treewide: use optionalString

nixos/tests/predictable-interface-names.nix

@@ -13,7 +13,7 @@ in pkgs.lib.listToAttrs (builtins.map ({ predictable, withNetworkd }: {
   name = pkgs.lib.optionalString (!predictable) "un" + "predictable"
        + pkgs.lib.optionalString withNetworkd "Networkd";
   value = makeTest {
-    name = "${if predictable then "" else "un"}predictableInterfaceNames${if withNetworkd then "-with-networkd" else ""}";
+    name = "${lib.optionalString (!predictable) "un"}predictableInterfaceNames${lib.optionalString withNetworkd "-with-networkd"}";
     meta = {};
 
     nodes.machine = { lib, ... }: {

pkgs/applications/audio/espeak/default.nix

@@ -19,9 +19,9 @@ stdenv.mkDerivation rec {
   prePatch = ''
     sed -e s,/bin/ln,ln,g -i src/Makefile
     sed -e 's,^CXXFLAGS=-O2,CXXFLAGS=-O2 -D PATH_ESPEAK_DATA=\\\"$(DATADIR)\\\",' -i src/Makefile
-  '' + (if portaudio.api_version == 19 then ''
+  '' + (lib.optionalString (portaudio.api_version == 19) ''
     cp src/portaudio19.h src/portaudio.h
-  '' else "");
+  '');
 
   configurePhase = ''
     cd src

pkgs/applications/audio/musly/default.nix

@@ -10,11 +10,11 @@ stdenv.mkDerivation {
   };
   nativeBuildInputs = [ cmake ];
   buildInputs = [ eigen ffmpeg ];
-  fixupPhase = if stdenv.isDarwin then ''
+  fixupPhase = lib.optionalString stdenv.isDarwin ''
     install_name_tool -change libmusly.dylib $out/lib/libmusly.dylib $out/bin/musly
     install_name_tool -change libmusly_resample.dylib $out/lib/libmusly_resample.dylib $out/bin/musly
     install_name_tool -change libmusly_resample.dylib $out/lib/libmusly_resample.dylib $out/lib/libmusly.dylib
-  '' else "";
+  '';
 
   meta = with lib; {
     homepage = "https://www.musly.org";

pkgs/applications/display-managers/lightdm-tiny-greeter/default.nix

@@ -15,9 +15,9 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ pkg-config wrapGAppsHook ];
   buildInputs = [ lightdm gtk3 glib ];
 
-  postUnpack = if conf != "" then ''
+  postUnpack = lib.optionalString (conf != "") ''
     cp ${builtins.toFile "config.h" conf} source/config.h
-  '' else "";
+  '';
 
   buildPhase = ''
     mkdir -p $out/bin $out/share/xgreeters

pkgs/applications/editors/texmacs/common.nix

@@ -27,18 +27,18 @@ rec {
 
   postPatch = (if tex == null then ''
     gunzip < ${fullFontsSrc} | (cd TeXmacs && tar xvf -)
-   '' else if extraFonts then ''
+   '' else lib.optionalString extraFonts ''
     gunzip < ${extraFontsSrc} | (cd TeXmacs && tar xvf -)
-   '' else "") +
-   (if chineseFonts then ''
+   '') +
+   (lib.optionalString chineseFonts ''
     gunzip < ${chineseFontsSrc} | (cd TeXmacs && tar xvf -)
-   '' else "") +
-   (if japaneseFonts then ''
+   '') +
+   (lib.optionalString japaneseFonts ''
     gunzip < ${japaneseFontsSrc} | (cd TeXmacs && tar xvf -)
-   '' else "") +
-   (if koreanFonts then ''
+   '') +
+   (lib.optionalString koreanFonts ''
     gunzip < ${koreanFontsSrc} | (cd TeXmacs && tar xvf -)
-   '' else "");
+   '');
 
 
   meta = {

pkgs/applications/editors/vim/plugins/vim-utils.nix

@@ -317,8 +317,8 @@ rec {
       lib.warnIf (wrapManual != null) ''
         vim.customize: wrapManual is deprecated: the manual is now included by default if `name == "vim"`.
         ${if wrapManual == true && name != "vim" then "Set `standalone = false` to include the manual."
-        else if wrapManual == false && name == "vim" then "Set `standalone = true` to get the *vim wrappers only."
-        else ""}''
+        else lib.optionalString (wrapManual == false && name == "vim") "Set `standalone = true` to get the *vim wrappers only."
+        }''
       lib.warnIf (wrapGui != null)
         "vim.customize: wrapGui is deprecated: gvim is now automatically included if present"
       lib.throwIfNot (vimExecutableName == null && gvimExecutableName == null)
@@ -330,7 +330,7 @@ rec {
           else throw "at least one of vimrcConfig and vimrcFile must be specified";
         bin = runCommand "${name}-bin" { nativeBuildInputs = [ makeWrapper ]; } ''
           vimrc=${lib.escapeShellArg vimrc}
-          gvimrc=${if gvimrcFile != null then lib.escapeShellArg gvimrcFile else ""}
+          gvimrc=${lib.optionalString (gvimrcFile != null) (lib.escapeShellArg gvimrcFile)}
 
           mkdir -p "$out/bin"
           for exe in ${

pkgs/applications/file-managers/vifm/default.nix

@@ -34,11 +34,11 @@ in stdenv.mkDerivation rec {
 
     wrapVifmMedia = "wrapProgram $out/share/vifm/vifm-media --prefix PATH : ${path}";
   in ''
-    ${if mediaSupport then wrapVifmMedia else ""}
+    ${lib.optionalString mediaSupport wrapVifmMedia}
   '';
 
   meta = with lib; {
-    description = "A vi-like file manager${if isFullPackage then "; Includes support for optional features" else ""}";
+    description = "A vi-like file manager${lib.optionalString isFullPackage "; Includes support for optional features"}";
     maintainers = with maintainers; [ raskin ];
     platforms = if mediaSupport then platforms.linux else platforms.unix;
     license = licenses.gpl2;

pkgs/applications/misc/blender/default.nix

@@ -87,10 +87,10 @@ stdenv.mkDerivation rec {
     '' else ''
       substituteInPlace extern/clew/src/clew.c --replace '"libOpenCL.so"' '"${ocl-icd}/lib/libOpenCL.so"'
     '') +
-    (if hipSupport then ''
+    (lib.optionalString hipSupport ''
       substituteInPlace extern/hipew/src/hipew.c --replace '"/opt/rocm/hip/lib/libamdhip64.so"' '"${hip}/lib/libamdhip64.so"'
       substituteInPlace extern/hipew/src/hipew.c --replace '"opt/rocm/hip/bin"' '"${hip}/bin"'
-    '' else "");
+    '');
 
   cmakeFlags =
     [

pkgs/applications/networking/browsers/firefox-bin/update.nix

@@ -46,7 +46,7 @@ in writeScript "update-${pname}" ''
            grep "^[0-9]" | \
            sort --version-sort | \
            grep -v "funnelcake" | \
-           grep -e "${if isBeta then "b" else ""}\([[:digit:]]\|[[:digit:]][[:digit:]]\)$" | ${if isBeta then "" else "grep -v \"b\" |"} \
+           grep -e "${lib.optionalString isBeta "b"}\([[:digit:]]\|[[:digit:]][[:digit:]]\)$" | ${lib.optionalString (not isBeta) "grep -v \"b\" |"} \
            tail -1`
 
   curl --silent -o $HOME/shasums "$url$version/SHA256SUMS"

pkgs/applications/networking/browsers/google-chrome/default.nix

@@ -70,7 +70,7 @@ let
     ++ lib.optional libvaSupport libva
     ++ [ gtk3 ];
 
-  suffix = if channel != "stable" then "-" + channel else "";
+  suffix = lib.optionalString (channel != "stable") "-${channel}";
 
   crashpadHandlerBinary = if lib.versionAtLeast version "94"
     then "chrome_crashpad_handler"

pkgs/applications/science/biology/plink-ng/default.nix

@@ -15,7 +15,7 @@ stdenv.mkDerivation rec {
 
   preBuild = ''
     sed -i 's|zlib-1.2.8/zlib.h|zlib.h|g' *.c *.h
-    ${if stdenv.cc.isClang then "sed -i 's|g++|clang++|g' Makefile.std" else ""}
+    ${lib.optionalString stdenv.cc.isClang "sed -i 's|g++|clang++|g' Makefile.std"}
 
     makeFlagsArray+=(
       ZLIB=-lz

pkgs/applications/science/electronics/kicad/base.nix

@@ -76,11 +76,10 @@ stdenv.mkDerivation rec {
   # tagged releases don't have "unknown"
   # kicad nightlies use git describe --dirty
   # nix removes .git, so its approximated here
-  postPatch = if (!stable) then ''
+  postPatch = lib.optionalString (!stable) ''
     substituteInPlace cmake/KiCadVersion.cmake \
       --replace "unknown" "${builtins.substring 0 10 src.rev}"
-  ''
-  else "";
+  '';
 
   makeFlags = optionals (debug) [ "CFLAGS+=-Og" "CFLAGS+=-ggdb" ];
 

pkgs/applications/science/electronics/kicad/default.nix

@@ -214,7 +214,7 @@ stdenv.mkDerivation rec {
     description = (if (stable)
     then "Open Source Electronics Design Automation suite"
     else "Open Source EDA suite, development build")
-    + (if (!with3d) then ", without 3D models" else "");
+    + (lib.optionalString (!with3d) ", without 3D models");
     homepage = "https://www.kicad.org/";
     longDescription = ''
       KiCad is an open source software suite for Electronic Design Automation.

pkgs/applications/science/logic/coq/default.nix

@@ -66,10 +66,10 @@ let
   buildIde = args.buildIde or (!coqAtLeast "8.14");
   ideFlags = optionalString (buildIde && !coqAtLeast "8.10")
     "-lablgtkdir ${ocamlPackages.lablgtk}/lib/ocaml/*/site-lib/lablgtk2 -coqide opt";
-  csdpPatch = if csdp != null then ''
+  csdpPatch = lib.optionalString (csdp != null) ''
     substituteInPlace plugins/micromega/sos.ml --replace "; csdp" "; ${csdp}/bin/csdp"
     substituteInPlace plugins/micromega/coq_micromega.ml --replace "System.is_in_system_path \"csdp\"" "true"
-  '' else "";
+  '';
   ocamlPackages = if !isNull customOCamlPackages then customOCamlPackages
     else with versions; switch coq-version [
       { case = range "8.16" "8.17"; out = ocamlPackages_4_14; }
@@ -158,7 +158,7 @@ self = stdenv.mkDerivation {
     UNAME=$(type -tp uname)
     RM=$(type -tp rm)
     substituteInPlace tools/beautify-archive --replace "/bin/rm" "$RM"
-    ${if !coqAtLeast "8.7" then "substituteInPlace configure.ml --replace \"md5 -q\" \"md5sum\"" else ""}
+    ${lib.optionalString (!coqAtLeast "8.7") "substituteInPlace configure.ml --replace \"md5 -q\" \"md5sum\""}
     ${csdpPatch}
   '';
 
@@ -196,7 +196,7 @@ self = stdenv.mkDerivation {
     categories = [ "Development" "Science" "Math" "IDE" "GTK" ];
   });
 
-  postInstall = let suffix = if coqAtLeast "8.14" then "-core" else ""; in optionalString (!coqAtLeast "8.17") ''
+  postInstall = let suffix = optionalString (coqAtLeast "8.14") "-core"; in optionalString (!coqAtLeast "8.17") ''
     cp bin/votour $out/bin/
   '' + ''
     ln -s $out/lib/coq${suffix} $OCAMLFIND_DESTDIR/coq${suffix}
@@ -227,12 +227,12 @@ if coqAtLeast "8.17" then self.overrideAttrs(_: {
   buildPhase = ''
     runHook preBuild
     make dunestrap
-    dune build -p coq-core,coq-stdlib,coq,coqide-server${if buildIde then ",coqide" else ""} -j $NIX_BUILD_CORES
+    dune build -p coq-core,coq-stdlib,coq,coqide-server${lib.optionalString buildIde ",coqide"} -j $NIX_BUILD_CORES
     runHook postBuild
   '';
   installPhase = ''
     runHook preInstall
-    dune install --prefix $out coq-core coq-stdlib coq coqide-server${if buildIde then " coqide" else ""}
+    dune install --prefix $out coq-core coq-stdlib coq coqide-server${lib.optionalString buildIde " coqide"}
     runHook postInstall
   '';
 }) else self

pkgs/applications/science/math/sage/sage-tests.nix

@@ -18,7 +18,7 @@ let
   src = sage-with-env.env.lib.src;
   runAllTests = files == null;
   testArgs = if runAllTests then "--all" else testFileList;
-  patienceSpecifier = if longTests then "--long" else "";
+  patienceSpecifier = lib.optionalString longTests "--long";
   timeSpecifier = if timeLimit == null then "" else "--short ${toString timeLimit}";
   relpathToArg = relpath: lib.escapeShellArg "${src}/${relpath}"; # paths need to be absolute
   testFileList = lib.concatStringsSep " " (map relpathToArg files);

pkgs/applications/science/misc/openmodelica/mkderivation/default.nix

@@ -16,7 +16,7 @@ let
   # getAttr-like helper for optional append to string:
   # "Hello" + appendByAttr "a" " " {a = "world";} = "Hello world"
   # "Hello" + appendByAttr "a" " " {} = "Hello"
-  appendByAttr = attr: sep: x: if hasAttr attr x then sep + (getAttr attr x) else "";
+  appendByAttr = attr: sep: x: lib.optionalString (hasAttr attr x) (sep + (getAttr attr x));
 
   # Are there any OM dependencies at all?
   ifDeps = length pkg.omdeps != 0;

pkgs/applications/window-managers/dwl/default.nix

@@ -63,8 +63,8 @@ stdenv.mkDerivation (self: {
 
   preBuild = ''
     makeFlagsArray+=(
-      XWAYLAND=${if enableXWayland then "-DXWAYLAND" else ""}
-      XLIBS=${if enableXWayland then "xcb\\ xcb-icccm" else ""}
+      XWAYLAND=${lib.optionalString enableXWayland "-DXWAYLAND"}
+      XLIBS=${lib.optionalString enableXWayland "xcb\\ xcb-icccm"}
     )
   '';
 

pkgs/build-support/alternatives/blas/default.nix

@@ -83,12 +83,12 @@ stdenv.mkDerivation {
 '' + (if stdenv.hostPlatform.parsed.kernel.execFormat.name == "elf" then ''
   patchelf --set-soname libblas${canonicalExtension} $out/lib/libblas${canonicalExtension}
   patchelf --set-rpath "$(patchelf --print-rpath $out/lib/libblas${canonicalExtension}):${lib.getLib blasProvider'}/lib" $out/lib/libblas${canonicalExtension}
-'' else if stdenv.hostPlatform.isDarwin then ''
+'' else lib.optionalString (stdenv.hostPlatform.isDarwin) ''
   install_name_tool \
     -id $out/lib/libblas${canonicalExtension} \
     -add_rpath ${lib.getLib blasProvider'}/lib \
     $out/lib/libblas${canonicalExtension}
-'' else "") + ''
+'') + ''
 
   if [ "$out/lib/libblas${canonicalExtension}" != "$out/lib/libblas${stdenv.hostPlatform.extensions.sharedLibrary}" ]; then
     ln -s $out/lib/libblas${canonicalExtension} "$out/lib/libblas${stdenv.hostPlatform.extensions.sharedLibrary}"
@@ -115,12 +115,12 @@ EOF
 '' + (if stdenv.hostPlatform.parsed.kernel.execFormat.name == "elf" then ''
   patchelf --set-soname libcblas${canonicalExtension} $out/lib/libcblas${canonicalExtension}
   patchelf --set-rpath "$(patchelf --print-rpath $out/lib/libcblas${canonicalExtension}):${lib.getLib blasProvider'}/lib" $out/lib/libcblas${canonicalExtension}
-'' else if stdenv.hostPlatform.isDarwin then ''
+'' else lib.optionalString stdenv.hostPlatform.isDarwin ''
   install_name_tool \
     -id $out/lib/libcblas${canonicalExtension} \
     -add_rpath ${lib.getLib blasProvider'}/lib \
     $out/lib/libcblas${canonicalExtension}
-'' else "") + ''
+'') + ''
   if [ "$out/lib/libcblas${canonicalExtension}" != "$out/lib/libcblas${stdenv.hostPlatform.extensions.sharedLibrary}" ]; then
     ln -s $out/lib/libcblas${canonicalExtension} "$out/lib/libcblas${stdenv.hostPlatform.extensions.sharedLibrary}"
   fi

pkgs/build-support/alternatives/lapack/default.nix

@@ -54,10 +54,10 @@ stdenv.mkDerivation {
   cp -L "$liblapack" $out/lib/liblapack${canonicalExtension}
   chmod +w $out/lib/liblapack${canonicalExtension}
 
-'' + (if stdenv.hostPlatform.parsed.kernel.execFormat.name == "elf" then ''
+'' + (lib.optionalString (stdenv.hostPlatform.parsed.kernel.execFormat.name == "elf") ''
   patchelf --set-soname liblapack${canonicalExtension} $out/lib/liblapack${canonicalExtension}
   patchelf --set-rpath "$(patchelf --print-rpath $out/lib/liblapack${canonicalExtension}):${lapackProvider'}/lib" $out/lib/liblapack${canonicalExtension}
-'' else "") + ''
+'') + ''
 
   if [ "$out/lib/liblapack${canonicalExtension}" != "$out/lib/liblapack${stdenv.hostPlatform.extensions.sharedLibrary}" ]; then
     ln -s $out/lib/liblapack${canonicalExtension} "$out/lib/liblapack${stdenv.hostPlatform.extensions.sharedLibrary}"
@@ -83,10 +83,10 @@ EOF
   cp -L "$liblapacke" $out/lib/liblapacke${canonicalExtension}
   chmod +w $out/lib/liblapacke${canonicalExtension}
 
-'' + (if stdenv.hostPlatform.parsed.kernel.execFormat.name == "elf" then ''
+'' + (lib.optionalString (stdenv.hostPlatform.parsed.kernel.execFormat.name == "elf") ''
   patchelf --set-soname liblapacke${canonicalExtension} $out/lib/liblapacke${canonicalExtension}
   patchelf --set-rpath "$(patchelf --print-rpath $out/lib/liblapacke${canonicalExtension}):${lib.getLib lapackProvider'}/lib" $out/lib/liblapacke${canonicalExtension}
-'' else "") + ''
+'') + ''
 
   if [ -f "$out/lib/liblapacke.so.3" ]; then
     ln -s $out/lib/liblapacke.so.3 $out/lib/liblapacke.so

pkgs/build-support/bintools-wrapper/default.nix

@@ -92,9 +92,8 @@ let
     else "";
 
   expand-response-params =
-    if buildPackages ? stdenv && buildPackages.stdenv.hasCC && buildPackages.stdenv.cc != "/dev/null"
-    then import ../expand-response-params { inherit (buildPackages) stdenv; }
-    else "";
+    lib.optionalString (buildPackages ? stdenv && buildPackages.stdenv.hasCC && buildPackages.stdenv.cc != "/dev/null")
+    (import ../expand-response-params { inherit (buildPackages) stdenv; });
 
 in
 

pkgs/build-support/build-bazel-package/default.nix

@@ -118,10 +118,10 @@ stdenv.mkDerivation (fBuildAttrs // {
 
       # Remove all built in external workspaces, Bazel will recreate them when building
       rm -rf $bazelOut/external/{bazel_tools,\@bazel_tools.marker}
-      ${if removeRulesCC then "rm -rf $bazelOut/external/{rules_cc,\\@rules_cc.marker}" else ""}
+      ${lib.optionalString removeRulesCC "rm -rf $bazelOut/external/{rules_cc,\\@rules_cc.marker}"}
       rm -rf $bazelOut/external/{embedded_jdk,\@embedded_jdk.marker}
-      ${if removeLocalConfigCc then "rm -rf $bazelOut/external/{local_config_cc,\\@local_config_cc.marker}" else ""}
-      ${if removeLocal then "rm -rf $bazelOut/external/{local_*,\\@local_*.marker}" else ""}
+      ${lib.optionalString removeLocalConfigCc "rm -rf $bazelOut/external/{local_config_cc,\\@local_config_cc.marker}"}
+      ${lib.optionalString removeLocal "rm -rf $bazelOut/external/{local_*,\\@local_*.marker}"}
 
       # Clear markers
       find $bazelOut/external -name '@*\.marker' -exec sh -c 'echo > {}' \;

pkgs/build-support/build-fhs-userenv-bubblewrap/env.nix

@@ -212,7 +212,7 @@ in stdenv.mkDerivation {
     cd $out
     ${extraBuildCommands}
     cd $out
-    ${if isMultiBuild then extraBuildCommandsMulti else ""}
+    ${lib.optionalString isMultiBuild extraBuildCommandsMulti}
   '';
   preferLocalBuild = true;
   allowSubstitutes = false;

pkgs/build-support/build-fhs-userenv/env.nix

@@ -1,4 +1,4 @@
-{ stdenv, buildEnv, writeText, pkgs, pkgsi686Linux }:
+{ stdenv, lib, buildEnv, writeText, pkgs, pkgsi686Linux }:
 
 { name
 , profile ? ""
@@ -237,7 +237,7 @@ in stdenv.mkDerivation {
     cd $out
     ${extraBuildCommands}
     cd $out
-    ${if isMultiBuild then extraBuildCommandsMulti else ""}
+    ${lib.optionalString isMultiBuild extraBuildCommandsMulti}
   '';
   preferLocalBuild = true;
   allowSubstitutes = false;

pkgs/build-support/cc-wrapper/default.nix

@@ -59,9 +59,7 @@ let
   suffixSalt = replaceStrings ["-" "."] ["_" "_"] targetPlatform.config;
 
   expand-response-params =
-    if (buildPackages.stdenv.hasCC or false) && buildPackages.stdenv.cc != "/dev/null"
-    then import ../expand-response-params { inherit (buildPackages) stdenv; }
-    else "";
+    lib.optionalString ((buildPackages.stdenv.hasCC or false) && buildPackages.stdenv.cc != "/dev/null") (import ../expand-response-params { inherit (buildPackages) stdenv; });
 
   useGccForLibs = isClang
     && libcxx == null

pkgs/build-support/fetchdocker/credentials.nix

@@ -35,4 +35,4 @@ let
     ({prefix, path}: "DOCKER_CREDENTIALS" == prefix)
     builtins.nixPath);
 in
-  if (pathParts != []) then (builtins.head pathParts).path else ""
+  lib.optionalString (pathParts != []) ((builtins.head pathParts).path)

pkgs/build-support/fetchfossil/default.nix

@@ -1,9 +1,9 @@
-{stdenv, fossil, cacert}:
+{stdenv, lib, fossil, cacert}:
 
 {name ? null, url, rev, sha256}:
 
 stdenv.mkDerivation {
-  name = "fossil-archive" + (if name != null then "-${name}" else "");
+  name = "fossil-archive" + (lib.optionalString (name != null) "-${name}");
   builder = ./builder.sh;
   nativeBuildInputs = [fossil cacert];
 

pkgs/build-support/fetchgit/default.nix

@@ -7,9 +7,7 @@
 
     short = builtins.substring 0 7 rev;
 
-    appendShort = if (builtins.match "[a-f0-9]*" rev) != null
-      then "-${short}"
-      else "";
+    appendShort = lib.optionalString ((builtins.match "[a-f0-9]*" rev) != null) "-${short}";
   in "${if matched == null then base else builtins.head matched}${appendShort}";
 in
 { url, rev ? "HEAD", md5 ? "", sha256 ? "", hash ? "", leaveDotGit ? deepClone