depends: libX*: --disable-malloc0returnsnull in conf

Author: dongcarl

depends/packages/libX11.mk

@@ -6,8 +6,9 @@ $(package)_sha256_hash=2aa027e837231d2eeea90f3a4afe19948a6eb4c8b2bec0241eba7dbc8
 $(package)_dependencies=libxcb xtrans xextproto xproto
 
 define $(package)_set_vars
-$(package)_config_opts=--disable-xkb --disable-static
-$(package)_config_opts_linux=--with-pic
+  # See libXext for --disable-malloc0returnsnull rationale.
+  $(package)_config_opts=--disable-xkb --disable-static --disable-malloc0returnsnull
+  $(package)_config_opts_linux=--with-pic
 endef
 
 define $(package)_preprocess_cmds

depends/packages/libXext.mk

@@ -6,7 +6,30 @@ $(package)_sha256_hash=b518d4d332231f313371fdefac59e3776f4f0823bcb23cf7c7305bfb5
 $(package)_dependencies=xproto xextproto libX11 libXau
 
 define $(package)_set_vars
-  $(package)_config_opts=--disable-shared
+  # A number of steps in the autoconfig process implicitly assume that the build
+  # system and the host system are the same. For example, library components
+  # want to build and run test programs to determine the behavior of certain
+  # host system elements. This is clearly impossible when crosscompiling. To
+  # work around these issues, the --enable-malloc0returnsnull (or
+  # --disable-malloc0returnsnull, depending on the host system) must be passed
+  # to configure.
+  #                                -- https://www.x.org/wiki/CrossCompilingXorg/
+  #
+  # Concretely, between the releases of libXext 1.3.2 and 1.3.3,
+  # XORG_CHECK_MALLOC_ZERO from xorg-macros was changed to use the autoconf
+  # cache, expecting cross-compilation environments to seed this cache as there
+  # is no single correct value when cross compiling (think uclibc, musl, etc.).
+  # You can see the actual change in commit 72fdc868b56fe2b7bdc9a69872651baeca72
+  # in the freedesktop/xorg-macros repo.
+  #
+  # As a result of this change, if we don't seed the cache and we don't use
+  # either --{en,dis}able-malloc0returnsnull, the AC_RUN_IFELSE block has no
+  # optional action-if-cross-compiling argument and configure prints an error
+  # message and exits as documented in the autoconf manual. Prior to this
+  # commit, the AC_RUN_IFELSE block had an action-if-cross-compiling argument
+  # which set the more pessimistic default value MALLOC_ZERO_RETURNS_NULL=yes.
+  # This is why the flag was not required prior to libXext 1.3.3.
+  $(package)_config_opts=--disable-static --disable-malloc0returnsnull
 endef
 
 define $(package)_preprocess_cmds