fix corner case in reduce_vars (#5687)

lib/compress.js

@@ -497,6 +497,7 @@ Compressor.prototype.compress = function(node) {
     function has_escaped(d, scope, node, parent) {
         if (parent instanceof AST_Assign) return parent.operator == "=" && parent.right === node;
         if (parent instanceof AST_Call) return parent.expression !== node || parent instanceof AST_New;
+        if (parent instanceof AST_ClassField) return parent.value === node && !parent.static;
         if (parent instanceof AST_Exit) return parent.value === node && scope.resolve() !== d.scope.resolve();
         if (parent instanceof AST_VarDef) return parent.value === node;
     }
@@ -1164,7 +1165,11 @@ Compressor.prototype.compress = function(node) {
             if (node.extends) node.extends.walk(tw);
             var props = node.properties.filter(function(prop) {
                 reset_flags(prop);
-                if (prop.key instanceof AST_Node) prop.key.walk(tw);
+                if (prop.key instanceof AST_Node) {
+                    tw.push(prop);
+                    prop.key.walk(tw);
+                    tw.pop();
+                }
                 return prop.value;
             });
             if (node.name) {
@@ -1184,6 +1189,7 @@ Compressor.prototype.compress = function(node) {
                 }
             }
             props.forEach(function(prop) {
+                tw.push(prop);
                 if (!prop.static || is_static_field_or_init(prop) && prop.value.contains_this()) {
                     push(tw);
                     prop.value.walk(tw);
@@ -1191,6 +1197,7 @@ Compressor.prototype.compress = function(node) {
                 } else {
                     prop.value.walk(tw);
                 }
+                tw.pop();
             });
             return true;
         });
@@ -12296,7 +12303,7 @@ Compressor.prototype.compress = function(node) {
             var single_use = def.single_use && !(parent instanceof AST_Call && parent.is_expr_pure(compressor));
             if (single_use) {
                 if (is_lambda(fixed)) {
-                    if ((def.scope !== self.scope.resolve() || def.in_loop)
+                    if ((def.scope !== self.scope.resolve(true) || def.in_loop)
                         && (!compressor.option("reduce_funcs") || def.escaped.depth == 1 || fixed.inlined)) {
                         single_use = false;
                     } else if (def.redefined()) {

test/compress/classes.js

@@ -599,6 +599,7 @@ drop_extends: {
         inline: true,
         passes: 2,
         pure_getters: "strict",
+        reduce_funcs: true,
         reduce_vars: true,
         sequences: true,
         side_effects: true,
@@ -921,6 +922,7 @@ single_use_3: {
 
 single_use_4: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -1503,6 +1505,218 @@ keep_instanceof_3: {
     node_version: ">=4"
 }
 
+keep_field_reference_1: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {}
+        class A {
+            p = f;
+        }
+        console.log(new A().p === new A().p ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        function f() {}
+        class A {
+            p = f;
+        }
+        console.log(new A().p === new A().p ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+keep_field_reference_2: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {}
+        var A = class {
+            p = f;
+        };
+        console.log(new A().p === new A().p ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        function f() {}
+        var A = class {
+            p = f;
+        };
+        console.log(new A().p === new A().p ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+keep_field_reference_3: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {}
+        class B {
+            p = A;
+        }
+        console.log(new B().p === new B().p ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        class A {}
+        class B {
+            p = A;
+        }
+        console.log(new B().p === new B().p ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+keep_field_reference_4: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        var A = class {};
+        var B = class {
+            p = A;
+        };
+        console.log(new B().p === new B().p ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        var A = class {};
+        var B = class {
+            p = A;
+        };
+        console.log(new B().p === new B().p ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+keep_static_field_reference_1: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {}
+        class A {
+            static P = f;
+        }
+        console.log(A.P === A.P ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        class A {
+            static P = function() {};
+        }
+        console.log(A.P === A.P ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+keep_static_field_reference_2: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {}
+        var A = class {
+            static P = f;
+        };
+        console.log(A.P === A.P ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        var A = class {
+            static P = function() {};
+        };
+        console.log(A.P === A.P ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+keep_static_field_reference_3: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {}
+        class B {
+            static P = A;
+        }
+        console.log(B.P === B.P ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        class B {
+            static P = class {};
+        }
+        console.log(B.P === B.P ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+keep_static_field_reference_4: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        var A = class {};
+        var B = class {
+            static P = A;
+        };
+        console.log(B.P === B.P ? "PASS" : "FAIL");
+    }
+    expect: {
+        "use strict";
+        var B = class {
+            static P = class {};
+        };
+        console.log(B.P === B.P ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
 issue_805_1: {
     options = {
         inline: true,
@@ -2313,6 +2527,7 @@ issue_4962_1: {
     options = {
         ie: true,
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2344,6 +2559,7 @@ issue_4962_1_strict: {
     options = {
         ie: true,
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2371,6 +2587,7 @@ issue_4962_1_strict_direct: {
     options = {
         ie: true,
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2402,6 +2619,7 @@ issue_4962_2: {
     options = {
         ie: true,
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2433,6 +2651,7 @@ issue_4962_2_strict: {
     options = {
         ie: true,
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2461,6 +2680,7 @@ issue_4962_2_strict_direct: {
     options = {
         ie: true,
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2495,6 +2715,7 @@ issue_4962_2_strict_direct_inline: {
         ie: true,
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2878,6 +3099,7 @@ issue_5053_4: {
 issue_5082_1: {
     options = {
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2910,6 +3132,7 @@ issue_5082_1: {
 issue_5082_1_strict: {
     options = {
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2943,6 +3166,7 @@ issue_5082_2: {
     options = {
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2976,6 +3200,7 @@ issue_5082_2_static: {
     options = {
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }