Fix if (0);"test"||fail() 2v19 regression - strings after if(0) did…

…n't get interpreted

Ensure eval("1;;;")==1 - eval("1;")==1 before, but not eval("1;;")

We hit this with minification in the AT library... If there's a string right after an if(0) it
doesn't get parsed!

This happens because since 2v19ish we're no longer storing string contents in RAM if
we're not supposed to be executing. But we need to be sure we don't Lex too far ahead
with execute=false set

ChangeLog

@@ -2,6 +2,8 @@
             Bangle.js2: When rendering overlays, *do not* use the current FG/BG color for 1 bit overlays
             nRF52 SDK15: Fix UART when >1 central link enabled
             Bangle.js2: Allow 2 central links at once
+            Fix `if (0);"test"||fail()` 2v19 regression - strings after if(0) didn't get interpreted 
+            Ensure eval("1;;;")==1 - eval("1;")==1 before, but not eval("1;;")            
 
      2v19 : Fix Object.values/entries for numeric keys after 2v18 regression (fix #2375)
             nRF52: for SD>5 use static buffers for advertising and scan response data (#2367)

src/jsparse.c

@@ -2318,7 +2318,6 @@ NO_INLINE JsVar *jspeBlockOrStatement() {
     return 0;
   } else {
     JsVar *v = jspeStatement();
-    if (lex->tk==';') JSP_ASSERT_MATCH(';');
     return v;
   }
 }
@@ -2330,6 +2329,7 @@ NO_INLINE JsVar *jspParse() {
   while (!JSP_SHOULDNT_PARSE && lex->tk != LEX_EOF) {
     jsvUnLock(v);
     v = jspeBlockOrStatement();
+    while (lex->tk==';') JSP_ASSERT_MATCH(';');
     jsvCheckReferenceError(v);
   }
   return v;
@@ -2410,7 +2410,9 @@ NO_INLINE JsVar *jspeStatementIf() {
   JSP_SAVE_EXECUTE();
   if (!cond) jspSetNoExecute();
   JsExecFlags hasError = 0;
-  JsVar *a = jspeBlockOrStatement();
+  JsVar *a = 0;
+  if (lex->tk!=';')
+    a = jspeBlockOrStatement();
   hasError |= execInfo.execute&EXEC_ERROR_MASK;
   if (!cond) {
     jsvUnLock(a);
@@ -2419,11 +2421,16 @@ NO_INLINE JsVar *jspeStatementIf() {
   } else {
     result = a;
   }
+  /* We must manually parse ';' here, because if we did it when execInfo.execute==false (eg `if(0);`)
+  then if a String comes straight after it wouldn't have been interpreted */
+  if (lex->tk==';') JSP_ASSERT_MATCH(';');
   if (lex->tk==LEX_R_ELSE) {
     JSP_ASSERT_MATCH(LEX_R_ELSE);
     JSP_SAVE_EXECUTE();
     if (cond) jspSetNoExecute();
-    JsVar *a = jspeBlockOrStatement();
+    JsVar *a = 0;
+    if (lex->tk!=';')
+      a = jspeBlockOrStatement();
     hasError |= execInfo.execute&EXEC_ERROR_MASK;
     if (cond) {
       jsvUnLock(a);

tests/test_string_noparse.js

@@ -0,0 +1,20 @@
+function fail(n) {
+  throw new Error("FAILED at "+n);
+}
+
+/* We hit this with minification in the AT library... If there's a string right after an if(0) it
+doesn't get parsed! 
+
+This happens because since 2v19ish we're no longer storing string contents in RAM if
+we're not supposed to be executing. But we need to be sure we don't Lex too far ahead
+with execute=false set
+*/
+
+while (0) 1;"test"||fail("while") // ok
+for (;0;);"test"||fail("for")     // ok
+if (1) 1;"test"||fail("if(1)1;")   // ok
+if (0) 1;"test"||fail("if(0)1;")   // failed
+if (0);"test"||fail("if(0);")      // failed
+if (1);else;"test"||fail("if(1);else;") // failed
+// if we got here we're ok
+result=1