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huangtiandi1999yefanautofix-ci[bot]camc314
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feat(linter): add eslint/block-scoped-var (#10237)
Relates to #479 Rule detail：https://eslint.org/docs/latest/rules/block-scoped-var --------- Co-authored-by: yefan <[email protected]> Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com> Co-authored-by: Cameron <[email protected]>
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‎crates/oxc_linter/src/rules.rs

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@@ -38,6 +38,7 @@ mod import {
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mod eslint {
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pub mod array_callback_return;
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pub mod block_scoped_var;
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pub mod curly;
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pub mod default_case;
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pub mod default_case_last;
@@ -561,6 +562,7 @@ oxc_macros::declare_all_lint_rules! {
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// import::no_deprecated,
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// import::no_unused_modules,
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eslint::array_callback_return,
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eslint::block_scoped_var,
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eslint::curly,
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eslint::default_case,
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eslint::default_case_last,

‎crates/oxc_linter/src/rules/eslint/block_scoped_var.rs

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@@ -0,0 +1,319 @@
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use oxc_ast::{AstKind, ast::VariableDeclarationKind};
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use oxc_diagnostics::OxcDiagnostic;
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use oxc_macros::declare_oxc_lint;
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use oxc_span::Span;
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use crate::{AstNode, context::LintContext, rule::Rule};
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fn block_scoped_var_diagnostic(span: Span, name: &str) -> OxcDiagnostic {
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OxcDiagnostic::warn(format!("'{name}' is used outside of binding context."))
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.with_help(format!("Variable '{name}' is used outside its declaration block. Declare it outside the block or use 'let'/'const'."))
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.with_label(span)
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}
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#[derive(Debug, Default, Clone)]
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pub struct BlockScopedVar;
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declare_oxc_lint!(
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/// ### What it does
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///
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/// Generates warnings when variables are used outside of the block in which they were defined.
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/// This emulates C-style block scope.
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///
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/// ### Why is this bad?
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///
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/// This rule aims to reduce the usage of variables outside of their binding context
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/// and emulate traditional block scope from other languages.
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/// This is to help newcomers to the language avoid difficult bugs with variable hoisting.
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///
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/// ### Examples
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///
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/// Examples of **incorrect** code for this rule:
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/// ```js
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/// function doIf() {
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/// if (true) {
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/// var build = true;
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/// }
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/// console.log(build);
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/// }
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/// ```
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///
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/// Examples of **correct** code for this rule:
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/// ```js
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/// function doIf() {
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/// var build;
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/// if (true) {
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/// build = true;
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/// }
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/// console.log(build);
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/// }
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///
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/// ```
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BlockScopedVar,
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eslint,
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suspicious,
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);
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impl Rule for BlockScopedVar {
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fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
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let AstKind::VariableDeclaration(decl) = node.kind() else {
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return;
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};
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if decl.kind != VariableDeclarationKind::Var {
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return;
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}
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let cur_node_scope_id = node.scope_id();
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if !ctx.scoping().scope_flags(cur_node_scope_id).is_strict_mode() {
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return;
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}
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// `scope_arr` contains all the scopes that are children of the current scope
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// we should eliminate all of them
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let scope_arr = ctx.scoping().iter_all_scope_child_ids(node.scope_id()).collect::<Vec<_>>();
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let declarations = &decl.declarations;
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for item in declarations {
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let id = &item.id;
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// e.g. "var [a, b] = [1, 2]"
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for ident in id.get_binding_identifiers() {
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let name = ident.name.as_str();
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let Some(symbol_id) = ctx.scoping().find_binding(node.scope_id(), name) else {
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continue;
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};
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// e.g. "if (true} { var a = 4; } else { var a = 4; }"
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// in this case we can't find the reference of 'a' by call `get_resolved_references`
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// so i use `symbol_redeclarations` to find all the redeclarations
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for redeclaration in ctx.scoping().symbol_redeclarations(symbol_id) {
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let re_scope_id = ctx.nodes().get_node(redeclaration.declaration).scope_id();
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if !scope_arr.contains(&re_scope_id) && re_scope_id != cur_node_scope_id {
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ctx.diagnostic(block_scoped_var_diagnostic(redeclaration.span, name));
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}
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}
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// e.g. "var a = 4; console.log(a);"
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for reference in ctx.scoping().get_resolved_references(symbol_id) {
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let reference_scope_id = ctx.nodes().get_node(reference.node_id()).scope_id();
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if !scope_arr.contains(&reference_scope_id)
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&& reference_scope_id != cur_node_scope_id
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{
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ctx.diagnostic(block_scoped_var_diagnostic(
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ctx.reference_span(reference),
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name,
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));
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}
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}
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}
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}
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}
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}
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#[test]
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fn test() {
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use crate::tester::Tester;
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let pass = vec![
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"if (1) {
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var a = 4;
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} else {
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let a = 4;
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console.log(a);
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}",
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"function f() { } f(); var exports = { f: f };",
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"var f = () => {}; f(); var exports = { f: f };",
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"!function f(){ f; }",
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"function f() { } f(); var exports = { f: f };",
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"function f() { var a, b; { a = true; } b = a; }",
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"var a; function f() { var b = a; }",
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"function f(a) { }",
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"!function(a) { };",
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"!function f(a) { };",
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"function f(a) { var b = a; }",
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"!function f(a) { var b = a; };",
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"function f() { var g = f; }",
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"function f() { } function g() { var f = g; }",
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"function f() { var hasOwnProperty; { hasOwnProperty; } }",
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"function f(){ a; b; var a, b; }",
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"function f(){ g(); function g(){} }",
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"if (true) { var a = 1; a; }",
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"var a; if (true) { a; }",
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"for (var i = 0; i < 10; i++) { i; }",
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"var i; for(i; i; i) { i; }",
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r#"
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function myFunc(foo) { "use strict"; var { bar } = foo; bar.hello();}
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"#,
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r#"
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function myFunc(foo) { "use strict"; var [ bar ] = foo; bar.hello();}
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"#,
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r#"
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const React = require("react/addons");const cx = React.addons.classSet;
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"#,
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r#"import * as y from "./other.js"; y();"#,
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"var v = 1; function x() { return v; };",
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"function myFunc(...foo) { return foo;}",
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"var f = () => { var g = f; }",
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"class Foo {}\nexport default Foo;",
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"foo; class C { static {} } var foo; ",
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"var foo; class C { static {} [foo]; } ",
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"class C { static { foo; } } var foo;",
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"var foo; class C { static { foo; } } ",
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"class C { static { if (bar) { foo; } var foo; } }",
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"class C { static { foo; var foo; } }",
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"class C { static { var foo; foo; } }",
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"(function () { foo(); })(); function foo() {}",
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"(function () { foo(); })(); function foo() {}",
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"foo: while (true) { bar: for (var i = 0; i < 13; ++i) {if (i === 7) break foo; } }",
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"foo: while (true) { bar: for (var i = 0; i < 13; ++i) {if (i === 7) continue foo; } }",
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"var a = { foo: bar };",
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"var a = { foo: foo };",
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"var a = { bar: 7, foo: bar };",
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"var a = arguments;",
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r#"
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function a(n) { return n > 0 ? b(n - 1) : "a"; } function b(n) { return n > 0 ? a(n - 1) : "b"; }
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"#,
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"const { dummy: { data, isLoading }, auth: { isLoggedIn } } = this.props;",
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"/*global prevState*/ const { virtualSize: prevVirtualSize = 0 } = prevState;",
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"/*global React*/ let {PropTypes, addons: {PureRenderMixin}} = React; let Test = React.createClass({mixins: [PureRenderMixin]});",
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r"
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function doIf() {
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var build;
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if (true) {
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build = true;
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}
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console.log(build);
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}
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",
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r"
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function doIfElse() {
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var build;
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if (true) {
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build = true;
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} else {
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build = false;
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}
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}
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",
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r"
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function doTryCatch() {
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var build;
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var f;
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try {
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build = 1;
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} catch (e) {
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f = build;
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}
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}
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",
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];
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let fail = vec![
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r"
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if (true) {
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var a = 3;
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} else {
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var b = 4;
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var a = 4;
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}
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console.log(a, b);
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",
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r"
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if (true) {
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var [a, b] = [1, 2];
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}
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console.log(a, b);
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",
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r"
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if (true) {
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var a = 4, b = 3;
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}
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console.log(a, b);
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",
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r"
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if (true) {
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{
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var a = 4, b = 3;
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}
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var a = 4;
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}
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",
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"function f(){ x; { var x; } }",
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"function f(){ { var x; } x; }",
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"function f() { var a; { var b = 0; } a = b; }",
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"function f() { try { var a = 0; } catch (e) { var b = a; } }",
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"function a() { for(var b in {}) { var c = b; } c; }",
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"function a() { for(var b of {}) { var c = b; } c; }",
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"function f(){ switch(2) { case 1: var b = 2; b; break; default: b; break;} b; }",
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"for (var a = 0;;) {} a;",
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"for (var a in []) {} a;",
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"for (var a of []) {} a;",
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"{ var a = 0; } a;",
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"if (true) { var a; } a;",
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"if (true) { var a = 1; } else { var a = 2; }",
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"for (var i = 0;;) {} for(var i = 0;;) {}",
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"class C { static { if (bar) { var foo; } foo; } }",
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"{ var foo, bar; } bar;",
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"if (foo) { var a = 1; } else if (bar) { var a = 2; } else { var a = 3; }",
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r"
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if (true) {
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var build = true;
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console.log(build);
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{
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conosole.log(build);
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{
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console.log(build);
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}
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}
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}
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console.log(build);
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let t = build;
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",
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r"
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function doIf() {
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if (true) {
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var build = true;
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}
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console.log(build);
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}
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",
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r"
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function doIfElse() {
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if (true) {
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var build = true;
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} else {
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var build = false;
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}
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}
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",
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r"
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function doTryCatch() {
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try {
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var build = 1;
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} catch (e) {
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var f = build;
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}
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}
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",
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r"
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function doFor() {
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for (var x = 1; x < 10; x++) {
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var y = f(x);
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}
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console.log(y);
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}
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",
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r"
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class C {
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static {
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if (something) {
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var build = true;
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}
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build = false;
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}
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}
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",
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];
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Tester::new(BlockScopedVar::NAME, BlockScopedVar::PLUGIN, pass, fail).test_and_snapshot();
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}

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