#
# -----------------------------------------------------------------------------
-ERROR_IF_UNSET = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
-ERROR_IF_EMPTY = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
-ERROR_IF_NONBOOL = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
+SHELL = /bin/sh
+
+ERROR_IF_UNSET ?= $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY ?= $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL ?= $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
# Default values of optionally user-supplied variables
DOXYGEN_CONF ?= Doxygen.conf
MSG_DOXYGEN_CMD := ' [DOXYGEN] :'
# Determine Doxygen invocation command
-BASE_DOXYGEN_CMD = ( cat $(DOXYGEN_CONF) $(DOXYGEN_OVERRIDE_PARAMS:%=; echo "%") ) | doxygen -
+BASE_DOXYGEN_CMD := ( cat $(DOXYGEN_CONF) $(DOXYGEN_OVERRIDE_PARAMS:%=; echo "%") ) | doxygen -
ifeq ($(DOXYGEN_FAIL_ON_WARNING), Y)
- DOXYGEN_CMD = if ( $(BASE_DOXYGEN_CMD) 2>&1 | grep -v "warning: ignoring unsupported tag" ;); then exit 1; fi;
+ DOXYGEN_CMD := if ( $(BASE_DOXYGEN_CMD) 2>&1 | grep -v "warning: ignoring unsupported tag" ;); then exit 1; fi;
else
- DOXYGEN_CMD = $(BASE_DOXYGEN_CMD)
+ DOXYGEN_CMD := $(BASE_DOXYGEN_CMD)
endif
doxygen: