package/pkg-golang: catch use of legacy FOO_INSTALL_BINS

Signed-off-by: Yann E. MORIN <yann.morin@orange.com>
Cc: Christian Stewart <christian@aperture.us>
Reviewed-by: Romain Naour <romain.naour@smile.fr>
[Romain: update "Migrating to 2025.08" by "2025.11"]
Signed-off-by: Romain Naour <romain.naour@smile.fr>

docs/manual/migrating.adoc

@@ -222,3 +222,9 @@ from +-cargo2+ to +-cargo4+.
 In 2025.08, starting with systemd version 257, systemd-networkd requires kernel
 5.4 or later. If you are still using a kernel older than 5.4, please update
 your kernel or use an alternative network manager.
+
+[[migrating-golang-packages]]
+=== Migrating to 2025.11
+In 2025.11, the +FOO_INSTALL_BINS+ variable for golang packages is no longer
+supported; the list of binaries to install is automatically derived from
+the +FOO_BULD_TARGETS+ variable.

package/pkg-golang.mk

@@ -40,6 +40,12 @@ GO_BIN = $(HOST_DIR)/bin/go
 
 define inner-golang-package
 
+# Legacy
+ifneq ($$($(2)_INSTALL_BINS),)
+$$(error Package $(1) sets $(2)_INSTALL_BINS, which is no longer supported; \
+see the manual: https://buildroot.org/manual.html#migrating-golang-package )
+endif
+
 $(2)_BUILD_OPTS += \
 	-ldflags "$$($(2)_LDFLAGS)" \
 	-modcacherw \