[Fix] no-cycle: should not warn for Flow imports

CHANGELOG.md

@@ -21,6 +21,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 - [`prefer-default-export`]: fix false positive with type export ([#1506], thanks [@golopot])
 - [`extensions`]: Fix `ignorePackages` to produce errors ([#1521], thanks [@saschanaz])
 - [`no-unused-modules`]: fix crash due to `export *` ([#1496], thanks [@Taranys])
+- [`no-cycle`]: should not warn for Flow imports ([#1494], thanks [@maxmalov])
 
 ### Docs
 - [`no-useless-path-segments`]: add docs for option `commonjs` ([#1507], thanks [@golopot])
@@ -629,6 +630,7 @@ for info on changes for earlier releases.
 [#1506]: https://github.com/benmosher/eslint-plugin-import/pull/1506
 [#1496]: https://github.com/benmosher/eslint-plugin-import/pull/1496
 [#1495]: https://github.com/benmosher/eslint-plugin-import/pull/1495
+[#1494]: https://github.com/benmosher/eslint-plugin-import/pull/1494
 [#1472]: https://github.com/benmosher/eslint-plugin-import/pull/1472
 [#1470]: https://github.com/benmosher/eslint-plugin-import/pull/1470
 [#1436]: https://github.com/benmosher/eslint-plugin-import/pull/1436
@@ -1019,3 +1021,4 @@ for info on changes for earlier releases.
 [@saschanaz]: https://github.com/saschanaz
 [@brettz9]: https://github.com/brettz9
 [@Taranys]: https://github.com/Taranys
+[@maxmalov]: https://github.com/maxmalov

src/ExportMap.js

@@ -404,19 +404,27 @@ ExportMap.parse = function (path, content, context) {
 
   function captureDependency(declaration) {
     if (declaration.source == null) return null
+    if (declaration.importKind === 'type') return null // skip Flow type imports
     const importedSpecifiers = new Set()
     const supportedTypes = new Set(['ImportDefaultSpecifier', 'ImportNamespaceSpecifier'])
+    let hasImportedType = false
     if (declaration.specifiers) {
       declaration.specifiers.forEach(specifier => {
-        if (supportedTypes.has(specifier.type)) {
+        const isType = specifier.importKind === 'type'
+        hasImportedType = hasImportedType || isType
+
+        if (supportedTypes.has(specifier.type) && !isType) {
           importedSpecifiers.add(specifier.type)
         }
-        if (specifier.type === 'ImportSpecifier') {
+        if (specifier.type === 'ImportSpecifier' && !isType) {
           importedSpecifiers.add(specifier.imported.name)
         }
       })
     }
 
+    // only Flow types were imported
+    if (hasImportedType && importedSpecifiers.size === 0) return null
+
     const p = remotePath(declaration.source.value)
     if (p == null) return null
     const existing = m.imports.get(p)

tests/files/cycles/flow-types-depth-one.js

@@ -0,0 +1,6 @@
+// @flow
+
+import type { FooType } from './flow-types-depth-two';
+import { type BarType, bar } from './flow-types-depth-two';
+
+export { bar }

tests/files/cycles/flow-types-depth-two.js

@@ -0,0 +1 @@
+import { foo } from './depth-one'

tests/files/cycles/flow-types.js

@@ -0,0 +1,6 @@
+// @flow
+
+import type { FooType } from './flow-types-depth-two';
+import { type BarType } from './flow-types-depth-two';
+
+export const bar = 1;

tests/src/rules/no-cycle.js

@@ -53,6 +53,10 @@ ruleTester.run('no-cycle', rule, {
       code: 'import type { FooType, BarType } from "./depth-one"',
       parser: require.resolve('babel-eslint'),
     }),
+    test({
+      code: 'import { bar } from "./flow-types"',
+      parser: require.resolve('babel-eslint'),
+    }),
   ],
   invalid: [
     test({
@@ -120,6 +124,11 @@ ruleTester.run('no-cycle', rule, {
       errors: [error(`Dependency cycle via ./depth-two:1=>./depth-one:1`)],
       parser: require.resolve('babel-eslint'),
     }),
+    test({
+      code: 'import { bar } from "./flow-types-depth-one"',
+      parser: require.resolve('babel-eslint'),
+      errors: [error(`Dependency cycle via ./flow-types-depth-two:4=>./depth-one:1`)],
+    }),
   ],
 })
 // })