Do not move let and const out of for initializers. Closes #997

terser · Jan 27, 2023 · 79d7613 · 79d7613
1 parent c14d512
commit 79d7613
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Showing 5 changed files with 30 additions and 4 deletions.
diff --git a/README.md b/README.md
@@ -758,7 +758,7 @@ If you happen to need the source map as a raw object, set `sourceMap.asObject` t
   - `3` -- inline functions with arguments and variables
   - `true` -- same as `3`
 
-- `join_vars` (default: `true`) -- join consecutive `var` statements
+- `join_vars` (default: `true`) -- join consecutive `var`, `let` and `const` statements
 
 - `keep_classnames` (default: `false`) -- Pass `true` to prevent the compressor from
   discarding class names. Pass a regular expression to only keep class names matching

diff --git a/lib/ast.js b/lib/ast.js
@@ -994,6 +994,7 @@ var AST_Jump = DEFNODE("Jump", null, function AST_Jump(props) {
     $documentation: "Base class for “jumps” (for now that's `return`, `throw`, `break` and `continue`)"
 }, AST_Statement);
 
+/** Base class for “exits” (`return` and `throw`) */
 var AST_Exit = DEFNODE("Exit", "value", function AST_Exit(props) {
     if (props) {
         this.value = props.value;

diff --git a/lib/compress/tighten-body.js b/lib/compress/tighten-body.js
@@ -1404,14 +1404,21 @@ export function tighten_body(statements, compressor) {
                     CHANGED = true;
                     stat.init = exprs.length ? make_sequence(stat.init, exprs) : null;
                     statements[++j] = stat;
-                } else if (prev instanceof AST_Var && (!stat.init || stat.init.TYPE == prev.TYPE)) {
+                } else if (
+                    prev instanceof AST_Var
+                    && (!stat.init || stat.init.TYPE == prev.TYPE)
+                ) {
                     if (stat.init) {
                         prev.definitions = prev.definitions.concat(stat.init.definitions);
                     }
                     stat.init = prev;
                     statements[j] = stat;
                     CHANGED = true;
-                } else if (defs && stat.init && defs.TYPE == stat.init.TYPE && declarations_only(stat.init)) {
+                } else if (
+                    defs instanceof AST_Var
+                    && stat.init instanceof AST_Var
+                    && declarations_only(stat.init)
+                ) {
                     defs.definitions = defs.definitions.concat(stat.init.definitions);
                     stat.init = null;
                     statements[++j] = stat;

diff --git a/lib/scope.js b/lib/scope.js
@@ -69,6 +69,7 @@ import {
     AST_Export,
     AST_For,
     AST_ForIn,
+    AST_ForOf,
     AST_Function,
     AST_Import,
     AST_IterationStatement,
@@ -230,8 +231,9 @@ AST_Scope.DEFMETHOD("figure_out_scope", function(options, { parent_scope = null,
             scope.init_scope_vars(parent_scope);
             scope.uses_with = save_scope.uses_with;
             scope.uses_eval = save_scope.uses_eval;
+
             if (options.safari10) {
-                if (node instanceof AST_For || node instanceof AST_ForIn) {
+                if (node instanceof AST_For || node instanceof AST_ForIn || node instanceof AST_ForOf) {
                     for_scopes.push(scope);
                 }
             }

diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
@@ -4420,6 +4420,22 @@ issue_2497: {
     }
 }
 
+issue_997: {
+    options = {
+        defaults: true,
+    }
+    input: {
+        function main(e) {
+            console.log(e.length);
+            let other = "12";
+            for (let e; e = 0;)
+                console.log(e);
+        }
+        main("foo");
+    }
+    expect_stdout: ["3"]
+}
+
 issue_2506: {
     options = {
         collapse_vars: true,