this to the command which runs an executable to enable COW checks in the swift runtime.
-config.substitutions.append(('%enable-cow-checking', TARGET_ENV_PREFIX + 'SWIFT_DEBUG_ENABLE_COW_CHECKS=true;'))
+config.substitutions.append(('%enable-cow-checking', config.target_env_prefix + 'SWIFT_DEBUG_ENABLE_COW_CHECKS=true;'))
 
 # We add an expansion to ensure that migrator tests can search for the api diff
 # data dir from the host compiler toolchain instead of the resource dir of the
@@ -2445,10 +2445,10 @@ if config.lldb_build_root != "":
 # Disable randomized hash seeding by default. Tests need to manually opt in to
 # random seeds by unsetting the SWIFT_DETERMINISTIC_HASHING environment
 # variable.
-config.environment[TARGET_ENV_PREFIX + 'SWIFT_DETERMINISTIC_HASHING'] = '1'
+config.environment[config.target_env_prefix + 'SWIFT_DETERMINISTIC_HASHING'] = '1'
 
 # Enable malloc scribble during tests by default.
-config.environment[TARGET_ENV_PREFIX + 'SWIFT_DEBUG_ENABLE_MALLOC_SCRIBBLE'] = 'YES'
+config.environment[config.target_env_prefix + 'SWIFT_DEBUG_ENABLE_MALLOC_SCRIBBLE'] = 'YES'
 
 # Run lsb_release on the target to be tested and return the results.
 def linux_get_lsb_release():