ghc: don’t add libiconv automatically

ghc needs it to fail to correctly detect it for later.

doc/stdenv.xml

@@ -2525,6 +2525,23 @@ addEnvHooks "$hostOffset" myBashFunction
       </para>
      </listitem>
     </varlistentry>
+    <varlistentry>
+     <term>
+      libiconv, libintl
+     </term>
+     <listitem>
+       <para>
+	 A few libraries automatically add to
+	 <literal>NIX_LDFLAGS</literal> their library, making their
+	 symbols automatically available to the linker. This includes
+	 libiconv and libintl (gettext). This is done to provide
+	 compatibility between GNU Linux, where libiconv and libintl
+	 are bundled in, and other systems where that might not be the
+	 case. Sometimes, this behavior is not desired. To disable
+	 this behavior, set <literal>dontAddExtraLibs</literal>.
+       </para>
+     </listitem>
+    </varlistentry>
     <varlistentry>
      <term>
       cmake

pkgs/development/compilers/ghc/8.2.2.nix

@@ -206,6 +206,9 @@ stdenv.mkDerivation (rec {
     "--disable-large-address-space"
   ];
 
+  # Don’t add -liconv to LDFLAGS automatically so that GHC will add it itself.
+  dontAddExtraLibs = true;
+
   # Make sure we never relax`$PATH` and hooks support for compatability.
   strictDeps = true;
 

pkgs/development/compilers/ghc/8.4.4.nix

@@ -186,6 +186,9 @@ stdenv.mkDerivation (rec {
   # Make sure we never relax`$PATH` and hooks support for compatability.
   strictDeps = true;
 
+  # Don’t add -liconv to LDFLAGS automatically so that GHC will add it itself.
+  dontAddExtraLibs = true;
+
   nativeBuildInputs = [
     perl autoconf automake m4 python3 sphinx
     ghc bootPkgs.alex bootPkgs.happy bootPkgs.hscolour

pkgs/development/compilers/ghc/8.6.1.nix

@@ -167,6 +167,9 @@ stdenv.mkDerivation (rec {
   # Make sure we never relax`$PATH` and hooks support for compatability.
   strictDeps = true;
 
+  # Don’t add -liconv to LDFLAGS automatically so that GHC will add it itself.
+  dontAddExtraLibs = true;
+
   nativeBuildInputs = [
     perl autoconf automake m4 python3 sphinx
     ghc bootPkgs.alex bootPkgs.happy bootPkgs.hscolour

pkgs/development/compilers/ghc/8.6.2.nix

@@ -167,6 +167,9 @@ stdenv.mkDerivation (rec {
   # Make sure we never relax`$PATH` and hooks support for compatability.
   strictDeps = true;
 
+  # Don’t add -liconv to LDFLAGS automatically so that GHC will add it itself.
+  dontAddExtraLibs = true;
+
   nativeBuildInputs = [
     perl autoconf automake m4 python3 sphinx
     ghc bootPkgs.alex bootPkgs.happy bootPkgs.hscolour

pkgs/development/compilers/ghc/head.nix

@@ -149,6 +149,9 @@ stdenv.mkDerivation (rec {
   # Make sure we never relax`$PATH` and hooks support for compatability.
   strictDeps = true;
 
+  # Don’t add -liconv to LDFLAGS automatically so that GHC will add it itself.
+  dontAddExtraLibs = true;
+
   nativeBuildInputs = [
     perl autoconf automake m4 python3
     ghc bootPkgs.alex bootPkgs.happy bootPkgs.hscolour

pkgs/development/libraries/gettext/gettext-setup-hook.sh

@@ -10,7 +10,7 @@ addEnvHooks "$hostOffset" gettextDataDirsHook
 
 # libintl must be listed in load flags on non-Glibc
 # it doesn't hurt to have it in Glibc either though
-if [ ! -z "@gettextNeedsLdflags@" ]; then
+if [ -n "@gettextNeedsLdflags@" -a -z "$dontAddExtraLibs" ]; then
     # See pkgs/build-support/setup-hooks/role.bash
     getHostRole
     export NIX_${role_pre}LDFLAGS+=" -lintl"

pkgs/development/libraries/libiconv/setup-hook.sh

@@ -2,5 +2,7 @@
 # it doesn't hurt to have it in Glibc either though
 
 # See pkgs/build-support/setup-hooks/role.bash
+if [ -z "$dontAddExtraLibs" ]; then
     getHostRole
     export NIX_${role_pre}LDFLAGS+=" -liconv"
+fi