aboutsummaryrefslogtreecommitdiff
path: root/depends/Makefile
diff options
context:
space:
mode:
Diffstat (limited to 'depends/Makefile')
-rw-r--r--depends/Makefile24
1 files changed, 24 insertions, 0 deletions
diff --git a/depends/Makefile b/depends/Makefile
index 5ad82bb56a..3d0784cb6b 100644
--- a/depends/Makefile
+++ b/depends/Makefile
@@ -4,6 +4,30 @@
print-%:
@echo $* = $($*)
+# When invoking a sub-make, keep only the command line variable definitions
+# matching the pattern in the filter function.
+#
+# e.g. invoking:
+# $ make A=1 C=1 print-MAKEOVERRIDES print-MAKEFLAGS
+#
+# with the following in the Makefile:
+# MAKEOVERRIDES := $(filter A=% B=%,$(MAKEOVERRIDES))
+#
+# will print:
+# MAKEOVERRIDES = A=1
+# MAKEFLAGS = -- A=1
+#
+# this is because as the GNU make manual says:
+# The command line variable definitions really appear in the variable
+# MAKEOVERRIDES, and MAKEFLAGS contains a reference to this variable.
+#
+# and since the GNU make manual also says:
+# variables defined on the command line are passed to the sub-make through
+# MAKEFLAGS
+#
+# this means that sub-makes will be invoked as if:
+# $(MAKE) A=1 blah blah
+MAKEOVERRIDES := $(filter V=%,$(MAKEOVERRIDES))
SOURCES_PATH ?= $(BASEDIR)/sources
WORK_PATH = $(BASEDIR)/work
BASE_CACHE ?= $(BASEDIR)/built