[gnome-builder/gnome-builder-3-32] foundry: locate build flags from environment when possible

[Christian Hergert <chergert src gnome org>]

commit bcc1b01d364342381df21a151786ec3b1fe8634a
Author: Giovanni Campagna <gcampagn cs stanford edu>
Date:   Thu Apr 18 09:27:27 2019 -0700

    foundry: locate build flags from environment when possible
    
    If the build system is limited and cannot mine build flags, use the
    CFLAGS/CXXFLAGS environment variables set in the build configuration.
    
    This allows users to use custom build systems and still have proper
    diagnostics and code completion, if they fill in their .buildconfig
    correctly.

 src/libide/foundry/ide-build-system.c | 77 +++++++++++++++++++++++++++++++----
 1 file changed, 70 insertions(+), 7 deletions(-)
---
diff --git a/src/libide/foundry/ide-build-system.c b/src/libide/foundry/ide-build-system.c
index b3440d0da..8baa6506c 100644
--- a/src/libide/foundry/ide-build-system.c
+++ b/src/libide/foundry/ide-build-system.c
@@ -86,13 +86,76 @@ ide_build_system_real_get_build_flags_async (IdeBuildSystem      *self,
                                              GAsyncReadyCallback  callback,
                                              gpointer             user_data)
 {
-  ide_task_report_new_error (self,
-                             callback,
-                             user_data,
-                             ide_build_system_real_get_build_flags_async,
-                             G_IO_ERROR,
-                             G_IO_ERROR_NOT_SUPPORTED,
-                             "Fetching build flags is not supported");
+  g_autoptr(IdeContext) context = NULL;
+  g_autoptr(IdeTask) task = NULL;
+  g_autoptr(GError) error = NULL;
+  g_auto(GStrv) parsed_flags = NULL;
+  IdeBuildManager *build_manager;
+  IdeEnvironment *env;
+  const gchar *flags = NULL;
+  const gchar *path;
+  IdePipeline *pipeline;
+  IdeConfig *config;
+
+  g_assert (IDE_IS_MAIN_THREAD ());
+  g_assert (IDE_IS_BUILD_SYSTEM (self));
+  g_assert (G_IS_FILE (file));
+  g_assert (!cancellable || G_IS_CANCELLABLE (cancellable));
+
+  task = ide_task_new (self, cancellable, callback, user_data);
+  ide_task_set_source_tag (task, ide_build_system_real_get_build_flags_async);
+
+  /* Avoid work immediately if we can */
+  if (ide_task_return_error_if_cancelled (task))
+    return;
+
+  if (!g_file_is_native (file) || !(path = g_file_peek_path (file)))
+    {
+      ide_task_return_new_error (task,
+                                 G_IO_ERROR,
+                                 G_IO_ERROR_NOT_SUPPORTED,
+                                 "Cannot get build flags for non-native file");
+      return;
+    }
+
+  if (!(context = ide_object_ref_context (IDE_OBJECT (self))) ||
+      !(build_manager = ide_build_manager_from_context (context)) ||
+      !(pipeline = ide_build_manager_get_pipeline (build_manager)) ||
+      !(config = ide_pipeline_get_config (pipeline)) ||
+      !(env = ide_config_get_environment (config)))
+    {
+      ide_task_return_new_error (task,
+                                 G_IO_ERROR,
+                                 G_IO_ERROR_NOT_INITIALIZED,
+                                 "Cannot access build flags without build config");
+      return;
+    }
+
+  if (ide_path_is_cpp_like (path))
+    {
+      flags = ide_environment_getenv (env, "CXXFLAGS");
+    }
+  else if (ide_path_is_c_like (path))
+    {
+      if (!(flags = ide_environment_getenv (env, "CFLAGS")))
+        flags = ide_environment_getenv (env, "CXXFLAGS");
+    }
+  else
+    {
+      ide_task_return_new_error (task,
+                                 G_IO_ERROR,
+                                 G_IO_ERROR_NOT_SUPPORTED,
+                                 "Cannot extract build flags for unknown file type: \"%s\"",
+                                 path);
+    }
+
+  if (flags == NULL)
+    flags = "";
+
+  if (!g_shell_parse_argv (flags, NULL, &parsed_flags, &error))
+    ide_task_return_error (task, g_steal_pointer (&error));
+  else
+    ide_task_return_pointer (task, g_steal_pointer (&parsed_flags), g_strfreev);
 }
 
 static gchar **