From 15014bcec5072c1bbb4b1d46a75f44b97c852f83 Mon Sep 17 00:00:00 2001
From: Matthew Pickering <matthewtpickering@gmail.com>
Date: Wed, 7 Dec 2022 10:33:11 +0000
Subject: compiler: Add -f[no-]split-sections flags

Here we add a `-fsplit-sections` flag which may some day replace
`-split-sections`. This has the advantage of automatically providing a
`-fno-split-sections` flag, which is useful for our packaging because we
enable `-split-sections` by default but want to disable it in certain
configurations.

(cherry picked from commit 32255d055b768d51deb9d1f49681164cf7492011)
---
 compiler/GHC/Driver/Session.hs | 20 ++++++++++++--------
 docs/users_guide/phases.rst    |  4 +++-
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index 831267e2bf..07106c7c8c 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -2192,14 +2192,10 @@ dynamic_flags_deps = [
   , make_ord_flag defGhcFlag "split-objs"
       (NoArg $ addWarn "ignoring -split-objs")
 
+    -- N.B. We may someday deprecate this in favor of -fsplit-sections,
+    -- which has the benefit of also having a negating -fno-split-sections.
   , make_ord_flag defGhcFlag "split-sections"
-      (noArgM (\dflags -> do
-        if platformHasSubsectionsViaSymbols (targetPlatform dflags)
-          then do addWarn $
-                    "-split-sections is not useful on this platform " ++
-                    "since it always uses subsections via symbols. Ignoring."
-                  return dflags
-          else return (gopt_set dflags Opt_SplitSections)))
+      (NoArg $ setGeneralFlag Opt_SplitSections)
 
         -------- ghc -M -----------------------------------------------------
   , make_ord_flag defGhcFlag "dep-suffix"              (hasArg addDepSuffix)
@@ -3514,7 +3510,8 @@ fFlagsDeps = [
                (addWarn "-compact-unwind is only implemented by the darwin platform. Ignoring.")
         return dflags)),
   flagSpec "show-error-context"               Opt_ShowErrorContext,
-  flagSpec "cmm-thread-sanitizer"             Opt_CmmThreadSanitizer
+  flagSpec "cmm-thread-sanitizer"             Opt_CmmThreadSanitizer,
+  flagSpec "split-sections"                   Opt_SplitSections
   ]
   ++ fHoleFlags
 
@@ -4800,6 +4797,13 @@ makeDynFlagsConsistent dflags
           warn = "-dynamic-too is ignored when using -dynamic"
       in loop dflags' warn
 
+ | gopt Opt_SplitSections dflags
+ , platformHasSubsectionsViaSymbols (targetPlatform dflags)
+    = let dflags' = gopt_unuset dflags Opt_SplitSections
+          warn = "-fsplit-sections is not useful on this platform " ++
+                 "since it uses subsections-via-symbols. Ignoring."
+      in loop dflags' warn
+
    -- Via-C backend only supports unregisterised ABI. Switch to a backend
    -- supporting it if possible.
  | backendUnregisterisedAbiOnly (backend dflags) &&
diff --git a/docs/users_guide/phases.rst b/docs/users_guide/phases.rst
index aa171c2055..8d0c32f5c1 100644
--- a/docs/users_guide/phases.rst
+++ b/docs/users_guide/phases.rst
@@ -909,10 +909,12 @@ for example).
     option for Apple's Linker (``-F`` already means something else for
     GHC).
 
-.. ghc-flag:: -split-sections
+.. ghc-flag:: -fsplit-sections
+              -split-sections
     :shortdesc: Split sections for link-time dead-code stripping
     :type: dynamic
     :category: linking
+    :reverse: -fno-split-sections
 
     Place each generated function or data item into its own section in the
     output file if the target supports arbitrary sections. The name of the
-- 
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