From 212374149f7c957ea25ea12404f92c625fdc211a Mon Sep 17 00:00:00 2001
From: Stefano Pigozzi <stefano.pigozzi@gmail.com>
Date: Mon, 4 Aug 2014 10:44:21 +0200
Subject: build: expose waf variants to the user

This allows the user to execute multiple configuration and build steps. It
can be used for several scenarios where you need different compiler flags.
---
 waftools/generators/headers.py |  8 ++++++++
 wscript                        | 27 +++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/waftools/generators/headers.py b/waftools/generators/headers.py
index b38fcb88f4..bd28befd99 100644
--- a/waftools/generators/headers.py
+++ b/waftools/generators/headers.py
@@ -1,3 +1,9 @@
+def __cp_to_variant__(ctx, variant, basename):
+    src = ctx.bldnode.search(basename).read()
+    node = ctx.bldnode.make_node("{0}/{1}".format(variant, basename))
+    node.parent.mkdir()
+    node.write(src)
+
 def __get_version__(ctx):
     import subprocess
     process = subprocess.Popen(["sh", "./version.sh", "--print"],
@@ -17,6 +23,7 @@ def __get_build_date__():
 def __write_config_h__(ctx):
     ctx.start_msg("Writing configuration header:")
     ctx.write_config_header('config.h')
+    __cp_to_variant__(ctx, ctx.options.variant, 'config.h')
     ctx.end_msg("config.h", "PINK")
 
 def __write_version_h__(ctx):
@@ -25,6 +32,7 @@ def __write_version_h__(ctx):
     ctx.define("VERSION",   ctx.env.VERSION)
     ctx.define("BUILDDATE", __get_build_date__())
     ctx.write_config_header("version.h")
+    __cp_to_variant__(ctx, ctx.options.variant, 'version.h')
     ctx.end_msg("version.h", "PINK")
 
 def __add_mplayer_defines__(ctx):
diff --git a/wscript b/wscript
index ee1ece5744..e0d71235e5 100644
--- a/wscript
+++ b/wscript
@@ -773,6 +773,10 @@ def options(opt):
             help    = 'directory for installing {0} [{1}]' \
                       .format(desc, default))
 
+    group.add_option('--variant',
+        default = '',
+        help    = 'variant name for saving configuration and build results')
+
     opt.parse_features('build and install options', build_options)
     optional_features = main_dependencies + libav_dependencies
     opt.parse_features('optional feaures',  optional_features)
@@ -798,6 +802,7 @@ def is_debug_build(ctx):
     return getattr(ctx.options, 'enable_debug-build')
 
 def configure(ctx):
+    ctx.resetenv(ctx.options.variant)
     ctx.check_waf_version(mini='1.7.15')
     target = os.environ.get('TARGET')
     (cc, pkg_config, windres) = ('cc', 'pkg-config', 'windres')
@@ -858,5 +863,27 @@ def configure(ctx):
     ctx.store_dependencies_lists()
 
 def build(ctx):
+    if ctx.options.variant not in ctx.all_envs:
+        from waflib import Errors
+        raise Errors.WafError(
+            'The project was not configured: run "waf --variant={0} configure" first!'
+                .format(ctx.options.variant))
     ctx.unpack_dependencies_lists()
     ctx.load('wscript_build')
+
+def init(ctx):
+    from waflib.Build import BuildContext, CleanContext, InstallContext, UninstallContext
+    for y in (BuildContext, CleanContext, InstallContext, UninstallContext):
+        class tmp(y):
+            variant = ctx.options.variant
+
+    # This is needed because waf initializes the ConfigurationContext with
+    # an arbitrary setenv('') which would rewrite the previous configuration
+    # cache for the default variant if the configure step finishes.
+    # Ideally ConfigurationContext should just let us override this at class
+    # level like the other Context subclasses do with variant
+    from waflib.Configure import ConfigurationContext
+    class cctx(ConfigurationContext):
+        def resetenv(self, name):
+            self.all_envs = {}
+            self.setenv(name)
-- 
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