[gnome-builder] autotools: Fix build target discovery for flatpak runtimes

[Christian Hergert <chergert src gnome org>]

commit e4e2e7580a39b9c448529626f6ba9a7e5730e05a
Author: Matthew Leeds <mleeds redhat com>
Date:   Sat Nov 5 19:28:19 2016 -0500

    autotools: Fix build target discovery for flatpak runtimes
    
    ide_makecache_get_build_targets_worker() tries to find build targets by
    spawning make processes in each directory with a Makefile, but since
    the flatpak-build command specifies the directory it is unaffected by
    the process's cwd. So finding build targets in subdirectories fails for
    flatpak runtimes. This commit fixes that by using the -C option on make
    to switch to the appropriate subdirectory.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=773764

 libide/subprocess/ide-subprocess-launcher.c |   15 +++++++++++
 libide/subprocess/ide-subprocess-launcher.h |    3 ++
 plugins/autotools/ide-makecache.c           |   36 ++++++++++++++++++++++++---
 3 files changed, 50 insertions(+), 4 deletions(-)
---
diff --git a/libide/subprocess/ide-subprocess-launcher.c b/libide/subprocess/ide-subprocess-launcher.c
index f679317..7f04cf6 100644
--- a/libide/subprocess/ide-subprocess-launcher.c
+++ b/libide/subprocess/ide-subprocess-launcher.c
@@ -833,3 +833,18 @@ ide_subprocess_launcher_insert_argv (IdeSubprocessLauncher *self,
 
   g_ptr_array_insert (priv->argv, index, g_strdup (arg));
 }
+
+void
+ide_subprocess_launcher_replace_argv (IdeSubprocessLauncher *self,
+                                      guint                  index,
+                                      const gchar           *arg)
+{
+  IdeSubprocessLauncherPrivate *priv = ide_subprocess_launcher_get_instance_private (self);
+
+  g_return_if_fail (IDE_IS_SUBPROCESS_LAUNCHER (self));
+  g_return_if_fail (index < priv->argv->len);
+  g_return_if_fail (arg != NULL);
+
+  g_ptr_array_remove_index (priv->argv, index);
+  g_ptr_array_insert (priv->argv, (index == priv->argv->len ? -1 : index), g_strdup (arg));
+}
diff --git a/libide/subprocess/ide-subprocess-launcher.h b/libide/subprocess/ide-subprocess-launcher.h
index bf389b8..69b5f0e 100644
--- a/libide/subprocess/ide-subprocess-launcher.h
+++ b/libide/subprocess/ide-subprocess-launcher.h
@@ -72,6 +72,9 @@ void                   ide_subprocess_launcher_setenv              (IdeSubproces
 void                   ide_subprocess_launcher_insert_argv         (IdeSubprocessLauncher  *self,
                                                                     guint                   index,
                                                                     const gchar            *arg);
+void                   ide_subprocess_launcher_replace_argv        (IdeSubprocessLauncher  *self,
+                                                                    guint                   index,
+                                                                    const gchar            *arg);
 void                   ide_subprocess_launcher_overlay_environment (IdeSubprocessLauncher  *self,
                                                                     IdeEnvironment         *environment);
 const gchar * const   *ide_subprocess_launcher_get_argv            (IdeSubprocessLauncher  *self);
diff --git a/plugins/autotools/ide-makecache.c b/plugins/autotools/ide-makecache.c
index 3473ea2..70e9a99 100644
--- a/plugins/autotools/ide-makecache.c
+++ b/plugins/autotools/ide-makecache.c
@@ -1872,6 +1872,9 @@ ide_makecache_get_build_targets_worker (GTask        *task,
   gchar *line;
   gsize line_len;
   IdeLineReader reader;
+  const gchar * const * partial_argv;
+  guint num_args;
+  gboolean first_subdir = TRUE;
 
   IDE_ENTRY;
 
@@ -1921,6 +1924,11 @@ ide_makecache_get_build_targets_worker (GTask        *task,
     make_name = GNU_MAKE_NAME;
 
   ide_subprocess_launcher_push_argv (launcher, make_name);
+
+  /* Find the argv index so we can insert arguments on each run */
+  partial_argv = ide_subprocess_launcher_get_argv (launcher);
+  for (num_args = 0; partial_argv[num_args] != NULL; num_args++) ;
+
   ide_subprocess_launcher_push_argv (launcher, "-f");
   ide_subprocess_launcher_push_argv (launcher, "-");
   ide_subprocess_launcher_push_argv (launcher, "print-bindir");
@@ -1969,16 +1977,36 @@ ide_makecache_get_build_targets_worker (GTask        *task,
     {
       g_autoptr(IdeSubprocess) subprocess = NULL;
       g_autoptr(GHashTable) amdirs = NULL;
-      g_autofree gchar *path = NULL;
+      g_autofree gchar *rel_path = NULL;
       GFile *makedir;
 
       /*
        * Make sure we are running within the directory containing the
-       * Makefile that we care about.
+       * Makefile that we care about. We use make's -C option because
+       * for runtimes such as flatpak make doesn't necessarily run in
+       * the same directory as the process.
        */
       makedir = g_ptr_array_index (makedirs, j);
-      path = g_file_get_path (makedir);
-      ide_subprocess_launcher_set_cwd (launcher, path);
+      rel_path = g_file_get_relative_path (build_dir, makedir);
+      if (rel_path == NULL)
+        {
+          g_autofree gchar *path = NULL;
+          path = g_file_get_path (makedir);
+          ide_subprocess_launcher_set_cwd (launcher, path);
+        }
+      else
+        {
+          if (first_subdir)
+            {
+              ide_subprocess_launcher_insert_argv (launcher, num_args, "-C");
+              ide_subprocess_launcher_insert_argv (launcher, (num_args + 1), rel_path);
+              first_subdir = FALSE;
+            }
+          else
+            {
+              ide_subprocess_launcher_replace_argv (launcher, (num_args + 1), rel_path);
+            }
+        }
 
       /*
        * Spawn make, waiting for our stdin input which will add our debug