Revert "threaded by default"

This reverts commit fd8fa1f.

Author: angerman

Makefile

@@ -5,7 +5,7 @@ SHELL := bash
 MAKEFLAGS += --warn-undefined-variables --no-builtin-rules
 
 # Default target
-all: stage2 rts-debug rts-no-threaded rts-debug-no-threaded
+all: stage2 rts-debug rts-threaded rts-debug-threaded
 
 CABAL  ?= cabal
 GHC0   ?= ghc
@@ -114,22 +114,22 @@ rts-debug: _stage2/bin/ghc
 	# cabal still writes the environment files even if we pass --write-ghc-environment-files=never
 	log rm -f ~/.ghc/*/*/default
 
-rts-no-threaded: OUT = $(abspath _stage2)
-rts-no-threaded: GHC = $(abspath _stage1/bin/ghc)
-rts-no-threaded: _stage2/bin/ghc
+rts-threaded: OUT = $(abspath _stage2)
+rts-threaded: GHC = $(abspath _stage2/bin/ghc)
+rts-threaded: _stage2/bin/ghc
 	@$(LIB)
 	log rm -f ~/.ghc/*/*/default
-	log $(CABAL_INSTALL) --write-ghc-environment-files=never --package-db=$(abspath _stage1/lib/package.conf.d) --build-package-db=$(abspath _stage0/lib/package.conf.d) --project-file cabal.project.stage2 --lib rts:rts --constraint='rts -threaded'
+	log $(CABAL_INSTALL) --write-ghc-environment-files=never --package-db=$(abspath _stage1/lib/package.conf.d) --build-package-db=$(abspath _stage0/lib/package.conf.d) --project-file cabal.project.stage2 --lib rts:rts --constraint="rts+threaded"
 	# cabal still writes the environment files even if we pass --write-ghc-environment-files=never
 	log rm -f ~/.ghc/*/*/default
 
 
-rts-debug-no-threaded: OUT = $(abspath _stage2)
-rts-debug-no-threaded: GHC = $(abspath _stage1/bin/ghc)
-rts-debug-no-threaded: _stage2/bin/ghc
+rts-debug-threaded: OUT = $(abspath _stage2)
+rts-debug-threaded: GHC = $(abspath _stage2/bin/ghc)
+rts-debug-threaded: _stage2/bin/ghc
 	@$(LIB)
 	log rm -f ~/.ghc/*/*/default
-	log $(CABAL_INSTALL) --write-ghc-environment-files=never --package-db=$(abspath _stage1/lib/package.conf.d) --build-package-db=$(abspath _stage0/lib/package.conf.d) --project-file cabal.project.stage2 --lib rts:rts --constraint='rts +debug -threaded'
+	log $(CABAL_INSTALL) --write-ghc-environment-files=never --package-db=$(abspath _stage1/lib/package.conf.d) --build-package-db=$(abspath _stage0/lib/package.conf.d) --project-file cabal.project.stage2 --lib rts:rts --constraint="rts+debug" --constraint="rts+threaded"
 	# cabal still writes the environment files even if we pass --write-ghc-environment-files=never
 	log rm -f ~/.ghc/*/*/default
 

cabal.project.stage2

@@ -106,7 +106,8 @@ package ghc-internal
   flags: +bignum-native
 
 package ghc-bin
-  flags: +internal-interpreter
+  -- FIXME: we don't have the threaded RTS yet.
+  flags: -threaded +internal-interpreter
 
 package text
   -- FIXME: avoid having to deal with system-cxx-std-lib fake package for now

compiler/GHC/Driver/DynFlags.hs

@@ -636,8 +636,7 @@ defaultDynFlags mySettings =
         ignorePackageFlags      = [],
         trustFlags              = [],
         packageEnv              = Nothing,
-        -- we default to threaded!
-        targetWays_             = Set.singleton WayThreaded,
+        targetWays_             = Set.empty,
         splitInfo               = Nothing,
 
         ghcNameVersion = sGhcNameVersion mySettings,

rts/rts.cabal

@@ -315,7 +315,7 @@ flag dynamic
   default: False
   manual: True
 flag threaded
-  default: True
+  default: False
   manual: True
 flag thread-sanitizer
   description: