Auto merge of #24315 - richo:make-debug-helper, r=pnkfelix

bors · bors · commit 0cf99c3e06e8 · 2015-04-13T02:50:13.000Z
Also add docs because not being able to discover these things is the pits. This was lifted from http://blog.jgc.org/2015/04/the-one-line-you-should-add-to-every.html , and solves a problem I've solved myself a *lot* of times, often in massively inferior ways. Super open to documenting it somewhere other than nitty-gritty, which isn't immediately obvious.
diff --git a/Makefile.in b/Makefile.in
@@ -159,6 +159,13 @@
 #
 # Admittedly this is a little convoluted.
 #
+# If you find yourself working on the make infrastructure itself, and trying to
+# find the value of a given variable after expansion, you can use:
+#
+# make print-VARIABLE_NAME
+#
+# To extract it
+#
 # </nitty-gritty>
 #
 
diff --git a/mk/util.mk b/mk/util.mk
@@ -16,4 +16,7 @@ else
   E = echo $(1)
 endif
 
+print-%:
+	@echo $*=$($*)
+
 S := $(CFG_SRC_DIR)

Original file line number	Diff line number	Diff line change
`@@ -159,6 +159,13 @@`
`159`	`159`	`#`
`160`	`160`	`# Admittedly this is a little convoluted.`
`161`	`161`	`#`
	`162`	`+# If you find yourself working on the make infrastructure itself, and trying to`
	`163`	`+# find the value of a given variable after expansion, you can use:`
	`164`	`+#`
	`165`	`+# make print-VARIABLE_NAME`
	`166`	`+#`
	`167`	`+# To extract it`
	`168`	`+#`
`162`	`169`	`# </nitty-gritty>`
`163`	`170`	`#`
`164`	`171`