fmt: init at 5.2.1

This commit adds fmt, a C++ formatting library.

pkgs/development/libraries/fmt/default.nix

@@ -0,0 +1,31 @@
+{ stdenv, fetchFromGitHub, cmake, enableShared ? true }:
+
+stdenv.mkDerivation rec {
+  version = "5.2.1";
+  name = "fmt-${version}";
+  src = fetchFromGitHub {
+    owner = "fmtlib";
+    repo = "fmt";
+    rev = "${version}";
+    sha256 = "1cd8yq8va457iir1hlf17ksx11fx2hlb8i4jml8gj1875pizm0pk";
+  };
+  nativeBuildInputs = [ cmake ];
+  doCheck = true;
+  # preCheckHook ensures the test binaries can find libfmt.so.5
+  preCheck = if enableShared
+             then "export LD_LIBRARY_PATH=\"$PWD\""
+             else "";
+  cmakeFlags = [ "-DFMT_TEST=yes"
+                 "-DBUILD_SHARED_LIBS=${if enableShared then "ON" else "OFF"}" ];
+  meta = with stdenv.lib; {
+    homepage = http://fmtlib.net/;
+    description = "Small, safe and fast formatting library";
+    longDescription = ''
+      fmt (formerly cppformat) is an open-source formatting library. It can be
+      used as a fast and safe alternative to printf and IOStreams.
+    '';
+    maintainers = [ maintainers.jdehaas ];
+    license = licenses.bsd2;
+    platforms = platforms.unix;
+  };
+}