[utils] Introduce swift_build_support.diagnostics.

 - This uses more Clang/Swift-style diagnostics, and adds a convenient wrapper
   `fatal()` which happens to match what almost all clients of the previous
   `print_with_argv0` wanted to do (i.e., fail with a fatal error).

 - As part of this, I also tried to make the diagnostics more consistent and use
   "diagnostic style" casing/punctuation.

 - Part of SR-237.

Author: ddunbar

Diff for: utils/SwiftBuildSupport.py

@@ -25,6 +25,7 @@
 sys.path.append(os.path.join(os.path.dirname(__file__), 'swift_build_support'))
 
 # E402 means module level import not at top of file
+from swift_build_support import diagnostics  # noqa (E402)
 from swift_build_support import shell  # noqa (E402)
 
 
@@ -69,11 +70,6 @@ def _get_default_source_root():
     "SWIFT_BUILD_ROOT", os.path.join(SWIFT_SOURCE_ROOT, "build"))
 
 
-def print_with_argv0(message):
-    print(sys.argv[0] + ": " + message)
-    sys.stdout.flush()
-
-
 def check_call(args, print_command=False, verbose=False, disable_sleep=False):
     if disable_sleep:
         if platform.system() == 'Darwin':
@@ -87,17 +83,13 @@ def check_call(args, print_command=False, verbose=False, disable_sleep=False):
     try:
         return subprocess.check_call(args)
     except subprocess.CalledProcessError as e:
-        print_with_argv0(
+        diagnostics.fatal(
             "command terminated with a non-zero exit status " +
             str(e.returncode) + ", aborting")
-        sys.stdout.flush()
-        sys.exit(1)
     except OSError as e:
-        print_with_argv0(
+        diagnostics.fatal(
             "could not execute '" + shell.quote_command(args) +
             "': " + e.strerror)
-        sys.stdout.flush()
-        sys.exit(1)
 
 
 def check_output(args, print_command=False, verbose=False):
@@ -107,25 +99,20 @@ def check_output(args, print_command=False, verbose=False):
     try:
         return subprocess.check_output(args)
     except subprocess.CalledProcessError as e:
-        print_with_argv0(
+        diagnostics.fatal(
             "command terminated with a non-zero exit status " +
             str(e.returncode) + ", aborting")
-        sys.stdout.flush()
-        sys.exit(1)
     except OSError as e:
-        print_with_argv0(
+        diagnostics.fatal(
             "could not execute '" + shell.quote_command(args) +
             "': " + e.strerror)
-        sys.stdout.flush()
-        sys.exit(1)
 
 
 def _load_preset_files_impl(preset_file_names, substitutions={}):
     config = ConfigParser.SafeConfigParser(substitutions, allow_no_value=True)
     if config.read(preset_file_names) == []:
-        print_with_argv0(
+        diagnostics.fatal(
             "preset file not found (tried " + str(preset_file_names) + ")")
-        sys.exit(1)
     return config
 
 
@@ -190,12 +177,10 @@ def get_preset_options(substitutions, preset_file_names, preset_name):
     (build_script_opts, build_script_impl_opts, missing_opts) = \
         _get_preset_options_impl(config, substitutions, preset_name)
     if not build_script_opts and not build_script_impl_opts:
-        print_with_argv0("preset '" + preset_name + "' not found")
-        sys.exit(1)
+        diagnostics.fatal("preset '" + preset_name + "' not found")
     if missing_opts:
-        print_with_argv0("missing option(s) for preset '" + preset_name +
-                         "': " + ", ".join(missing_opts))
-        sys.exit(1)
+        diagnostics.fatal("missing option(s) for preset '" + preset_name +
+                          "': " + ", ".join(missing_opts))
 
     # Migrate 'swift-sdks' parameter to 'stdlib-deployment-targets'
     for opt in build_script_impl_opts:

Diff for: utils/build-script

@@ -31,13 +31,13 @@ from SwiftBuildSupport import (
     check_call,
     get_all_preset_names,
     get_preset_options,
-    print_with_argv0,
 )  # noqa (E402 module level import not at top of file)
 
 sys.path.append(os.path.join(os.path.dirname(__file__), 'swift_build_support'))
 
 # E402 means module level import not at top of file
 from swift_build_support import arguments  # noqa (E402)
+from swift_build_support import diagnostics  # noqa (E402)
 from swift_build_support.toolchain import host_toolchain  # noqa (E402)
 import swift_build_support.debug      # noqa (E402)
 from swift_build_support import migration  # noqa (E402)
@@ -102,8 +102,7 @@ def main_preset():
         return 0
 
     if not args.preset:
-        print_with_argv0("Missing --preset option")
-        return 1
+        diagnostics.fatal("missing --preset option")
 
     args.preset_substitutions = {}
 
@@ -121,7 +120,7 @@ def main_preset():
     if args.distcc:
         build_script_args += ["--distcc"]
 
-    print_with_argv0(
+    diagnostics.note(
         "using preset '" + args.preset + "', which expands to \n\n" +
         shell.quote_command(build_script_args) + "\n")
 
@@ -995,27 +994,22 @@ details of the setups of other systems or automated environments.""")
         toolchain.cmake = args.cmake
 
     if toolchain.cc is None or toolchain.cxx is None:
-        print_with_argv0(
-            "Can't find clang. Please install clang-3.5 or a later version.")
-        return 1
+        diagnostics.fatal(
+            "can't find clang (please install clang-3.5 or a later version)")
 
     if toolchain.cmake is None:
-        print_with_argv0("Can't find CMake. Please install CMake.")
-        return 1
+        diagnostics.fatal("can't find CMake (please install CMake)")
 
     if args.distcc:
         if toolchain.distcc is None:
-            print_with_argv0(
-                "Can't find distcc. Please install distcc")
-            return 1
+            diagnostics.fatal(
+                "can't find distcc (please install distcc)")
         if toolchain.distcc_pump is None:
-            print_with_argv0(
-                "Can't find distcc-pump. Please install distcc-pump")
-            return 1
+            diagnostics.fatal(
+                "can't find distcc-pump (please install distcc-pump)")
 
     if args.host_target is None or args.stdlib_deployment_targets is None:
-        print_with_argv0("Unknown operating system.")
-        return 1
+        diagnostics.fatal("unknown operating system")
 
     if args.symbols_package:
         if not os.path.isabs(args.symbols_package):
@@ -1024,10 +1018,9 @@ details of the setups of other systems or automated environments.""")
                 '(was \'{}\')'.format(args.symbols_package))
             return 1
         if not args.install_symroot:
-            print_with_argv0(
+            diagnostics.fatal(
                 "--install-symroot is required when specifying "
                 "--symbols-package.")
-            return 1
 
     if args.android:
         if args.android_ndk is None or \
@@ -1036,12 +1029,11 @@ details of the setups of other systems or automated environments.""")
                 args.android_icu_uc_include is None or \
                 args.android_icu_i18n is None or \
                 args.android_icu_i18n_include is None:
-            print_with_argv0("When building for Android, --android-ndk, "
-                             "--android-ndk-version, --android-icu-uc, "
-                             "--android-icu-uc-include, --android-icu-i18n, "
-                             "and --android-icu-i18n-include must be "
-                             "specified.")
-            return 1
+            diagnostics.fatal("when building for Android, --android-ndk, "
+                              "--android-ndk-version, --android-icu-uc, "
+                              "--android-icu-uc-include, --android-icu-i18n, "
+                              "and --android-icu-i18n-include must be "
+                              "specified")
 
     # Build cmark if any cmark-related options were specified.
     if (args.cmark_build_variant is not None):
@@ -1213,9 +1205,8 @@ details of the setups of other systems or automated environments.""")
 
     if args.build_ninja:
         if not os.path.exists(workspace.source_dir("ninja")):
-            print_with_argv0("Can't find source directory for ninja "
-                             "(tried %s)" % (workspace.source_dir("ninja")))
-            return 1
+            diagnostics.fatal("can't find source directory for ninja "
+                              "(tried %s)" % (workspace.source_dir("ninja")))
 
     os.umask(0o022)
 
@@ -1464,17 +1455,15 @@ details of the setups of other systems or automated environments.""")
 
 def main():
     if not SWIFT_SOURCE_ROOT:
-        print_with_argv0(
-            "Could not infer source root directory.  " +
-            "Forgot to set $SWIFT_SOURCE_ROOT environment variable?")
-        return 1
+        diagnostics.fatal(
+            "could not infer source root directory " +
+            "(forgot to set $SWIFT_SOURCE_ROOT environment variable?)")
 
     if not os.path.isdir(SWIFT_SOURCE_ROOT):
-        print_with_argv0(
-            "Source root directory \'" + SWIFT_SOURCE_ROOT +
-            "\' does not exist.  " +
-            "Forgot to set $SWIFT_SOURCE_ROOT environment variable?")
-        return 1
+        diagnostics.fatal(
+            "source root directory \'" + SWIFT_SOURCE_ROOT +
+            "\' does not exist " +
+            "(forgot to set $SWIFT_SOURCE_ROOT environment variable?)")
 
     # Determine if we are invoked in the preset mode and dispatch accordingly.
     if any([(opt.startswith("--preset") or opt == "--show-presets")

Diff for: utils/swift_build_support/swift_build_support/arguments.py

@@ -10,7 +10,7 @@
 #
 # ----------------------------------------------------------------------------
 """
-argparse suppliments
+argparse supplements
 """
 # ----------------------------------------------------------------------------
 

Diff for: utils/swift_build_support/swift_build_support/diagnostics.py

@@ -0,0 +1,32 @@
+# swift_build_support/diagnostics.py - Diagnostic Utilities     -*- python -*-
+#
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2016 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See http://swift.org/LICENSE.txt for license information
+# See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+#
+# ----------------------------------------------------------------------------
+
+import sys
+
+
+def note(message):
+    """
+    note(message)
+
+    Print a diagnostic notification to the standard output.
+    """
+    print(sys.argv[0] + ": note: " + message)
+    sys.stdout.flush()
+
+
+def fatal(message):
+    """
+    fatal(message)
+
+    Raise a fatal error.
+    """
+    raise SystemExit(sys.argv[0] + ": fatal error: " + message)