Build system: always use `make -r`

Do what this comment was suggesting:

    "Ideally we'd like to have 'make -r' turned on by default, because
    that disables all the implicit rules, but there doesn't seem to be a
    good way to do that."

This change doesn't seem to have much effect on the time it takes to run
make. Apparently clearing .SUFFIXES was enough for that. But it does
make the output of `make -d` quite a bit shorter, which is nice.

Note: ghc.mk is always called indirectly, so no need to set .SUFFIXES or
MAKEFLAGS there again.

Differential Revision: https://phabricator.haskell.org/D915

Makefile

@@ -10,6 +10,14 @@
 #
 # -----------------------------------------------------------------------------
 
+# Eliminate use of the built-in implicit rules, and clear out the default list
+# of suffixes for suffix rules. Speeds up make quite a bit. Both are needed
+# for the shortest `make -d` output.
+# Don't set --no-builtin-variables; some rules might stop working if you do
+# (e.g. 'make clean' in testsuite/ currently relies on an implicit $RM).
+MAKEFLAGS += --no-builtin-rules
+.SUFFIXES:
+
 ifeq "$(wildcard distrib/)" ""
 
 # We're in a bindist
@@ -21,7 +29,7 @@ default:
 
 .PHONY: install show
 install show:
-	$(MAKE) -r --no-print-directory -f ghc.mk $@ BINDIST=YES NO_INCLUDE_DEPS=YES
+	$(MAKE) --no-print-directory -f ghc.mk $@ BINDIST=YES NO_INCLUDE_DEPS=YES
 
 else
 
@@ -70,14 +78,14 @@ REALGOALS=$(filter-out binary-dist binary-dist-prep bootstrapping-files framewor
 $(REALGOALS) all: mk/config.mk.old mk/project.mk.old compiler/ghc.cabal.old
 ifneq "$(OMIT_PHASE_0)" "YES"
 	@echo "===--- building phase 0"
-	$(MAKE) -r --no-print-directory -f ghc.mk phase=0 phase_0_builds
+	$(MAKE) --no-print-directory -f ghc.mk phase=0 phase_0_builds
 endif
 ifneq "$(OMIT_PHASE_1)" "YES"
 	@echo "===--- building phase 1"
-	$(MAKE) -r --no-print-directory -f ghc.mk phase=1 phase_1_builds
+	$(MAKE) --no-print-directory -f ghc.mk phase=1 phase_1_builds
 endif
 	@echo "===--- building final phase"
-	$(MAKE) -r --no-print-directory -f ghc.mk phase=final $@
+	$(MAKE) --no-print-directory -f ghc.mk phase=final $@
 
 .PHONY: binary-dist
 binary-dist: binary-dist-prep
@@ -86,25 +94,25 @@ binary-dist: binary-dist-prep
 .PHONY: binary-dist-prep
 binary-dist-prep:
 ifeq "$(mingw32_TARGET_OS)" "1"
-	$(MAKE) -r --no-print-directory -f ghc.mk windows-binary-dist-prep
+	$(MAKE) --no-print-directory -f ghc.mk windows-binary-dist-prep
 else
 	rm -f bindist-list
-	$(MAKE) -r --no-print-directory -f ghc.mk bindist BINDIST=YES
-	$(MAKE) -r --no-print-directory -f ghc.mk unix-binary-dist-prep
+	$(MAKE) --no-print-directory -f ghc.mk bindist BINDIST=YES
+	$(MAKE) --no-print-directory -f ghc.mk unix-binary-dist-prep
 endif
 
 .PHONY: clean distclean maintainer-clean
 clean distclean maintainer-clean:
-	$(MAKE) -r --no-print-directory -f ghc.mk $@ CLEANING=YES
+	$(MAKE) --no-print-directory -f ghc.mk $@ CLEANING=YES
 	test ! -d testsuite || $(MAKE) -C testsuite $@
 
 .PHONY: $(filter clean_%,$(MAKECMDGOALS))
 $(filter clean_%, $(MAKECMDGOALS)) : clean_% :
-	$(MAKE) -r --no-print-directory -f ghc.mk $@ CLEANING=YES
+	$(MAKE) --no-print-directory -f ghc.mk $@ CLEANING=YES
 
 .PHONY: bootstrapping-files show echo
 bootstrapping-files show echo:
-	$(MAKE) -r --no-print-directory -f ghc.mk $@
+	$(MAKE) --no-print-directory -f ghc.mk $@
 
 ifeq "$(darwin_TARGET_OS)" "1"
 .PHONY: framework-pkg

ghc.mk

@@ -107,12 +107,6 @@ nothing=
 space=$(nothing) $(nothing)
 comma=,
 
-# Cancel all suffix rules.  Ideally we'd like to have 'make -r' turned on
-# by default, because that disables all the implicit rules, but there doesn't
-# seem to be a good way to do that.  This turns off all the old-style suffix
-# rules, which does half the job and speeds up make quite a bit:
-.SUFFIXES:
-
 # -----------------------------------------------------------------------------
 # Makefile debugging
 #

mk/sub-makefile.mk

@@ -9,7 +9,12 @@
 #  make clean  ==>  make -C $(TOP) clean_dir
 #
 
-# Important, otherwise we get silly built-in rules:
+# Eliminate use of the built-in implicit rules, and clear out the default list
+# of suffixes for suffix rules. Speeds up make quite a bit. Both are needed
+# for the shortest `make -d` output.
+# Don't set --no-builtin-variables; some rules might stop working if you do
+# (e.g. 'make clean' in testsuite/ currently relies on an implicit $RM).
+MAKEFLAGS += --no-builtin-rules
 .SUFFIXES:
 
 TOPMAKE = $(MAKE) -C $(TOP)

testsuite/mk/boilerplate.mk

+# Eliminate use of the built-in implicit rules, and clear out the default list
+# of suffixes for suffix rules. Speeds up make quite a bit. Both are needed
+# for the shortest `make -d` output.
+# Don't set --no-builtin-variables; some rules might stop working if you do
+# (e.g. 'make clean' in testsuite/ currently relies on an implicit $RM).
+MAKEFLAGS += --no-builtin-rules
+.SUFFIXES:
 
 default: all