Import ostree's compiler warnings, fix up callers

In ostree I maintain what I consider a "baseline" set of compiler
warnings that should *always* be fatal for a modern C project.

I noticed while working on a previous patch that a `-Werror=format`
warning wasn't fatal.

There are a few that are really, really important like
`-Werror=missing-prototypes`. I also take some like `-Werror=misleading-indentation`
which already caught some bugs.  See also https://lwn.net/Articles/678019/

.gitignore

@@ -24,6 +24,7 @@ libtool
 ltmain.sh
 m4/*.m4
 !m4/glibtests.m4
+!m4/attributes.m4
 missing
 stamp-h1
 config.h.in

Makefile.am

@@ -53,6 +53,8 @@ AM_CPPFLAGS = \
  -I$(builddir)/lib \
  $(NULL)
 
+AM_CFLAGS = $(WARN_CFLAGS)
+
 if WITH_SYSTEM_BWRAP
 AM_CPPFLAGS += -DHELPER=\"$(BWRAP)\"
 else

common/flatpak-dir.c

@@ -576,7 +576,7 @@ flatpak_get_user_base_dir_location (void)
  return g_object_ref ((GFile *)file);
 }
 
-GFile *
+static GFile *
 flatpak_get_user_cache_dir_location (void)
 {
  g_autoptr(GFile) base_dir = NULL;
@@ -585,7 +585,7 @@ flatpak_get_user_cache_dir_location (void)
  return g_file_get_child (base_dir, "system-cache");
 }
 
-GFile *
+static GFile *
 flatpak_ensure_user_cache_dir_location (GError **error)
 {
  g_autoptr(GFile) cache_dir = NULL;
@@ -603,7 +603,7 @@ flatpak_ensure_user_cache_dir_location (GError **error)
  return g_steal_pointer (&cache_dir);
 }
 
-GFile *
+static GFile *
 flatpak_ensure_oci_summary_cache_dir_location (GError **error)
 {
  g_autoptr(GFile) cache_dir = NULL;
@@ -658,7 +658,7 @@ flatpak_dir_get_system_helper (FlatpakDir *self)
  return NULL;
 }
 
-gboolean
+static gboolean
 flatpak_dir_use_system_helper (FlatpakDir *self,
  const char *installing_from_remote)
 {
@@ -2921,7 +2921,7 @@ flatpak_dir_set_active (FlatpakDir *self,
  return ret;
 }
 
-gboolean
+static gboolean
 flatpak_dir_run_triggers (FlatpakDir *self,
  GCancellable *cancellable,
  GError **error)
@@ -3349,7 +3349,7 @@ rewrite_export_dir (const char *app,
  return ret;
 }
 
-gboolean
+static gboolean
 flatpak_rewrite_export_dir (const char *app,
  const char *branch,
  const char *arch,
@@ -3467,7 +3467,7 @@ export_dir (int source_parent_fd,
  return ret;
 }
 
-gboolean
+static gboolean
 flatpak_export_dir (GFile *source,
  GFile *destination,
  const char *symlink_prefix,
@@ -6146,7 +6146,7 @@ find_matching_ref (GHashTable *refs,
  parts[3]));
  }
 
- flatpak_fail (error, err->str);
+ flatpak_fail (error, "%s", err->str);
  return NULL;
  }
 
@@ -6606,7 +6606,7 @@ flatpak_dir_remote_has_deploys (FlatpakDir *self,
  return FALSE;
 }
 
-gint
+static gint
 cmp_remote (gconstpointer a,
  gconstpointer b,
  gpointer user_data)

common/flatpak-run.c

@@ -497,7 +497,7 @@ flatpak_context_set_system_bus_policy (FlatpakContext *context,
  g_hash_table_insert (context->system_bus_policy, g_strdup (name), GINT_TO_POINTER (policy));
 }
 
-void
+static void
 flatpak_context_apply_generic_policy (FlatpakContext *context,
  const char *key,
  const char *value)
@@ -2075,7 +2075,7 @@ create_proxy_socket (char *template)
  return g_steal_pointer (&proxy_socket);
 }
 
-gboolean
+static gboolean
 flatpak_run_add_system_dbus_args (FlatpakContext *context,
  char ***envp_p,
  GPtrArray *argv_array,
@@ -2127,7 +2127,7 @@ flatpak_run_add_system_dbus_args (FlatpakContext *context,
  return FALSE;
 }
 
-gboolean
+static gboolean
 flatpak_run_add_session_dbus_args (GPtrArray *argv_array,
  char ***envp_p,
  GPtrArray *dbus_proxy_argv,
@@ -3487,7 +3487,7 @@ add_document_portal_args (GPtrArray *argv_array,
  }
 }
 
-gchar *
+static gchar *
 join_args (GPtrArray *argv_array, gsize *len_out)
 {
  gchar *string;

common/flatpak-utils.c

@@ -285,7 +285,7 @@ flatpak_path_match_prefix (const char *pattern,
  return NULL; /* Should not be reached */
 }
 
-const char *
+static const char *
 flatpak_get_kernel_arch (void)
 {
  static struct utsname buf;
@@ -858,7 +858,7 @@ flatpak_kinds_from_bools (gboolean app, gboolean runtime)
  return kinds;
 }
 
-gboolean
+static gboolean
 _flatpak_split_partial_ref_arg (const char *partial_ref,
  gboolean validate,
  FlatpakKinds default_kinds,
@@ -4695,9 +4695,13 @@ flatpak_yes_no_prompt (const char *prompt, ...)
  va_list var_args;
  gchar *s;
 
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
  va_start (var_args, prompt);
  s = g_strdup_vprintf (prompt, var_args);
  va_end (var_args);
+#pragma GCC diagnostic pop
 
  while (TRUE)
  {
@@ -5098,9 +5102,12 @@ flatpak_complete_word (FlatpakCompletion *completion,
 
  g_return_if_fail (format != NULL);
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
  va_start (args, format);
  string = g_strdup_vprintf (format, args);
  va_end (args);
+#pragma GCC diagnostic pop
 
  if (!g_str_has_prefix (string, completion->cur))
  return;
@@ -5144,7 +5151,7 @@ flatpak_complete_ref (FlatpakCompletion *completion,
  }
 }
 
-int
+static int
 find_current_element (const char *str)
 {
  int count = 0;

common/flatpak-utils.h

@@ -579,8 +579,8 @@ gboolean flatpak_allocate_tmpdir (int tmpdir_dfd,
  GError **error);
 
 
-gboolean flatpak_yes_no_prompt (const char *prompt, ...);
-long flatpak_number_prompt (int min, int max, const char *prompt, ...);
+gboolean flatpak_yes_no_prompt (const char *prompt, ...) G_GNUC_PRINTF(1, 2);
+long flatpak_number_prompt (int min, int max, const char *prompt, ...) G_GNUC_PRINTF(3, 4);
 
 typedef void (*FlatpakLoadUriProgress) (guint64 downloaded_bytes,
  gpointer user_data);
@@ -621,7 +621,7 @@ FlatpakCompletion *flatpak_completion_new (const char *arg_line,
  const char *arg_cur);
 void flatpak_complete_word (FlatpakCompletion *completion,
  char *format,
- ...);
+ ...) G_GNUC_PRINTF(2,3);
 void flatpak_complete_ref (FlatpakCompletion *completion,
  OstreeRepo *repo);
 void flatpak_complete_partial_ref (FlatpakCompletion *completion,

configure.ac

@@ -55,12 +55,26 @@ AC_DEFINE_UNQUOTED(GETTEXT_PACKAGE, "$PACKAGE", [gettext domain])
 AM_SILENT_RULES([yes])
 AM_MAINTAINER_MODE([enable])
 
-if test "x$GCC" = "xyes"; then
- case " $CFLAGS " in
- *[[\ \ ]]-Wall[[\ \ ]]*) ;;
- *) CFLAGS="$CFLAGS -Wall" ;;
- esac
-fi
+dnl This list is shared with https://github.com/ostreedev/ostree
+CC_CHECK_FLAGS_APPEND([WARN_CFLAGS], [CFLAGS], [\
+-pipe \
+-Wall \
+-Werror=empty-body \
+-Werror=strict-prototypes \
+-Werror=missing-prototypes \
+-Werror=implicit-function-declaration \
+"-Werror=format=2 -Werror=format-security -Werror=format-nonliteral" \
+-Werror=pointer-arith -Werror=init-self \
+-Werror=missing-declarations \
+-Werror=return-type \
+-Werror=overflow \
+-Werror=int-conversion \
+-Werror=parenthesis \
+-Werror=incompatible-pointer-types \
+-Werror=misleading-indentation \
+-Werror=missing-include-dirs -Werror=aggregate-return \
+])
+AC_SUBST(WARN_CFLAGS)
 
 AX_VALGRIND_CHECK
 

lib/flatpak-installed-ref.c

@@ -24,6 +24,7 @@
 
 #include "flatpak-utils.h"
 #include "flatpak-installed-ref.h"
+#include "flatpak-installed-ref-private.h"
 #include "flatpak-enum-types.h"
 
 /**

lib/flatpak-related-ref.c

@@ -24,6 +24,7 @@
 
 #include "flatpak-utils.h"
 #include "flatpak-related-ref.h"
+#include "flatpak-related-ref-private.h"
 #include "flatpak-enum-types.h"
 
 /**