From 79698482665dbc0baffab28aa0b7604ea920f92d Mon Sep 17 00:00:00 2001
From: Christian Kampka <christian@kampka.net>
Date: Wed, 25 Nov 2020 20:15:00 +0100
Subject: [PATCH] libfaketime: fix build with clang

The options -Wno-nonnull-compare, -Wno-error=cast-function-type and -Wno-error=format-truncation
are unsupported by clang, letting the build fail.
---
 .../0001-Remove-unsupported-clang-flags.patch | 25 +++++++++++++++++++
 .../libraries/libfaketime/default.nix         |  7 ++++--
 2 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 pkgs/development/libraries/libfaketime/0001-Remove-unsupported-clang-flags.patch

diff --git a/pkgs/development/libraries/libfaketime/0001-Remove-unsupported-clang-flags.patch b/pkgs/development/libraries/libfaketime/0001-Remove-unsupported-clang-flags.patch
new file mode 100644
index 000000000000..84ee18084c29
--- /dev/null
+++ b/pkgs/development/libraries/libfaketime/0001-Remove-unsupported-clang-flags.patch
@@ -0,0 +1,25 @@
+From f974fe07de9e6820bb1de50b31e480296d1d97b7 Mon Sep 17 00:00:00 2001
+From: Christian Kampka <christian@kampka.net>
+Date: Wed, 25 Nov 2020 20:09:50 +0100
+Subject: [PATCH] Remove unsupported clang flags
+
+---
+ src/Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/Makefile b/src/Makefile
+index f13a6bb..b305150 100644
+--- a/src/Makefile
++++ b/src/Makefile
+@@ -69,7 +69,7 @@ PREFIX ?= /usr/local
+ LIBDIRNAME ?= /lib/faketime
+ PLATFORM ?=$(shell uname)
+ 
+-CFLAGS += -std=gnu99 -Wall -Wextra -Werror -Wno-nonnull-compare -DFAKE_PTHREAD -DFAKE_STAT -DFAKE_SLEEP -DFAKE_TIMERS -DFAKE_INTERNAL_CALLS -fPIC -DPREFIX='"'$(PREFIX)'"' -DLIBDIRNAME='"'$(LIBDIRNAME)'"' $(FAKETIME_COMPILE_CFLAGS)
++CFLAGS += -std=gnu99 -Wall -Wextra -DFAKE_PTHREAD -DFAKE_STAT -DFAKE_SLEEP -DFAKE_TIMERS -DFAKE_INTERNAL_CALLS -fPIC -DPREFIX='"'$(PREFIX)'"' -DLIBDIRNAME='"'$(LIBDIRNAME)'"' $(FAKETIME_COMPILE_CFLAGS)
+ ifeq ($(PLATFORM),SunOS)
+ CFLAGS += -D__EXTENSIONS__ -D_XOPEN_SOURCE=600
+ endif
+-- 
+2.28.0
+
diff --git a/pkgs/development/libraries/libfaketime/default.nix b/pkgs/development/libraries/libfaketime/default.nix
index 10cc5cace7b5..6c751e07b831 100644
--- a/pkgs/development/libraries/libfaketime/default.nix
+++ b/pkgs/development/libraries/libfaketime/default.nix
@@ -11,7 +11,10 @@ stdenv.mkDerivation rec {
 
   patches = [
     ./no-date-in-gzip-man-page.patch
-  ];
+  ] ++ (stdenv.lib.optionals stdenv.cc.isClang [
+    # https://github.com/wolfcw/libfaketime/issues/277
+    ./0001-Remove-unsupported-clang-flags.patch
+  ]);
 
   postPatch = ''
     patchShebangs test src
@@ -24,7 +27,7 @@ stdenv.mkDerivation rec {
   PREFIX = placeholder "out";
   LIBDIRNAME = "/lib";
 
-  NIX_CFLAGS_COMPILE = "-Wno-error=cast-function-type -Wno-error=format-truncation";
+  NIX_CFLAGS_COMPILE = stdenv.lib.optionalString stdenv.cc.isClang "-Wno-error=cast-function-type -Wno-error=format-truncation";
 
   checkInputs = [ perl ];