Update: support ?? operator, import.meta, and export * as ns (#13196

)

* upgrade deps

* update code path analysis for nullish coalescing

* update rules for `export * as ns from "source"`

* add a few tests for import.meta

* update rules for nullish coalescing

* update deps

* add tests to no-restricted-imports

* add tests to camelcase

* add tests to id-blacklist

* add tests for id-match

docs/rules/no-mixed-operators.md

@@ -100,6 +100,7 @@ The following operators can be used in `groups` option:
 * Bitwise Operators: `"&"`, `"|"`, `"^"`, `"~"`, `"<<"`, `">>"`, `">>>"`
 * Comparison Operators: `"=="`, `"!="`, `"==="`, `"!=="`, `">"`, `">="`, `"<"`, `"<="`
 * Logical Operators: `"&&"`, `"||"`
+* Coalesce Operator: `"??"`
 * Relational Operators: `"in"`, `"instanceof"`
 * Ternary Operator: `?:`
 

lib/linter/code-path-analysis/code-path-analyzer.js

@@ -33,10 +33,10 @@ function isCaseNode(node) {
  * Checks whether the given logical operator is taken into account for the code
  * path analysis.
  * @param {string} operator The operator found in the LogicalExpression node
- * @returns {boolean} `true` if the operator is "&&" or "||"
+ * @returns {boolean} `true` if the operator is "&&" or "||" or "??"
  */
 function isHandledLogicalOperator(operator) {
-    return operator === "&&" || operator === "||";
+    return operator === "&&" || operator === "||" || operator === "??";
 }
 
 /**

lib/linter/code-path-analysis/code-path-state.js

@@ -201,6 +201,7 @@ function finalizeTestSegmentsOfFor(context, choiceContext, head) {
     if (!choiceContext.processed) {
         choiceContext.trueForkContext.add(head);
         choiceContext.falseForkContext.add(head);
+        choiceContext.qqForkContext.add(head);
     }
 
     if (context.test !== true) {
@@ -351,6 +352,7 @@ class CodePathState {
             isForkingAsResult,
             trueForkContext: ForkContext.newEmpty(this.forkContext),
             falseForkContext: ForkContext.newEmpty(this.forkContext),
+            qqForkContext: ForkContext.newEmpty(this.forkContext),
             processed: false
         };
     }
@@ -370,6 +372,7 @@ class CodePathState {
         switch (context.kind) {
             case "&&":
             case "||":
+            case "??":
 
                 /*
                  * If any result were not transferred from child contexts,
@@ -379,6 +382,7 @@ class CodePathState {
                 if (!context.processed) {
                     context.trueForkContext.add(headSegments);
                     context.falseForkContext.add(headSegments);
+                    context.qqForkContext.add(headSegments);
                 }
 
                 /*
@@ -390,6 +394,7 @@ class CodePathState {
 
                     parentContext.trueForkContext.addAll(context.trueForkContext);
                     parentContext.falseForkContext.addAll(context.falseForkContext);
+                    parentContext.qqForkContext.addAll(context.qqForkContext);
                     parentContext.processed = true;
 
                     return context;
@@ -456,13 +461,24 @@ class CodePathState {
              * This got segments already from the child choice context.
              * Creates the next path from own true/false fork context.
              */
-            const prevForkContext =
-                context.kind === "&&" ? context.trueForkContext
-                /* kind === "||" */ : context.falseForkContext;
+            let prevForkContext;
+
+            switch (context.kind) {
+                case "&&": // if true then go to the right-hand side.
+                    prevForkContext = context.trueForkContext;
+                    break;
+                case "||": // if false then go to the right-hand side.
+                    prevForkContext = context.falseForkContext;
+                    break;
+                case "??": // Both true/false can short-circuit, so needs the third path to go to the right-hand side. That's qqForkContext.
+                    prevForkContext = context.qqForkContext;
+                    break;
+                default:
+                    throw new Error("unreachable");
+            }
 
             forkContext.replaceHead(prevForkContext.makeNext(0, -1));
             prevForkContext.clear();
-
             context.processed = false;
         } else {
 
@@ -471,14 +487,19 @@ class CodePathState {
              * So addresses the head segments.
              * The head segments are the path of the left-hand operand.
              */
-            if (context.kind === "&&") {
-
-                // The path does short-circuit if false.
-                context.falseForkContext.add(forkContext.head);
-            } else {
-
-                // The path does short-circuit if true.
-                context.trueForkContext.add(forkContext.head);
+            switch (context.kind) {
+                case "&&": // the false path can short-circuit.
+                    context.falseForkContext.add(forkContext.head);
+                    break;
+                case "||": // the true path can short-circuit.
+                    context.trueForkContext.add(forkContext.head);
+                    break;
+                case "??": // both can short-circuit.
+                    context.trueForkContext.add(forkContext.head);
+                    context.falseForkContext.add(forkContext.head);
+                    break;
+                default:
+                    throw new Error("unreachable");
             }
 
             forkContext.replaceHead(forkContext.makeNext(-1, -1));
@@ -501,6 +522,7 @@ class CodePathState {
         if (!context.processed) {
             context.trueForkContext.add(forkContext.head);
             context.falseForkContext.add(forkContext.head);
+            context.qqForkContext.add(forkContext.head);
         }
 
         context.processed = false;

lib/rules/keyword-spacing.js

@@ -442,6 +442,12 @@ module.exports = {
                 checkSpacingAround(sourceCode.getTokenAfter(firstToken));
             }
 
+            if (node.type === "ExportAllDeclaration" && node.exported) {
+                const asToken = sourceCode.getTokenBefore(node.exported);
+
+                checkSpacingBefore(asToken, PREV_TOKEN_M);
+            }
+
             if (node.source) {
                 const fromToken = sourceCode.getTokenBefore(node.source);
 

lib/rules/no-extra-boolean-cast.js

@@ -172,6 +172,9 @@ module.exports = {
                 case "UnaryExpression":
                     return precedence(node) < precedence(parent);
                 case "LogicalExpression":
+                    if (astUtils.isMixedLogicalAndCoalesceExpressions(node, parent)) {
+                        return true;
+                    }
                     if (previousNode === parent.left) {
                         return precedence(node) < precedence(parent);
                     }

lib/rules/no-extra-parens.js

@@ -478,6 +478,7 @@ module.exports = {
             if (!shouldSkipLeft && hasExcessParens(node.left)) {
                 if (
                     !(node.left.type === "UnaryExpression" && isExponentiation) &&
+                    !astUtils.isMixedLogicalAndCoalesceExpressions(node.left, node) &&
                     (leftPrecedence > prec || (leftPrecedence === prec && !isExponentiation)) ||
                     isParenthesisedTwice(node.left)
                 ) {
@@ -487,6 +488,7 @@ module.exports = {
 
             if (!shouldSkipRight && hasExcessParens(node.right)) {
                 if (
+                    !astUtils.isMixedLogicalAndCoalesceExpressions(node.right, node) &&
                     (rightPrecedence > prec || (rightPrecedence === prec && isExponentiation)) ||
                     isParenthesisedTwice(node.right)
                 ) {

lib/rules/no-mixed-operators.js

@@ -21,13 +21,15 @@ const COMPARISON_OPERATORS = ["==", "!=", "===", "!==", ">", ">=", "<", "<="];
 const LOGICAL_OPERATORS = ["&&", "||"];
 const RELATIONAL_OPERATORS = ["in", "instanceof"];
 const TERNARY_OPERATOR = ["?:"];
+const COALESCE_OPERATOR = ["??"];
 const ALL_OPERATORS = [].concat(
     ARITHMETIC_OPERATORS,
     BITWISE_OPERATORS,
     COMPARISON_OPERATORS,
     LOGICAL_OPERATORS,
     RELATIONAL_OPERATORS,
-    TERNARY_OPERATOR
+    TERNARY_OPERATOR,
+    COALESCE_OPERATOR
 );
 const DEFAULT_GROUPS = [
     ARITHMETIC_OPERATORS,
@@ -236,7 +238,6 @@ module.exports = {
         return {
             BinaryExpression: check,
             LogicalExpression: check
-
         };
     }
 };

lib/rules/no-restricted-exports.js

@@ -61,6 +61,12 @@ module.exports = {
         }
 
         return {
+            ExportAllDeclaration(node) {
+                if (node.exported) {
+                    checkExportedName(node.exported);
+                }
+            },
+
             ExportNamedDeclaration(node) {
                 const declaration = node.declaration;
 

lib/rules/no-unneeded-ternary.js

@@ -147,10 +147,12 @@ module.exports = {
                         loc: node.consequent.loc.start,
                         messageId: "unnecessaryConditionalAssignment",
                         fix: fixer => {
-                            const shouldParenthesizeAlternate = (
-                                astUtils.getPrecedence(node.alternate) < OR_PRECEDENCE &&
-                                !astUtils.isParenthesised(sourceCode, node.alternate)
-                            );
+                            const shouldParenthesizeAlternate =
+                                (
+                                    astUtils.getPrecedence(node.alternate) < OR_PRECEDENCE ||
+                                    astUtils.isCoalesceExpression(node.alternate)
+                                ) &&
+                                !astUtils.isParenthesised(sourceCode, node.alternate);
                             const alternateText = shouldParenthesizeAlternate
                                 ? `(${sourceCode.getText(node.alternate)})`
                                 : astUtils.getParenthesisedText(sourceCode, node.alternate);

lib/rules/utils/ast-utils.js

@@ -416,6 +416,53 @@ function equalTokens(left, right, sourceCode) {
     return true;
 }
 
+/**
+ * Check if the given node is a true logical expression or not.
+ *
+ * The three binary expressions logical-or (`||`), logical-and (`&&`), and
+ * coalesce (`??`) are known as `ShortCircuitExpression`.
+ * But ESTree represents those by `LogicalExpression` node.
+ *
+ * This function rejects coalesce expressions of `LogicalExpression` node.
+ * @param {ASTNode} node The node to check.
+ * @returns {boolean} `true` if the node is `&&` or `||`.
+ * @see https://tc39.es/ecma262/#prod-ShortCircuitExpression
+ */
+function isLogicalExpression(node) {
+    return (
+        node.type === "LogicalExpression" &&
+            (node.operator === "&&" || node.operator === "||")
+    );
+}
+
+/**
+ * Check if the given node is a nullish coalescing expression or not.
+ *
+ * The three binary expressions logical-or (`||`), logical-and (`&&`), and
+ * coalesce (`??`) are known as `ShortCircuitExpression`.
+ * But ESTree represents those by `LogicalExpression` node.
+ *
+ * This function finds only coalesce expressions of `LogicalExpression` node.
+ * @param {ASTNode} node The node to check.
+ * @returns {boolean} `true` if the node is `??`.
+ */
+function isCoalesceExpression(node) {
+    return node.type === "LogicalExpression" && node.operator === "??";
+}
+
+/**
+ * Check if given two nodes are the pair of a logical expression and a coalesce expression.
+ * @param {ASTNode} left A node to check.
+ * @param {ASTNode} right Another node to check.
+ * @returns {boolean} `true` if the two nodes are the pair of a logical expression and a coalesce expression.
+ */
+function isMixedLogicalAndCoalesceExpressions(left, right) {
+    return (
+        (isLogicalExpression(left) && isCoalesceExpression(right)) ||
+            (isCoalesceExpression(left) && isLogicalExpression(right))
+    );
+}
+
 //------------------------------------------------------------------------------
 // Public Interface
 //------------------------------------------------------------------------------
@@ -779,6 +826,7 @@ module.exports = {
             case "LogicalExpression":
                 switch (node.operator) {
                     case "||":
+                    case "??":
                         return 4;
                     case "&&":
                         return 5;
@@ -1538,5 +1586,9 @@ module.exports = {
      */
     hasOctalEscapeSequence(rawString) {
         return OCTAL_ESCAPE_PATTERN.test(rawString);
-    }
+    },
+
+    isLogicalExpression,
+    isCoalesceExpression,
+    isMixedLogicalAndCoalesceExpressions
 };

package.json

@@ -52,10 +52,10 @@
     "cross-spawn": "^7.0.2",
     "debug": "^4.0.1",
     "doctrine": "^3.0.0",
-    "eslint-scope": "^5.0.0",
+    "eslint-scope": "^5.1.0",
     "eslint-utils": "^2.0.0",
-    "eslint-visitor-keys": "^1.1.0",
-    "espree": "^7.0.0",
+    "eslint-visitor-keys": "^1.2.0",
+    "espree": "^7.1.0",
     "esquery": "^1.2.0",
     "esutils": "^2.0.2",
     "file-entry-cache": "^5.0.1",
@@ -86,7 +86,7 @@
   "devDependencies": {
     "@babel/core": "^7.4.3",
     "@babel/preset-env": "^7.4.3",
-    "acorn": "^7.1.1",
+    "acorn": "^7.2.0",
     "babel-loader": "^8.0.5",
     "chai": "^4.0.1",
     "cheerio": "^0.22.0",

tests/fixtures/code-path-analysis/logical--do-while-qq-1.js

@@ -0,0 +1,23 @@
+/*expected
+initial->s1_1->s1_2->s1_3->s1_2->s1_2;
+s1_3->s1_4;
+s1_2->s1_4->final;
+*/
+do {
+    foo();
+} while (a ?? b);
+
+/*DOT
+digraph {
+    node[shape=box,style="rounded,filled",fillcolor=white];
+    initial[label="",shape=circle,style=filled,fillcolor=black,width=0.25,height=0.25];
+    final[label="",shape=doublecircle,style=filled,fillcolor=black,width=0.25,height=0.25];
+    s1_1[label="Program\nDoWhileStatement"];
+    s1_2[label="BlockStatement\nExpressionStatement\nCallExpression\nIdentifier (foo)\nLogicalExpression\nIdentifier (a)\nIdentifier:exit (foo)\nCallExpression:exit\nExpressionStatement:exit\nBlockStatement:exit\nIdentifier:exit (a)"];
+    s1_3[label="Identifier (b)\nIdentifier:exit (b)\nLogicalExpression:exit"];
+    s1_4[label="DoWhileStatement:exit\nProgram:exit"];
+    initial->s1_1->s1_2->s1_3->s1_2->s1_2;
+    s1_3->s1_4;
+    s1_2->s1_4->final;
+}
+*/

tests/fixtures/code-path-analysis/logical--do-while-qq-2.js

@@ -0,0 +1,33 @@
+/*expected
+initial->s1_1->s1_2->s1_3->s1_4->s1_5->s1_2->s1_2;
+s1_3->s1_2;
+s1_4->s1_2;
+s1_5->s1_6;
+s1_2->s1_6;
+s1_3->s1_6;
+s1_4->s1_6->final;
+*/
+do {
+    foo();
+} while (a ?? b ?? c ?? d);
+
+/*DOT
+digraph {
+    node[shape=box,style="rounded,filled",fillcolor=white];
+    initial[label="",shape=circle,style=filled,fillcolor=black,width=0.25,height=0.25];
+    final[label="",shape=doublecircle,style=filled,fillcolor=black,width=0.25,height=0.25];
+    s1_1[label="Program\nDoWhileStatement"];
+    s1_2[label="BlockStatement\nExpressionStatement\nCallExpression\nIdentifier (foo)\nLogicalExpression\nLogicalExpression\nLogicalExpression\nIdentifier (a)\nIdentifier:exit (foo)\nCallExpression:exit\nExpressionStatement:exit\nBlockStatement:exit\nIdentifier:exit (a)"];
+    s1_3[label="Identifier (b)\nIdentifier:exit (b)\nLogicalExpression:exit"];
+    s1_4[label="Identifier (c)\nIdentifier:exit (c)\nLogicalExpression:exit"];
+    s1_5[label="Identifier (d)\nIdentifier:exit (d)\nLogicalExpression:exit"];
+    s1_6[label="DoWhileStatement:exit\nProgram:exit"];
+    initial->s1_1->s1_2->s1_3->s1_4->s1_5->s1_2->s1_2;
+    s1_3->s1_2;
+    s1_4->s1_2;
+    s1_5->s1_6;
+    s1_2->s1_6;
+    s1_3->s1_6;
+    s1_4->s1_6->final;
+}
+*/