build: add *_STANDARD vars to depends gen_id

Followup to #22380. We need to have these in the id so that we rebuild
if we change / unset a *_STANDARD.

depends/Makefile

@@ -144,8 +144,8 @@ include packages/packages.mk
 #     2. Before including packages/*.mk (excluding packages/packages.mk), since
 #        they rely on the build_id variables
 #
-build_id:=$(shell env CC='$(build_CC)' CXX='$(build_CXX)' AR='$(build_AR)' RANLIB='$(build_RANLIB)' STRIP='$(build_STRIP)' SHA256SUM='$(build_SHA256SUM)' DEBUG='$(DEBUG)' LTO='$(LTO)' ./gen_id '$(BUILD_ID_SALT)' 'GUIX_ENVIRONMENT=$(realpath $(GUIX_ENVIRONMENT))')
-$(host_arch)_$(host_os)_id:=$(shell env CC='$(host_CC)' CXX='$(host_CXX)' AR='$(host_AR)' RANLIB='$(host_RANLIB)' STRIP='$(host_STRIP)' SHA256SUM='$(build_SHA256SUM)' DEBUG='$(DEBUG)' LTO='$(LTO)' ./gen_id '$(HOST_ID_SALT)' 'GUIX_ENVIRONMENT=$(realpath $(GUIX_ENVIRONMENT))')
+build_id:=$(shell env CC='$(build_CC)' C_STANDARD='$(C_STANDARD)' CXX='$(build_CXX)' CXX_STANDARD='$(CXX_STANDARD)' AR='$(build_AR)' RANLIB='$(build_RANLIB)' STRIP='$(build_STRIP)' SHA256SUM='$(build_SHA256SUM)' DEBUG='$(DEBUG)' LTO='$(LTO)' ./gen_id '$(BUILD_ID_SALT)' 'GUIX_ENVIRONMENT=$(realpath $(GUIX_ENVIRONMENT))')
+$(host_arch)_$(host_os)_id:=$(shell env CC='$(host_CC)' C_STANDARD='$(C_STANDARD)' CXX='$(host_CXX)' CXX_STANDARD='$(CXX_STANDARD)' AR='$(host_AR)' RANLIB='$(host_RANLIB)' STRIP='$(host_STRIP)' SHA256SUM='$(build_SHA256SUM)' DEBUG='$(DEBUG)' LTO='$(LTO)' ./gen_id '$(HOST_ID_SALT)' 'GUIX_ENVIRONMENT=$(realpath $(GUIX_ENVIRONMENT))')
 
 qrencode_packages_$(NO_QR) = $(qrencode_$(host_os)_packages)
 

depends/gen_id

@@ -1,7 +1,8 @@
 #!/usr/bin/env bash
 
-# Usage: env [ CC=... ] [ CXX=... ] [ AR=... ] [ RANLIB=... ] [ STRIP=... ] \
-#            [ DEBUG=... ] [ LTO=... ] ./build-id [ID_SALT]...
+# Usage: env [ CC=... ] [ C_STANDARD=...] [ CXX=... ] [CXX_STANDARD=...] \
+#            [ AR=... ] [ RANLIB=... ] [ STRIP=... ] [ DEBUG=... ] \
+#            [ LTO=... ] ./build-id [ID_SALT]...
 #
 # Prints to stdout a SHA256 hash representing the current toolset, used by
 # depends/Makefile as a build id for caching purposes (detecting when the
@@ -39,12 +40,14 @@
     bash -c "${CC} -v"
     bash -c "${CC} -v -E -xc -o /dev/null - < /dev/null"
     bash -c "${CC} -v -E -xobjective-c -o /dev/null - < /dev/null"
+    echo "C_STANDARD=${C_STANDARD}"
     echo "END CC"
 
     echo "BEGIN CXX"
     bash -c "${CXX} -v"
     bash -c "${CXX} -v -E -xc++ -o /dev/null - < /dev/null"
     bash -c "${CXX} -v -E -xobjective-c++ -o /dev/null - < /dev/null"
+    echo "CXX_STANDARD=${CXX_STANDARD}"
     echo "END CXX"
 
     echo "BEGIN AR"