fix corner cases in side_effects (#5293)

fixes #5292

lib/compress.js

@@ -5399,7 +5399,7 @@ Compressor.prototype.compress = function(node) {
             return any(this.properties, compressor);
         });
         def(AST_Dot, function(compressor) {
-            return !this.optional && this.expression.may_throw_on_access(compressor)
+            return this.expression.may_throw_on_access(compressor)
                 || this.expression.has_side_effects(compressor);
         });
         def(AST_EmptyStatement, return_false);
@@ -5430,7 +5430,7 @@ Compressor.prototype.compress = function(node) {
             return this.body.has_side_effects(compressor);
         });
         def(AST_Sub, function(compressor) {
-            return !this.optional && this.expression.may_throw_on_access(compressor)
+            return this.expression.may_throw_on_access(compressor)
                 || this.expression.has_side_effects(compressor)
                 || this.property.has_side_effects(compressor);
         });
@@ -8370,7 +8370,7 @@ Compressor.prototype.compress = function(node) {
         });
         def(AST_Dot, function(compressor, first_in_statement) {
             var expr = this.expression;
-            if (!this.optional && expr.may_throw_on_access(compressor)) return this;
+            if (expr.may_throw_on_access(compressor)) return this;
             return expr.drop_side_effect_free(compressor, first_in_statement);
         });
         def(AST_Function, function(compressor) {
@@ -8429,17 +8429,8 @@ Compressor.prototype.compress = function(node) {
         });
         def(AST_Sub, function(compressor, first_in_statement) {
             var expr = this.expression;
+            if (expr.may_throw_on_access(compressor)) return this;
             var prop = this.property;
-            if (expr.may_throw_on_access(compressor)) {
-                if (!this.optional) return this;
-                if (prop.has_side_effects(compressor)) {
-                    prop = prop.drop_side_effect_free(compressor);
-                    if (!prop) return expr.drop_side_effect_free(compressor, first_in_statement);
-                    var node = this.clone();
-                    node.property = prop;
-                    return node;
-                }
-            }
             expr = expr.drop_side_effect_free(compressor, first_in_statement);
             if (!expr) return prop.drop_side_effect_free(compressor, first_in_statement);
             prop = prop.drop_side_effect_free(compressor);

test/compress/optional-chains.js

@@ -361,7 +361,9 @@ issue_4906: {
         } while (console.log("PASS"));
     }
     expect: {
-        do {} while (console.log("PASS"));
+        do {
+            var a = a?.[42];
+        } while (console.log("PASS"));
     }
     expect_stdout: "PASS"
     node_version: ">=14"
@@ -434,7 +436,7 @@ issue_5039: {
         console.log("PASS");
     }
     expect: {
-        (function f() {});
+        var a = a?.[function f() {}];
         console.log("PASS");
     }
     expect_stdout: "PASS"
@@ -466,3 +468,152 @@ issue_5091: {
     expect_stdout: "PASS"
     node_version: ">=14"
 }
+
+issue_5292_dot: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_5292_dot_pure_getters: {
+    options = {
+        pure_getters: true,
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+    }
+}
+
+issue_5292_dot_pure_getters_strict: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_5292_sub: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+    node_version: ">=14"
+}
+
+issue_5292_sub_pure_getters: {
+    options = {
+        pure_getters: true,
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        console.log("bar");
+    }
+}
+
+issue_5292_sub_pure_getters_strict: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+    node_version: ">=14"
+}