feat(es/minifier): Allow expr_simplifier to do arithmetic with stri…

…ng literals (#8683)

**Description:**
This PR implements the feature described for the issue in #8682.


**Related issue:**

 - Closes #8682.

crates/swc/tests/tsc-references/enumConstantMemberWithString.2.minified.js

@@ -1,3 +1,3 @@
 //// [enumConstantMemberWithString.ts]
 var T1, T2, T3, T4, T5, T11, T21, T31;
-(T11 = T1 || (T1 = {})).a = "1", T11.b = "12", T11.c = "123", T11[T11.d = "a" - "a"] = "d", T11.e = "a1", (T21 = T2 || (T2 = {})).a = "1", T21.b = "12", (T31 = T3 || (T3 = {})).a = "1", T31.b = "12", T31[T31.c = 1] = "c", T31[T31.d = 3] = "d", (T4 || (T4 = {})).a = "1", (T5 || (T5 = {})).a = "12";
+(T11 = T1 || (T1 = {})).a = "1", T11.b = "12", T11.c = "123", T11[T11.d = NaN] = "d", T11.e = "a1", (T21 = T2 || (T2 = {})).a = "1", T21.b = "12", (T31 = T3 || (T3 = {})).a = "1", T31.b = "12", T31[T31.c = 1] = "c", T31[T31.d = 3] = "d", (T4 || (T4 = {})).a = "1", (T5 || (T5 = {})).a = "12";

crates/swc_ecma_transforms_optimization/src/simplify/expr/mod.rs

@@ -896,8 +896,9 @@ impl SimplifyExpr {
         );
 
         if (lv.is_unknown() && rv.is_unknown())
-            || !left.get_type().casted_to_number_on_add()
-            || !right.get_type().casted_to_number_on_add()
+            || op == op!(bin, "+")
+                && (!left.get_type().casted_to_number_on_add()
+                    || !right.get_type().casted_to_number_on_add())
         {
             return Unknown;
         }

crates/swc_ecma_transforms_optimization/src/simplify/expr/tests.rs

@@ -1314,6 +1314,33 @@ fn test_fold_literals_as_numbers() {
     fold("x/false", "x/0"); // should we add an error check? :)
 }
 
+#[test]
+fn test_fold_arithmetic_with_strings() {
+    // Left side of expression is a string
+    fold("'10' - 5", "5");
+    fold("'4' / 2", "2");
+    fold("'11' % 2", "1");
+    fold("'10' ** 2", "100");
+    fold("'Infinity' * 2", "Infinity");
+    fold("'NaN' * 2", "NaN");
+
+    // Right side of expression is a string
+    fold("10 - '5'", "5");
+    fold("4 / '2'", "2");
+    fold("11 % '2'", "1");
+    fold("10 ** '2'", "100");
+    fold("2 * 'Infinity'", "Infinity");
+    fold("2 * 'NaN'", "NaN");
+
+    // Both sides are strings
+    fold("'10' - '5'", "5");
+    fold("'4' / '2'", "2");
+    fold("'11' % '2'", "1");
+    fold("'10' ** '2'", "100");
+    fold("'Infinity' * '2'", "Infinity");
+    fold("'NaN' * '2'", "NaN");
+}
+
 #[test]
 fn test_not_fold_back_to_true_false() {
     fold("!0", "!0");