From 9ea7693021b2286f07d29ac72761f31a10bef39d Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Sat, 1 Feb 2020 17:57:18 -0500
Subject: [PATCH] makefile: move ghc-options from the cabal file into the
 makefile.

We shouldn't be hard-coding user preferences into the cabal file that
everyone uses. Instead, GHC should support a variable like CFLAGS that
lets users and developers specify what warnings and optimizations
they would like to use. Instead, we have to fake it: I've standardized
the Gentoo HCFLAGS variable within the makefile, so that a few warnings
will be appended to the (exported) environment variable but otherwise
no flags will be forced by the cabal file.

This should work for me when I'm developing, because the warnings will
be appended to the HCFLAGS="-O2" that I have set in my environment. It
will work on Gentoo, because HCFLAGS are already passed to the cabal
build system in Gentoo. It will work(ish) everywhere else, because
nothing will get passed to the cabal build system, and that's okay.
---
 haeredes.cabal | 35 -----------------------------------
 makefile       | 17 ++++++++++++++---
 2 files changed, 14 insertions(+), 38 deletions(-)

diff --git a/haeredes.cabal b/haeredes.cabal
index fac5582..f656773 100644
--- a/haeredes.cabal
+++ b/haeredes.cabal
@@ -86,17 +86,6 @@ executable haeredes
     Paths_haeredes
     Timeout
 
-  ghc-options:
-    -Weverything
-    -Wno-implicit-prelude
-    -Wno-safe
-    -Wno-unsafe
-    -Wno-all-missed-specialisations
-    -rtsopts
-    -threaded
-    -optc-O3
-    -optc-march=native
-
 
 test-suite doctests
   type: exitcode-stdio-1.0
@@ -108,18 +97,6 @@ test-suite doctests
     doctest   >= 0.9,
     filemanip >= 0.3.6
 
-  -- It's not entirely clear to me why I have to reproduce all of this.
-  ghc-options:
-    -Weverything
-    -Wno-implicit-prelude
-    -Wno-safe
-    -Wno-unsafe
-    -Wno-all-missed-specialisations
-    -rtsopts
-    -threaded
-    -optc-O3
-    -optc-march=native
-
 
 -- These won't work without shelltestrunner installed in your
 -- $PATH. Maybe there is some way to tell Cabal that.
@@ -132,18 +109,6 @@ test-suite shelltests
     base                        == 4.*,
     process                     >= 1.1
 
-  -- It's not entirely clear to me why I have to reproduce all of this.
-  ghc-options:
-    -Weverything
-    -Wno-implicit-prelude
-    -Wno-safe
-    -Wno-unsafe
-    -Wno-all-missed-specialisations
-    -rtsopts
-    -threaded
-    -optc-O3
-    -optc-march=native
-
 
 source-repository head
   type: git
diff --git a/makefile b/makefile
index f67f8a5..049fe55 100644
--- a/makefile
+++ b/makefile
@@ -2,11 +2,22 @@ PN            = haeredes
 BIN           = dist/build/$(PN)/$(PN)
 SRCS          = $(shell find src/ -type f -name '*.hs')
 
+# Append these warnings to the HCFLAGS environment variable that gets
+# passed as options to GHC. We want to see the warnings while developing
+# but don't want them hard-coded in the cabal file for end users.
+HCFLAGS += -Weverything \
+           -Wno-implicit-prelude \
+           -Wno-safe \
+           -Wno-unsafe \
+           -Wno-all-missed-specialisations \
+           -rtsopts \
+           -threaded
+
 .PHONY : dist hlint
 
 $(BIN): $(PN).cabal $(SRCS)
 	runghc Setup.hs configure --user
-	runghc Setup.hs build
+	runghc Setup.hs build --ghc-options="${HCFLAGS}"
 
 doc: $(PN).cabal $(SRCS)
 	runghc Setup.hs haddock  --all \
@@ -23,12 +34,12 @@ TEST_SRCS := $(shell find test/ -type f -name '*.hs')
 
 $(TESTSUITE_BIN): $(PN).cabal $(SRCS) $(TEST_SRCS)
 	runghc Setup.hs configure --user --enable-tests --prefix=/
-	runghc Setup.hs build
+	runghc Setup.hs build --ghc-options="${HCFLAGS}"
 
 
 $(DOCTESTS_BIN): $(PN).cabal $(SRCS) $(TEST_SRCS)
 	runghc Setup.hs configure --user --enable-tests
-	runghc Setup.hs build
+	runghc Setup.hs build --ghc-options="${HCFLAGS}"
 
 check: $(BIN) $(TESTSUITE_BIN) $(DOCTESTS_BIN)
 	runghc Setup.hs test
-- 
2.43.2