From: Matt McCutchen <hashproduct@gmail.com>
Date: Thu, 14 Jun 2007 02:11:41 +0000 (-0400)
Subject: Changes necessary and proper to get mgear to build rsync:
X-Git-Url: https://mattmccutchen.net/mgear/mgear.git/commitdiff_plain/0382f3351db8ba1e76ce006859783b7d49622892

Changes necessary and proper to get mgear to build rsync:
- $(mg-define-rule) now takes the name of the variable holding the command
  instead of the command itself.  This generally saves the user a $(value).
- I changed my mind again: $@ in a command is translated to the temp file rather
  than the eventual target.
- Handle commas in commands better.
- Enforce that all files are secondary.
---

diff --git a/demo/Makefile b/demo/Makefile
index 7eb0502..ff220b6 100644
--- a/demo/Makefile
+++ b/demo/Makefile
@@ -6,11 +6,11 @@ include mgear.mk
 
 all:
 
-cmd-xgrep = grep 'X' '$<' >'$t' && echo "Hello world from xgrep"
-$(call mg-define-rule,%.x,%,$(value cmd-xgrep))
+cmd-xgrep = grep 'X' '$<' >'$@' && echo "Hello world from xgrep"
+$(call mg-define-rule,%.x,%,cmd-xgrep)
 
-cmd-addheader = echo 'Header:' | cat - '$<' >'$t'
-$(call mg-define-rule,%.h,%,$(value cmd-addheader))
+cmd-addheader = echo 'Header:' | cat - '$<' >'$@'
+$(call mg-define-rule,%.h,%,cmd-addheader)
 
 # Testing obfuscation
 mainoid := $(newoid)
diff --git a/mgear.mk b/mgear.mk
index 7eb2877..cccdbc2 100644
--- a/mgear.mk
+++ b/mgear.mk
@@ -10,11 +10,16 @@ mg-orig-default-goal:=$(.DEFAULT_GOAL)
 # instead of trying to anticipate which prerequisites it will need in advance.
 .SECONDEXPANSION:
 
+# Deletion of intermediate files messes everything up.
+# TODO: See if we can relax this requirement.
+.SECONDARY:
+
 
 # TEXT UTILITIES
 empty:=
 bs:=\$(empty)
 hash:=\#
+comma:=,
 pct:=%
 define nl
 
@@ -25,6 +30,9 @@ sq='$(subst ','\'',$1)'
 # Make-quote: a$\nb => a$$$(nl)b
 # This is enough to assign the value, *but not to use it as an argument!*
 mqas=$(subst $(hash),$$(hash),$(subst $(nl),$$(nl),$(subst $$,$$$$,$1)))
+# Make the value safe to use as an argument without doubling $.
+# *The implementation is incomplete*; I will improve it as needed.
+msarg=$(subst $(comma),$$(comma),$1)
 # Return nonempty if the strings are equal, empty otherwise.
 # If the strings have only nice characters, you can do $(filter x$1,x$2).
 streq=$(findstring x$1,$(findstring x$2,x$1))
@@ -171,8 +179,8 @@ $(mg-scout-oid)@opr:=
 $(mg-scout-oid)@ocmd:=
 
 # Mgear-ized automatic variables.
-# $@: needs no translation
-# NOTE: $(mg@) is *eventual* target.  Commands must write to temp file, $t .
+# For now, if you really want the eventual target, write $$(@).
+mg@ = $@.tmp
 # $%: haven't thought about it much, but probably needs no translation
 mg< = $(firstword $(mg^))
 mg? = $(filter-out $(opfx)%,$($@@gq))
@@ -181,11 +189,11 @@ mg+ = $(filter-out MG-% $(opfx)%,$+)
 # $|: needs no translation
 # $*: needs no translation
 
-# $(call mg-translate-cmd,cat $$< >$$t)
+# $(call mg-translate-cmd,cat $$< >$$@)
 # Replaces references to automatic variables with references to their mgear-ized
 # counterparts.  There might be false matches, e.g., $$@ => $$(mg@) ;
 # to prevent that, write $$$(empty)@ instead.  (c.f. autoconf empty quadrigraph)
-mg-translate-cmd=$(subst $$t,$$@.tmp,$(subst $$?,$$(mg?),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1)))))
+mg-translate-cmd=$(subst $$@,$$(mg@),$(subst $$?,$$(mg?),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1)))))
 
 # $(call mg-prereq-predict,target,prerequisites)
 # Expands to code that does the following at second-expansion time:
@@ -204,9 +212,10 @@ mg-prereq-predict=$$$$(call mg-set-gdeps,$$$$+ $(if $(findstring /,$1),$$$$(subs
 MG-FORCE:
 .PHONY: MG-FORCE
 
-# $(call mg-define-rule,target,prerequisites,cmd)
-# Defines a rule.  cmd is expanded again when it is run, at which time
-# Mgear-ized automatic variables are available.
+# $(call mg-define-rule,target,prerequisites,cmdvar)
+# Defines a rule.  cmdvar is *the name of a variable* containing the command.  
+# The variable is read immediately with $(value) and then expanded in the scope
+# of mgear-ized automatic variables each time the rule is run.
 #
 # I eradicated the target-specific variables because they fail when there are
 # multiple implicit rules with the same target pattern.
@@ -216,7 +225,7 @@ MG-FORCE:
 # $(bar@gq).
 define mg-define-rule
 $(eval $1: $(call mg-prereq-predict,$1,$2) $2 MG-FORCE $(mg-genfile-oid)$(aname)$$$$@.g
-	$$(call mg-rule-cmd,$(call mg-translate-cmd,$3)))
+	$$(call mg-rule-cmd,$(call msarg,$(call mg-translate-cmd,$(value $3)))))
 endef
 
 # TODO Provide a way to define static pattern rules.
diff --git a/testsuite b/testsuite
index 8cb46a0..f7ec807 100755
--- a/testsuite
+++ b/testsuite
@@ -56,7 +56,7 @@ function assert_saw {
 }
 function assert_not_saw {
 	if ! grep -q "$@" mgear.log; then
-		echo "Good, saw '${@:$#}' in build log."
+		echo "Good, didn't see '${@:$#}' in build log."
 	else
 		echo "Did not expect '${@:$#}' in build log but saw it!"
 		fail
@@ -118,8 +118,10 @@ include mgear.mk
 .SECONDARY:
 
 include hc-rule.mk
-$(call mg-define-rule,%,%.ssc,sleep 1 && grep 'warn' $$< && sed -e 's_//.*$$$$__' $$< >$$t)
-$(call mg-define-rule,index,index.in,sort $$< >$$t)
+cmd-ssc=sleep 1 && grep 'warn' $< && sed -e 's_//.*$$__' $< >$@
+$(call mg-define-rule,%,%.ssc,cmd-ssc)
+cmd-index=sort $< >$@
+$(call mg-define-rule,index,index.in,cmd-index)
 
 clean:
 	$(call mg-clean-cmd,.)
@@ -127,7 +129,8 @@ clean:
 EOF
 
 cat >hc-rule.mk <<'EOF'
-$(call mg-define-rule,%,%.hc,sed -e 's_#.*$$$$__' $$< >$$t)
+cmd-hc=sed -e 's_$(hash).*$$__' $< >$@
+$(call mg-define-rule,%,%.hc,cmd-hc)
 EOF
 
 # Input files.
@@ -218,10 +221,12 @@ EOF
 
 # Change the rule for # comments to strip spaces before a #.
 # Make sure foo is updated properly.
+# Also, make sure commas in commands work properly.
 
 start_section "Command change for % <- %.hc"
 cat >hc-rule.mk <<'EOF'
-$(call mg-define-rule,%,%.hc,sed -e 's_ *#.*$$$$__' $$< >$$t)
+cmd-hc=sed -e 's, *$(hash).*$$,,' $< >$@
+$(call mg-define-rule,%,%.hc,cmd-hc)
 EOF
 do_mgear foo