treewide: use lib.warnIf where appropriate

lib/modules.nix

@@ -37,7 +37,7 @@ let
     setAttrByPath
     toList
     types
-    warn
+    warnIf
     ;
   inherit (lib.options)
     isOption
@@ -516,8 +516,8 @@ rec {
       value = if opt ? apply then opt.apply res.mergedValue else res.mergedValue;
 
       warnDeprecation =
-        if opt.type.deprecationMessage == null then id
-        else warn "The type `types.${opt.type.name}' of option `${showOption loc}' defined in ${showFiles opt.declarations} is deprecated. ${opt.type.deprecationMessage}";
+        warnIf (opt.type.deprecationMessage != null)
+          "The type `types.${opt.type.name}' of option `${showOption loc}' defined in ${showFiles opt.declarations} is deprecated. ${opt.type.deprecationMessage}";
 
     in warnDeprecation opt //
       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;

lib/strings.nix

@@ -644,8 +644,8 @@ rec {
   floatToString = float: let
     result = toString float;
     precise = float == fromJSON result;
-  in if precise then result
-    else lib.warn "Imprecise conversion from float to string ${result}" result;
+  in lib.warnIf (!precise) "Imprecise conversion from float to string ${result}"
+    result;
 
   /* Check whether a value can be coerced to a string */
   isCoercibleToString = x:

nixos/lib/testing-python.nix

@@ -131,10 +131,8 @@ rec {
                   "it's currently ${toString testNameLen} characters long.")
             else
               "nixos-test-driver-${name}";
-
-          warn = if skipLint then lib.warn "Linting is disabled!" else lib.id;
         in
-        warn (runCommand testDriverName
+        lib.warnIf skipLint "Linting is disabled" (runCommand testDriverName
           {
             buildInputs = [ makeWrapper ];
             testScript = testScript';

pkgs/applications/networking/browsers/chromium/common.nix

@@ -112,10 +112,8 @@ let
 
   warnObsoleteVersionConditional = min-version: result:
     let ungoogled-version = (importJSON ./upstream-info.json).ungoogled-chromium.version;
-    in if versionAtLeast ungoogled-version min-version
-       then warn "chromium: ungoogled version ${ungoogled-version} is newer than a conditional bounded at ${min-version}. You can safely delete it."
-            result
-       else result;
+    in warnIf (versionAtLeast ungoogled-version min-version) "chromium: ungoogled version ${ungoogled-version} is newer than a conditional bounded at ${min-version}. You can safely delete it."
+      result;
   chromiumVersionAtLeast = min-version:
     let result = versionAtLeast upstream-info.version min-version;
     in  warnObsoleteVersionConditional min-version result;

pkgs/development/perl-modules/generic/default.nix

@@ -5,10 +5,8 @@
 assert attrs?pname -> attrs?version;
 assert attrs?pname -> !(attrs?name);
 
-(if attrs ? name then
-  lib.trivial.warn "builtPerlPackage: `name' (\"${attrs.name}\") is deprecated, use `pname' and `version' instead"
- else
-  (x: x))
+lib.warnIf (attrs ? name) "builtPerlPackage: `name' (\"${attrs.name}\") is deprecated, use `pname' and `version' instead"
+
 toPerlModule(stdenv.mkDerivation (
   (
   lib.recursiveUpdate

pkgs/servers/jellyfin/default.nix

@@ -11,9 +11,8 @@ let
     else if isAarch64 then "arm64"
     else lib.warn "Unsupported architecture, some image processing features might be unavailable" "unknown";
   musl = lib.optionalString stdenv.hostPlatform.isMusl
-    (if (arch != "x64")
-      then lib.warn "Some image processing features might be unavailable for non x86-64 with Musl" "musl-"
-      else "musl-");
+    (lib.warnIf (arch != "x64") "Some image processing features might be unavailable for non x86-64 with Musl"
+      "musl-");
   runtimeDir = "${os}-${musl}${arch}";
 
 in stdenv.mkDerivation rec {