fix: Restrict leading zero before decimal separator (#1389)

Author: MaxGraey

src/tokenizer.ts

@@ -1052,13 +1052,15 @@ export class Tokenizer extends DiagnosticEmitter {
 
   readIdentifier(): string {
     var text = this.source.text;
-    var start = this.pos;
     var end = this.end;
+    var pos = this.pos;
+    var start = pos;
     while (
-      ++this.pos < end &&
-      isIdentifierPart(text.charCodeAt(this.pos))
+      ++pos < end &&
+      isIdentifierPart(text.charCodeAt(pos))
     );
-    return text.substring(start, this.pos);
+    this.pos = pos;
+    return text.substring(start, pos);
   }
 
   readString(): string {
@@ -1362,6 +1364,11 @@ export class Tokenizer extends DiagnosticEmitter {
               : DiagnosticCode.Multiple_consecutive_numeric_separators_are_not_permitted,
             this.range(pos)
           );
+        } else if (pos - 1 == start && text.charCodeAt(pos - 1) == CharCode._0) {
+          this.error(
+            DiagnosticCode.Numeric_separators_are_not_allowed_here,
+            this.range(pos)
+          );
         }
         sepEnd = pos + 1;
       } else {
@@ -1497,9 +1504,7 @@ export class Tokenizer extends DiagnosticEmitter {
     var text = this.source.text;
     var end = this.end;
     var start = this.pos;
-    var sepCount = 0;
-
-    sepCount += this.readDecimalFloatPartial(false);
+    var sepCount = this.readDecimalFloatPartial(false);
     if (this.pos < end && text.charCodeAt(this.pos) == CharCode.DOT) {
       ++this.pos;
       sepCount += this.readDecimalFloatPartial();
@@ -1518,7 +1523,7 @@ export class Tokenizer extends DiagnosticEmitter {
       }
     }
     let result = text.substring(start, this.pos);
-    if (sepCount > 0) result = result.replaceAll("_", "");
+    if (sepCount) result = result.replaceAll("_", "");
     return parseFloat(result);
   }
 
@@ -1553,7 +1558,6 @@ export class Tokenizer extends DiagnosticEmitter {
       } else if (!isDecimalDigit(c)) {
         break;
       }
-
       ++pos;
     }
 

tests/parser/numeric-separators.ts

@@ -35,6 +35,13 @@
 1e2_; // 6188
 1e-1__0; // 6189
 
+0_0; // 6188
 0_0.0; // 6188
 0_0.0_0; // 6188
-0_0e0_0; // 6188
+0_0e0_0; // 6188
+
+0x_11_11; // 6188
+0o_11_11; // 6188
+0b_11_11; // 6188
+
+00_01 // 1121

tests/parser/numeric-separators.ts.fixture.ts

@@ -28,6 +28,11 @@
 0;
 0;
 0;
+0;
+4369;
+585;
+15;
+1;
 // ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(14,9+0)
 // ERROR 6189: "Multiple consecutive numeric separators are not permitted." in numeric-separators.ts(15,4+0)
 // ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(17,11+0)
@@ -48,3 +53,8 @@
 // ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(38,2+0)
 // ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(39,2+0)
 // ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(40,2+0)
+// ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(41,2+0)
+// ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(43,3+0)
+// ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(44,3+0)
+// ERROR 6188: "Numeric separators are not allowed here." in numeric-separators.ts(45,3+0)
+// ERROR 1121: "Octal literals are not allowed in strict mode." in numeric-separators.ts(47,1+5)