treewide: use lib.optionalAttrs

pkgs/build-support/release/default.nix

···
 rec {
 
   sourceTarball = args: import ./source-tarball.nix (
-    { inherit stdenv autoconf automake libtool;
+    { inherit lib stdenv autoconf automake libtool;
     } // args);
 
   makeSourceTarball = sourceTarball; # compatibility

pkgs/build-support/release/nix-build.nix

···
 
   //
 
-  (if buildOutOfSourceTree
-   then {
+  (lib.optionalAttrs buildOutOfSourceTree
+   {
      preConfigure =
        # Build out of source tree and make the source tree read-only.  This
        # helps catch violations of the GNU Coding Standards (info
···
           ${lib.optionalString (preConfigure != null) preConfigure}
        '';
    }
-   else {})
+  )
 )

pkgs/build-support/release/source-tarball.nix

···
     if officialRelease
     then ""
     else "pre${toString (src.rev or src.revCount or "")}"
-, src, stdenv, autoconf, automake, libtool
+, src, lib, stdenv, autoconf, automake, libtool
 , # By default, provide all the GNU Build System as input.
   bootstrapBuildInputs ? [ autoconf automake libtool ]
 , ... } @ args:
···
   }
 
   # Then, the caller-supplied attributes.
-  // args //
+  // (builtins.removeAttrs args [ "lib" ]) //
 
   # And finally, our own stuff.
   {
···
       version = version + versionSuffix;
     };
 
-    meta = (if args ? meta then args.meta else {}) // {
+    meta = (lib.optionalAttrs (args ? meta) args.meta) // {
       description = "Source distribution";
 
       # Tarball builds are generally important, so give them a high

pkgs/top-level/all-packages.nix

···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "4.8" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "4.8");
 
     isl = if !stdenv.isDarwin then isl_0_14 else null;
     cloog = if !stdenv.isDarwin then cloog else null;
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "4.9" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "4.9");
 
     isl = if !stdenv.isDarwin then isl_0_11 else null;
 
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "6" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "6");
 
     # gcc 10 is too strict to cross compile gcc <= 8
     stdenv = if (stdenv.targetPlatform != stdenv.buildPlatform) && stdenv.cc.isGNU then gcc7Stdenv else stdenv;
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "7" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "7");
 
     # gcc 10 is too strict to cross compile gcc <= 8
     stdenv = if (stdenv.targetPlatform != stdenv.buildPlatform) && stdenv.cc.isGNU then gcc7Stdenv else stdenv;
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "8" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "8");
 
     # gcc 10 is too strict to cross compile gcc <= 8
     stdenv = if (stdenv.targetPlatform != stdenv.buildPlatform) && stdenv.cc.isGNU then gcc7Stdenv else stdenv;
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "9" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "9");
 
     isl = if !stdenv.isDarwin then isl_0_20 else null;
   }));
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "10" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "10");
 
     isl = if !stdenv.isDarwin then isl_0_20 else null;
   }));
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "11" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "11");
 
     isl = if !stdenv.isDarwin then isl_0_20 else null;
   }));
···
     profiledCompiler = false;
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
-    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCrossFor "12" else { };
+    threadsCross = lib.optionalAttrs (stdenv.targetPlatform != stdenv.buildPlatform) (threadsCrossFor "12");
 
     isl = if !stdenv.isDarwin then isl_0_20 else null;
   }));
···
 
   threadsCross = threadsCrossFor null;
   threadsCrossFor = cc_version:
-    if stdenv.targetPlatform.isMinGW && !(stdenv.targetPlatform.useLLVM or false)
-    then {
+    lib.optionalAttrs (stdenv.targetPlatform.isMinGW && !(stdenv.targetPlatform.useLLVM or false)) {
       # other possible values: win32 or posix
       model = "mcf";
       # For win32 or posix set this to null
···
         if cc_version == null || lib.versionAtLeast cc_version "13"
         then targetPackages.windows.mcfgthreads or windows.mcfgthreads
         else targetPackages.windows.mcfgthreads_pre_gcc_13 or windows.mcfgthreads_pre_gcc_13;
-    } else { };
+    };
 
   wasilibc = callPackage ../development/libraries/wasilibc {
     stdenv = crossLibcStdenv;