fix corner case in evaluate (#3559)

fixes #3558
mishoo · Oct 31, 2019 · 1e9b576 · 1e9b576
1 parent 3797458
commit 1e9b576
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Showing 2 changed files with 25 additions and 4 deletions.
diff --git a/lib/compress.js b/lib/compress.js
@@ -2862,10 +2862,10 @@ merge(Compressor.prototype, {
               case "+": return +v;
               case "++":
               case "--":
-                if (e instanceof AST_SymbolRef) {
-                    var refs = e.definition().references;
-                    if (refs[refs.length - 1] === e) return v;
-                }
+                if (!(e instanceof AST_SymbolRef)) return this;
+                var refs = e.definition().references;
+                if (refs[refs.length - 1] !== e) return this;
+                return HOP(e, "_eval") ? +(this.operator[0] + 1) + +v : v;
             }
             return this;
         });

diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
@@ -1838,3 +1838,24 @@ recursive_function_2: {
     }
     expect_stdout: "120"
 }
+
+issue_3558: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        function f(a) {
+            return 1 + --a;
+        }
+        console.log(f(true), f(false));
+    }
+    expect: {
+        function f(a) {
+            return 1 + --a;
+        }
+        console.log(1, 0);
+    }
+    expect_stdout: "1 0"
+}