20 files changed, 57 insertions, 52 deletions
diff --git a/libraries/base/Control/Arrow.hs b/libraries/base/Control/Arrow.hs
index 8a4bc2d22f..3417f30cc1 100644
--- a/libraries/base/Control/Arrow.hs
+++ b/libraries/base/Control/Arrow.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE NoImplicitPrelude #-}
-{-# OPTIONS_GHC -fno-warn-inline-rule-shadowing #-}
+{-# OPTIONS_GHC -Wno-inline-rule-shadowing #-}
     -- The RULES for the methods of class Arrow may never fire
     -- e.g. compose/arr;  see Trac #10528
 
diff --git a/libraries/base/Control/Category.hs b/libraries/base/Control/Category.hs
index 8616a17cdd..b638189b60 100644
--- a/libraries/base/Control/Category.hs
+++ b/libraries/base/Control/Category.hs
@@ -2,7 +2,7 @@
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE PolyKinds #-}
-{-# OPTIONS_GHC -fno-warn-inline-rule-shadowing #-}
+{-# OPTIONS_GHC -Wno-inline-rule-shadowing #-}
     -- The RULES for the methods of class Category may never fire
     -- e.g. identity/left, identity/right, association;  see Trac #10528
 
diff --git a/libraries/base/Control/Concurrent.hs b/libraries/base/Control/Concurrent.hs
index 1786c3ded3..babe8d9a76 100644
--- a/libraries/base/Control/Concurrent.hs
+++ b/libraries/base/Control/Concurrent.hs
@@ -5,7 +5,7 @@
            , ScopedTypeVariables
            , RankNTypes
   #-}
-{-# OPTIONS_GHC -fno-warn-deprecations #-}
+{-# OPTIONS_GHC -Wno-deprecations #-}
 -- kludge for the Control.Concurrent.QSem, Control.Concurrent.QSemN
 -- and Control.Concurrent.SampleVar imports.
 
diff --git a/libraries/base/Foreign/C/Types.hs b/libraries/base/Foreign/C/Types.hs
index cc0eb1b729..fef8e4a3b6 100644
--- a/libraries/base/Foreign/C/Types.hs
+++ b/libraries/base/Foreign/C/Types.hs
@@ -1,8 +1,8 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE CPP, NoImplicitPrelude, MagicHash, GeneralizedNewtypeDeriving,
              StandaloneDeriving #-}
-{-# OPTIONS_GHC -fno-warn-unused-binds #-}
--- XXX -fno-warn-unused-binds stops us warning about unused constructors,
+{-# OPTIONS_GHC -Wno-unused-binds #-}
+-- XXX -Wno-unused-binds stops us warning about unused constructors,
 -- but really we should just remove them if we don't want them
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/Base.hs b/libraries/base/GHC/Base.hs
index 90eaaf0a1e..89ec703163 100644
--- a/libraries/base/GHC/Base.hs
+++ b/libraries/base/GHC/Base.hs
@@ -84,9 +84,9 @@ Other Prelude modules are much easier with fewer complex dependencies.
            , ExistentialQuantification
            , RankNTypes
   #-}
--- -fno-warn-orphans is needed for things like:
+-- -Wno-orphans is needed for things like:
 -- Orphan rule: "x# -# x#" ALWAYS forall x# :: Int# -# x# x# = 0
-{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
 {-# OPTIONS_HADDOCK hide #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/Conc.hs b/libraries/base/GHC/Conc.hs
index 68182a11e4..38fac431b0 100644
--- a/libraries/base/GHC/Conc.hs
+++ b/libraries/base/GHC/Conc.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Unsafe #-}
 {-# LANGUAGE CPP, NoImplicitPrelude #-}
-{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+{-# OPTIONS_GHC -Wno-missing-signatures #-}
 {-# OPTIONS_HADDOCK not-home #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/Conc/IO.hs b/libraries/base/GHC/Conc/IO.hs
index 3a57c93369..b2c96b9fdb 100644
--- a/libraries/base/GHC/Conc/IO.hs
+++ b/libraries/base/GHC/Conc/IO.hs
@@ -4,7 +4,7 @@
            , MagicHash
            , UnboxedTuples
   #-}
-{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+{-# OPTIONS_GHC -Wno-missing-signatures #-}
 {-# OPTIONS_HADDOCK not-home #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/Conc/Sync.hs b/libraries/base/GHC/Conc/Sync.hs
index 83934fe05a..5e277332d0 100644
--- a/libraries/base/GHC/Conc/Sync.hs
+++ b/libraries/base/GHC/Conc/Sync.hs
@@ -8,7 +8,7 @@
            , StandaloneDeriving
            , RankNTypes
   #-}
-{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+{-# OPTIONS_GHC -Wno-missing-signatures #-}
 {-# OPTIONS_HADDOCK not-home #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/Conc/Windows.hs b/libraries/base/GHC/Conc/Windows.hs
index 16112cdd7c..8913a65907 100644
--- a/libraries/base/GHC/Conc/Windows.hs
+++ b/libraries/base/GHC/Conc/Windows.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE CPP, NoImplicitPrelude, MagicHash, UnboxedTuples #-}
-{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+{-# OPTIONS_GHC -Wno-missing-signatures #-}
 {-# OPTIONS_HADDOCK not-home #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/Event/IntTable.hs b/libraries/base/GHC/Event/IntTable.hs
index 8d0f1797c2..ea487d5391 100644
--- a/libraries/base/GHC/Event/IntTable.hs
+++ b/libraries/base/GHC/Event/IntTable.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE BangPatterns, NoImplicitPrelude, RecordWildCards #-}
-{-# OPTIONS_GHC -fno-warn-name-shadowing #-}
+{-# OPTIONS_GHC -Wno-name-shadowing #-}
 
 module GHC.Event.IntTable
     (
diff --git a/libraries/base/GHC/Float.hs b/libraries/base/GHC/Float.hs
index 74d7cb8f01..e6180afcf6 100644
--- a/libraries/base/GHC/Float.hs
+++ b/libraries/base/GHC/Float.hs
@@ -6,7 +6,7 @@
   #-}
 -- We believe we could deorphan this module, by moving lots of things
 -- around, but we haven't got there yet:
-{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
 {-# OPTIONS_HADDOCK hide #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/IO/Encoding/CodePage/API.hs b/libraries/base/GHC/IO/Encoding/CodePage/API.hs
index 7fd22cb012..103eb87a0d 100644
--- a/libraries/base/GHC/IO/Encoding/CodePage/API.hs
+++ b/libraries/base/GHC/IO/Encoding/CodePage/API.hs
@@ -1,7 +1,7 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE CPP, NoImplicitPrelude, NondecreasingIndentation,
              RecordWildCards, ScopedTypeVariables #-}
-{-# OPTIONS_GHC -fno-warn-name-shadowing #-}
+{-# OPTIONS_GHC -Wno-name-shadowing #-}
 
 module GHC.IO.Encoding.CodePage.API (
     mkCodePageEncoding
diff --git a/libraries/base/GHC/IO/FD.hs b/libraries/base/GHC/IO/FD.hs
index edce50003d..eb7b80bb44 100644
--- a/libraries/base/GHC/IO/FD.hs
+++ b/libraries/base/GHC/IO/FD.hs
@@ -3,7 +3,7 @@
            , NoImplicitPrelude
            , BangPatterns
   #-}
-{-# OPTIONS_GHC -fno-warn-identities #-}
+{-# OPTIONS_GHC -Wno-identities #-}
 -- Whether there are identities depends on the platform
 {-# OPTIONS_HADDOCK hide #-}
 
diff --git a/libraries/base/GHC/IO/Handle.hs b/libraries/base/GHC/IO/Handle.hs
index ac37ad45f9..750dbf7a4d 100644
--- a/libraries/base/GHC/IO/Handle.hs
+++ b/libraries/base/GHC/IO/Handle.hs
@@ -4,7 +4,7 @@
            , RecordWildCards
            , NondecreasingIndentation
   #-}
-{-# OPTIONS_GHC -fno-warn-unused-matches #-}
+{-# OPTIONS_GHC -Wno-unused-matches #-}
 
 -----------------------------------------------------------------------------
 -- |
diff --git a/libraries/base/GHC/IO/Handle/Internals.hs b/libraries/base/GHC/IO/Handle/Internals.hs
index 37251abd06..581eb9bbfa 100644
--- a/libraries/base/GHC/IO/Handle/Internals.hs
+++ b/libraries/base/GHC/IO/Handle/Internals.hs
@@ -5,8 +5,8 @@
            , NondecreasingIndentation
            , RankNTypes
   #-}
-{-# OPTIONS_GHC -fno-warn-unused-matches #-}
-{-# OPTIONS_GHC -fno-warn-name-shadowing #-}
+{-# OPTIONS_GHC -Wno-unused-matches #-}
+{-# OPTIONS_GHC -Wno-name-shadowing #-}
 {-# OPTIONS_HADDOCK hide #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/IO/Handle/Text.hs b/libraries/base/GHC/IO/Handle/Text.hs
index 88ec3c4e67..c31ab70a4a 100644
--- a/libraries/base/GHC/IO/Handle/Text.hs
+++ b/libraries/base/GHC/IO/Handle/Text.hs
@@ -6,8 +6,8 @@
            , NondecreasingIndentation
            , MagicHash
   #-}
-{-# OPTIONS_GHC -fno-warn-name-shadowing #-}
-{-# OPTIONS_GHC -fno-warn-unused-matches #-}
+{-# OPTIONS_GHC -Wno-name-shadowing #-}
+{-# OPTIONS_GHC -Wno-unused-matches #-}
 {-# OPTIONS_HADDOCK hide #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/GHC/Real.hs b/libraries/base/GHC/Real.hs
index 71de0d27d7..31381d6bd9 100644
--- a/libraries/base/GHC/Real.hs
+++ b/libraries/base/GHC/Real.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE CPP, NoImplicitPrelude, MagicHash, UnboxedTuples, BangPatterns #-}
-{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
 {-# OPTIONS_HADDOCK hide #-}
 
 -----------------------------------------------------------------------------
diff --git a/libraries/base/Text/Show/Functions.hs b/libraries/base/Text/Show/Functions.hs
index 690b203ea3..5230a4b4ca 100644
--- a/libraries/base/Text/Show/Functions.hs
+++ b/libraries/base/Text/Show/Functions.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE Safe #-}
 -- This module deliberately declares orphan instances:
-{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
 
 -----------------------------------------------------------------------------
 -- |
diff --git a/libraries/ghc-prim/GHC/Classes.hs b/libraries/ghc-prim/GHC/Classes.hs
index 0e74bef07c..19192fb725 100644
--- a/libraries/ghc-prim/GHC/Classes.hs
+++ b/libraries/ghc-prim/GHC/Classes.hs
@@ -7,11 +7,11 @@
 {-# LANGUAGE UndecidableSuperClasses #-}
   -- Because of the type-variable superclasses for tuples
 
-{-# OPTIONS_GHC -fno-warn-unused-imports #-}
--- -fno-warn-unused-imports needed for the GHC.Tuple import below. Sigh.
+{-# OPTIONS_GHC -Wno-unused-imports #-}
+-- -Wno-unused-imports needed for the GHC.Tuple import below. Sigh.
 
-{-# OPTIONS_GHC -fno-warn-unused-top-binds #-}
--- -fno-warn-unused-top-binds is there (I hope) to stop Haddock complaining
+{-# OPTIONS_GHC -Wno-unused-top-binds #-}
+-- -Wno-unused-top-binds is there (I hope) to stop Haddock complaining
 -- about the constraint tuples being defined but not used
 
 {-# OPTIONS_HADDOCK hide #-}
diff --git a/mk/warnings.mk b/mk/warnings.mk
index f8db8fd35d..dd7967383a 100644
--- a/mk/warnings.mk
+++ b/mk/warnings.mk
@@ -32,15 +32,20 @@ SRC_CC_WARNING_OPTS += -Wno-unknown-pragmas
 
 endif
 
-SRC_HC_WARNING_OPTS_STAGE1 += -fwarn-noncanonical-monad-instances
-SRC_HC_WARNING_OPTS_STAGE2 += -fwarn-noncanonical-monad-instances
+SRC_HC_WARNING_OPTS_STAGE1 += -Wnoncanonical-monad-instances
+SRC_HC_WARNING_OPTS_STAGE2 += -Wnoncanonical-monad-instances
 
 
 ######################################################################
 # Disable some warnings in packages we use
 
+# NB: The GHC version used for bootstrapping may not support the
+# `-W`-aliases for `-f(no-)warn` flags introduced in GHC 8.0, so in
+# some cases (watch out for make-variables with a name containing
+# "boot") we need to pass the legacy `-f(no-)warn`-flags instead.
+
 # Libraries that have dubious RULES
-libraries/bytestring_dist-install_EXTRA_HC_OPTS += -fno-warn-inline-rule-shadowing
+libraries/bytestring_dist-install_EXTRA_HC_OPTS += -Wno-inline-rule-shadowing
 
 # Cabal doesn't promise to be warning-free
 utils/ghc-cabal_dist_EXTRA_HC_OPTS += -w
@@ -48,47 +53,47 @@ libraries/Cabal/Cabal_dist-boot_EXTRA_HC_OPTS += -w
 libraries/Cabal/Cabal_dist-install_EXTRA_HC_OPTS += -w
 
 # Turn off import warnings for bad unused imports
-libraries/containers_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
-libraries/bytestring_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
-utils/haddock_dist_EXTRA_HC_OPTS += -fno-warn-unused-imports
-libraries/vector_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
+libraries/containers_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
+libraries/bytestring_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
+utils/haddock_dist_EXTRA_HC_OPTS += -Wno-unused-imports
+libraries/vector_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
 
 # haddock's attoparsec uses deprecated `inlinePerformIO`
-utils/haddock_dist_EXTRA_HC_OPTS += -fno-warn-deprecations
+utils/haddock_dist_EXTRA_HC_OPTS += -Wno-deprecations
 
 # containers uses bitSize at the moment
-libraries/containers_dist-install_EXTRA_HC_OPTS += -fno-warn-deprecations
-libraries/containers_dist-install_EXTRA_HC_OPTS += -fno-warn-redundant-constraints
+libraries/containers_dist-install_EXTRA_HC_OPTS += -Wno-deprecations
+libraries/containers_dist-install_EXTRA_HC_OPTS += -Wno-redundant-constraints
 
 # On Windows, there are also some unused import warnings
 ifeq "$(HostOS_CPP)" "mingw32"
-libraries/time_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports -fno-warn-identities
+libraries/time_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports -Wno-identities
 endif
 
 # haskeline has warnings about deprecated use of block/unblock
-libraries/haskeline_dist-install_EXTRA_HC_OPTS += -fno-warn-deprecations
-libraries/haskeline_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
-libraries/haskeline_dist-install_EXTRA_HC_OPTS += -fno-warn-redundant-constraints
+libraries/haskeline_dist-install_EXTRA_HC_OPTS += -Wno-deprecations
+libraries/haskeline_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
+libraries/haskeline_dist-install_EXTRA_HC_OPTS += -Wno-redundant-constraints
 
 # binary upstream has some warnings, so don't use -Werror for it
 libraries/binary_dist-boot_EXTRA_HC_OPTS += -Wwarn
 libraries/binary_dist-install_EXTRA_HC_OPTS += -Wwarn
 
 # temporarily turn off unused-imports warnings for pretty
-libraries/pretty_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
+libraries/pretty_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
 
 # primitive has a warning about deprecated use of GHC.IOBase
-libraries/primitive_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
+libraries/primitive_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
 
 # temporarily turn off unused-imports warnings for terminfo
 libraries/terminfo_dist-boot_EXTRA_HC_OPTS += -fno-warn-unused-imports
-libraries/terminfo_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
+libraries/terminfo_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
 
 # vector has some unused match warnings
 libraries/vector_dist-install_EXTRA_HC_OPTS += -Wwarn
 
 # temporarily turn off unused-imports warnings for xhtml
-libraries/xhtml_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-imports
+libraries/xhtml_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
 
 libraries/dph/dph-base_dist-install_EXTRA_HC_OPTS += -Wwarn
 libraries/dph/dph-prim-interface_dist-install_EXTRA_HC_OPTS += -Wwarn
@@ -98,16 +103,16 @@ libraries/dph/dph-lifted-common-install_EXTRA_HC_OPTS += -Wwarn
 
 # transformers has unused function parameters warnings
 libraries/transformers_dist-boot_EXTRA_HC_OPTS += -fno-warn-unused-matches -fno-warn-unused-imports
-libraries/transformers_dist-install_EXTRA_HC_OPTS += -fno-warn-unused-matches -fno-warn-unused-imports
-libraries/transformers_dist-install_EXTRA_HC_OPTS += -fno-warn-redundant-constraints
+libraries/transformers_dist-install_EXTRA_HC_OPTS += -Wno-unused-matches -Wno-unused-imports
+libraries/transformers_dist-install_EXTRA_HC_OPTS += -Wno-redundant-constraints
 
 # Turn of trustworthy-safe warning
-libraries/base_dist-install_EXTRA_HC_OPTS += -fno-warn-trustworthy-safe
-libraries/ghc-prim_dist-install_EXTRA_HC_OPTS += -fno-warn-trustworthy-safe
-libraries/Win32_dist-install_EXTRA_HC_OPTS += -fno-warn-trustworthy-safe
+libraries/base_dist-install_EXTRA_HC_OPTS += -Wno-trustworthy-safe
+libraries/ghc-prim_dist-install_EXTRA_HC_OPTS += -Wno-trustworthy-safe
+libraries/Win32_dist-install_EXTRA_HC_OPTS += -Wno-trustworthy-safe
 
-# We need -fno-warn-deprecated-flags to avoid failure with -Werror
-GhcLibExtraHcOpts += -fno-warn-deprecated-flags
+# We need -Wno-deprecated-flags to avoid failure with -Werror
+GhcLibExtraHcOpts += -Wno-deprecated-flags
 GhcBootLibExtraHcOpts += -fno-warn-deprecated-flags
 
 # The warning suppression flag below is a temporary kludge. While working with
@@ -116,7 +121,7 @@ GhcBootLibExtraHcOpts += -fno-warn-deprecated-flags
 # http://ghc.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
 # for details
 #
-GhcLibExtraHcOpts += -fno-warn-tabs
+GhcLibExtraHcOpts += -Wno-tabs
 GhcBootLibExtraHcOpts += -fno-warn-tabs