Enable unicorn/prefer-spread

.eslintrc.yml

@@ -73,6 +73,7 @@ rules:
   unicorn/prefer-includes: error
   unicorn/prefer-number-properties: error
   unicorn/prefer-regexp-test: error
+  unicorn/prefer-spread: error
   unicorn/prefer-string-slice: error
 overrides:
   - files:

package.json

@@ -111,7 +111,7 @@
     "eslint-plugin-jest": "24.1.3",
     "eslint-plugin-prettier-internal-rules": "link:scripts/tools/eslint-plugin-prettier-internal-rules",
     "eslint-plugin-react": "7.22.0",
-    "eslint-plugin-unicorn": "26.0.1",
+    "eslint-plugin-unicorn": "fisker/eslint-plugin-unicorn#more-concat-fix",
     "execa": "5.0.0",
     "jest": "26.6.3",
     "jest-snapshot-serializer-ansi": "1.0.0",

scripts/build/build.js

@@ -97,9 +97,7 @@ async function createBundle(bundleConfig, cache, options) {
         const esmFile = path.join("dist/esm", output.replace(".js", ".mjs"));
         sizeTexts.push(`esm ${await getSizeText(esmFile)}`);
       }
-      process.stdout.write(
-        fitTerminal(output, sizeTexts.join(", ").concat(" "))
-      );
+      process.stdout.write(fitTerminal(output, [...sizeTexts.join(", "), " "]));
     }
 
     console.log(status.DONE);

scripts/build/config.js

@@ -168,7 +168,7 @@ function getFileOutput(bundle) {
   return bundle.output || path.basename(bundle.input);
 }
 
-module.exports = coreBundles.concat(parsers).map((bundle) => ({
+module.exports = [...coreBundles, ...parsers].map((bundle) => ({
   ...bundle,
   output: getFileOutput(bundle),
 }));

scripts/release/utils.js

@@ -37,7 +37,7 @@ function runYarn(script) {
   if (typeof script === "string") {
     script = [script];
   }
-  return execa("yarn", ["--silent"].concat(script)).catch((error) => {
+  return execa("yarn", ["--silent", ...script]).catch((error) => {
     throw new Error(`\`yarn ${script}\` failed\n${error.stdout}`);
   });
 }

scripts/sync-flow-tests.js

@@ -101,9 +101,9 @@ function run(argv) {
         "but that's not interesting for Prettier's tests.",
         "This is the skipped stuff:",
         "",
-      ]
-        .concat(skipped, "")
-        .join("\n")
+        ...skipped,
+        "",
+      ].join("\n")
     );
   }
 

src/cli/expand-patterns.js

@@ -130,9 +130,10 @@ function* expandPatternsInternal(context) {
       const filenames = flat(
         context.languages.map((lang) => lang.filenames || [])
       );
-      supportedFilesGlob = `**/{${extensions
-        .map((ext) => "*" + (ext[0] === "." ? ext : "." + ext))
-        .concat(filenames)}}`;
+      supportedFilesGlob = `**/{${[
+        ...extensions.map((ext) => "*" + (ext[0] === "." ? ext : "." + ext)),
+        ...filenames,
+      ]}}`;
     }
     return supportedFilesGlob;
   }

src/cli/usage.js

@@ -148,7 +148,7 @@ function createUsage(context) {
     return `${category} options:\n\n${indent(categoryOptions, 2)}`;
   });
 
-  return [constant.usageSummary].concat(optionsUsage, [""]).join("\n\n");
+  return [constant.usageSummary, ...optionsUsage, ""].join("\n\n");
 }
 
 function createDetailedUsage(context, flag) {

src/common/load-plugins.js

@@ -85,19 +85,20 @@ function load(plugins, pluginSearchDirs) {
         requirePath: resolve(pluginName, { paths: [resolvedPluginSearchDir] }),
       }));
     })
-    .reduce((a, b) => a.concat(b), []);
+    .reduce((a, b) => [...a, ...b], []);
 
-  const externalPlugins = uniqBy(
-    externalManualLoadPluginInfos.concat(externalAutoLoadPluginInfos),
-    "requirePath"
-  )
-    .map((externalPluginInfo) => ({
+  const externalPlugins = [
+    ...uniqBy(
+      [...externalManualLoadPluginInfos, ...externalAutoLoadPluginInfos],
+      "requirePath"
+    ).map((externalPluginInfo) => ({
       name: externalPluginInfo.name,
       ...eval("require")(externalPluginInfo.requirePath),
-    }))
-    .concat(externalPluginInstances);
+    })),
+    ...externalPluginInstances,
+  ];
 
-  return internalPlugins.concat(externalPlugins);
+  return [...internalPlugins, ...externalPlugins];
 }
 
 function findPluginsInNodeModules(nodeModulesDir) {

src/config/resolve-config.js

@@ -155,8 +155,8 @@ function mergeOverrides(configResult, filePath) {
 
 // Based on eslint: https://github.com/eslint/eslint/blob/master/lib/config/config-ops.js
 function pathMatchesGlobs(filePath, patterns, excludedPatterns) {
-  const patternList = [].concat(patterns);
-  const excludedPatternList = [].concat(excludedPatterns || []);
+  const patternList = [...patterns];
+  const excludedPatternList = [...(excludedPatterns || [])];
   const opts = { matchBase: true, dot: true };
 
   return (

src/document/doc-printer.js

@@ -45,7 +45,7 @@ function generateInd(ind, newPart, options) {
   const queue =
     newPart.type === "dedent"
       ? ind.queue.slice(0, -1)
-      : ind.queue.concat(newPart);
+      : [...ind.queue, ...newPart];
 
   let value = "";
   let length = 0;

src/language-css/parser-postcss.js

@@ -73,7 +73,7 @@ function parseValueNode(valueNode, options) {
       for (let i = 0; i < groups.length; i++) {
         const group = groups[i];
         if (group.type === "comma_group") {
-          groupList = groupList.concat(group.groups);
+          groupList = [...groupList, ...group.groups];
         } else {
           groupList.push(group);
         }

src/language-css/utils.js

@@ -30,7 +30,7 @@ const colorAdjusterFunctions = new Set([
 ]);
 
 function getAncestorCounter(path, typeOrTypes) {
-  const types = [].concat(typeOrTypes);
+  const types = [...typeOrTypes];
 
   let counter = -1;
   let ancestorNode;
@@ -149,7 +149,7 @@ function insideICSSRuleNode(path) {
 }
 
 function insideAtRuleNode(path, atRuleNameOrAtRuleNames) {
-  const atRuleNames = [].concat(atRuleNameOrAtRuleNames);
+  const atRuleNames = [...atRuleNameOrAtRuleNames];
   const atRuleAncestorNode = getAncestorNode(path, "css-atrule");
 
   return (

src/language-html/index.js

@@ -17,9 +17,10 @@ const languages = [
     since: "1.15.0",
     parsers: ["html"],
     vscodeLanguageIds: ["html"],
-    extensions: data.extensions.concat([
+    extensions: [
+      ...data.extensions,
       ".mjml", // MJML is considered XML in Linguist but it should be formatted as HTML
-    ]),
+    ],
   })),
   createLanguage(require("linguist-languages/data/HTML.json"), () => ({
     name: "Lightning Web Components",

src/language-html/print-preprocess.js

@@ -331,7 +331,7 @@ function extractWhitespaces(ast /*, options*/) {
         // extract whitespace nodes
         .reduce((newChildren, child) => {
           if (child.type !== "text" || isWhitespaceSensitive) {
-            return newChildren.concat(child);
+            return [...newChildren, child];
           }
 
           const localChildren = [];
@@ -361,7 +361,7 @@ function extractWhitespaces(ast /*, options*/) {
             localChildren.push({ type: TYPE_WHITESPACE });
           }
 
-          return newChildren.concat(localChildren);
+          return [...newChildren, ...localChildren];
         }, [])
         // set hasLeadingSpaces/hasTrailingSpaces and filter whitespace nodes
         .reduce((newChildren, child, i, children) => {
@@ -375,11 +375,14 @@ function extractWhitespaces(ast /*, options*/) {
             i !== children.length - 1 &&
             children[i + 1].type === TYPE_WHITESPACE;
 
-          return newChildren.concat({
-            ...child,
-            hasLeadingSpaces,
-            hasTrailingSpaces,
-          });
+          return [
+            ...newChildren,
+            {
+              ...child,
+              hasLeadingSpaces,
+              hasTrailingSpaces,
+            },
+          ];
         }, []),
     });
   });

src/language-html/printer-html.js

@@ -228,13 +228,13 @@ function genericPrint(path, options, print) {
     case "element":
     case "ieConditionalComment": {
       if (shouldPreserveContent(node, options)) {
-        return [].concat(
+        return [
           printOpeningTagPrefix(node, options),
           group(printOpeningTag(path, options, print)),
           replaceEndOfLineWith(getNodeContent(node, options), literalline),
           printClosingTag(node, options),
-          printClosingTagSuffix(node, options)
-        );
+          printClosingTagSuffix(node, options),
+        ];
       }
       /**
        * do not break:
@@ -505,23 +505,23 @@ function printChildren(path, options, print) {
       }
     }
 
-    return [].concat(
-      prevParts,
+    return [
+      ...prevParts,
       group([
         ...leadingParts,
         group([printChild(childPath), ...trailingParts], {
           id: groupIds[childIndex],
         }),
       ]),
-      nextParts
-    );
+      ...nextParts,
+    ];
   }, "children");
 
   function printChild(childPath) {
     const child = childPath.getValue();
 
     if (hasPrettierIgnore(child)) {
-      return [].concat(
+      return [
         printOpeningTagPrefix(child, options),
         replaceEndOfLineWith(
           options.originalText.slice(
@@ -536,8 +536,8 @@ function printChildren(path, options, print) {
           ),
           literalline
         ),
-        printClosingTagSuffix(child, options)
-      );
+        printClosingTagSuffix(child, options),
+      ];
     }
 
     return print(childPath);

src/language-js/clean.js

@@ -103,7 +103,7 @@ function clean(ast, newObj, parent) {
       .map((container) => container.expression);
 
     const quasis = templateLiterals.reduce(
-      (quasis, templateLiteral) => quasis.concat(templateLiteral.quasis),
+      (quasis, templateLiteral) => [...quasis, ...templateLiteral.quasis],
       []
     );
 

src/language-js/print/angular.js

@@ -12,12 +12,12 @@ function printAngular(path, options, print) {
   const n = path.getValue();
   switch (n.type) {
     case "NGRoot":
-      return [].concat(
+      return [
         path.call(print, "node"),
-        !hasComment(n.node)
+        ...(!hasComment(n.node)
           ? []
-          : [" //", getComments(n.node)[0].value.trimEnd()]
-      );
+          : [" //", getComments(n.node)[0].value.trimEnd()]),
+      ];
     case "NGPipeExpression":
       return printBinaryishExpression(path, options, print);
     case "NGChainedExpression":

src/language-js/print/binaryish.js

@@ -196,7 +196,8 @@ function printBinaryishExpressions(
     // which is unique in that it is right-associative.)
     if (shouldFlatten(node.operator, node.left.operator)) {
       // Flatten them out by recursively calling this function.
-      parts = parts.concat(
+      parts = [
+        ...parts,
         path.call(
           (left) =>
             printBinaryishExpressions(
@@ -207,8 +208,8 @@ function printBinaryishExpressions(
               isInsideParenthesis
             ),
           "left"
-        )
-      );
+        ),
+      ];
     } else {
       parts.push(group(path.call(print, "left")));
     }

src/language-js/print/call-arguments.js

@@ -159,12 +159,14 @@ function printCallArguments(path, options, print) {
             hasEmptyLineFollowingFirstArg ? hardline : line,
             hasEmptyLineFollowingFirstArg ? hardline : "",
           ],
-        ].concat(printedArguments.slice(1));
+          ...printedArguments.slice(1),
+        ];
       }
       if (shouldGroupLast && i === args.length - 1) {
-        printedExpanded = printedArguments
-          .slice(0, -1)
-          .concat(argPath.call((p) => print(p, { expandLastArg: true })));
+        printedExpanded = [
+          ...printedArguments.slice(0, -1),
+          argPath.call((p) => print(p, { expandLastArg: true })),
+        ];
       }
     });
 

src/language-js/print/interface.js

@@ -63,12 +63,10 @@ function printInterface(path, options, print) {
     const printedExtends = extendsParts;
     if (shouldIndentOnlyHeritageClauses) {
       parts.push(
-        group(
-          partsGroup.concat(ifBreak(indent(printedExtends), printedExtends))
-        )
+        group([...partsGroup, ifBreak(indent(printedExtends), printedExtends)])
       );
     } else {
-      parts.push(group(indent(partsGroup.concat(printedExtends))));
+      parts.push(group(indent([...partsGroup, ...printedExtends])));
     }
   } else {
     parts.push(...partsGroup, ...extendsParts);

src/language-js/print/object.js

@@ -113,7 +113,7 @@ function printObject(path, options, print) {
   const props = propsAndLoc
     .sort((a, b) => a.loc - b.loc)
     .map((prop) => {
-      const result = separatorParts.concat(group(prop.printed));
+      const result = [...separatorParts, group(prop.printed)];
       separatorParts = [separator, line];
       if (
         (prop.node.type === "TSPropertySignature" ||
@@ -149,7 +149,7 @@ function printObject(path, options, print) {
     } else {
       printed = "...";
     }
-    props.push(separatorParts.concat(printed));
+    props.push([...separatorParts, printed]);
   }
 
   const lastElem = getLast(n[propertiesField]);

src/language-js/printer-estree.js

@@ -195,7 +195,7 @@ function genericPrint(path, options, printPath, args) {
   }
 
   if (decorators.length > 0) {
-    return group(decorators.concat(parts));
+    return group([...decorators, ...parts]);
   }
   return parts;
 }

src/language-markdown/index.js

@@ -9,7 +9,7 @@ const languages = [
     since: "1.8.0",
     parsers: ["markdown"],
     vscodeLanguageIds: ["markdown"],
-    filenames: data.filenames.concat(["README"]),
+    filenames: [...data.filenames, "README"],
     extensions: data.extensions.filter((extension) => extension !== ".mdx"),
   })),
   createLanguage(require("linguist-languages/data/Markdown.json"), () => ({

src/language-markdown/parser-markdown.js

@@ -64,7 +64,7 @@ function htmlToJsx() {
 
 function frontMatter() {
   const proto = this.Parser.prototype;
-  proto.blockMethods = ["frontMatter"].concat(proto.blockMethods);
+  proto.blockMethods = ["frontMatter", ...proto.blockMethods];
   proto.blockTokenizers.frontMatter = tokenizer;
 
   function tokenizer(eat, value) {