Merge pull request #2165 from svaarala/improve-syntax-error-end-of-input

Improve SyntaxError "end of input" detection

RELEASES.rst

@@ -3562,7 +3562,8 @@ Planned
 
 * Fix some C++ compile warnings (GH-2161)
 
-* Include "end of input" in error message if SyntaxError occurs at end of file (GH-2152)
+* Include "end of input" in error message if SyntaxError occurs at end of
+  file (GH-2152, GH-2165)
 
 3.0.0 (XXXX-XX-XX)
 ------------------

src-input/duk_error_augment.c

@@ -433,11 +433,28 @@ DUK_LOCAL void duk__add_compiler_error_line(duk_hthread *thr) {
 	                     (duk_tval *) duk_get_tval(thr, -1)));
 
 	if (duk_get_prop_stridx_short(thr, -1, DUK_STRIDX_MESSAGE)) {
-                if (thr->compile_ctx->curr_token.start_offset + 1 >= thr->compile_ctx->lex.input_length) {
-			duk_push_sprintf(thr, " (line %ld, end of input)", (long) thr->compile_ctx->curr_token.start_line);
-		} else {
-			duk_push_sprintf(thr, " (line %ld)", (long) thr->compile_ctx->curr_token.start_line);
-		}
+		duk_bool_t at_end;
+
+		/* Best guesstimate that error occurred at end of input, token
+		 * truncated by end of input, etc.
+		 */
+#if 0
+		at_end = (thr->compile_ctx->curr_token.start_offset + 1 >= thr->compile_ctx->lex.input_length);
+		at_end = (thr->compile_ctx->lex.window[0].codepoint < 0 || thr->compile_ctx->lex.window[1].codepoint < 0);
+#endif
+		at_end = (thr->compile_ctx->lex.window[0].codepoint < 0);
+
+		DUK_D(DUK_DPRINT("syntax error, determined at_end=%ld; curr_token.start_offset=%ld, "
+		                 "lex.input_length=%ld, window[0].codepoint=%ld, window[1].codepoint=%ld",
+		                 (long) at_end,
+		                 (long) thr->compile_ctx->curr_token.start_offset,
+		                 (long) thr->compile_ctx->lex.input_length,
+		                 (long) thr->compile_ctx->lex.window[0].codepoint,
+		                 (long) thr->compile_ctx->lex.window[1].codepoint));
+
+		duk_push_sprintf(thr, " (line %ld%s)",
+		                 (long) thr->compile_ctx->curr_token.start_line,
+		                 at_end ? ", end of input" : "");
 		duk_concat(thr, 2);
 		duk_put_prop_stridx_short(thr, -2, DUK_STRIDX_MESSAGE);
 	} else {

tests/ecmascript/test-dev-syntax-error-end-of-input.js

@@ -0,0 +1,48 @@
+/*---
+{
+    "custom": true
+}
+---*/
+
+/*===
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": false
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": true
+ERROR, contains "end of input": false
+SUCCESS: undefined
+SUCCESS: 123
+===*/
+
+[
+    'var x =',
+    'var x =;',
+    'var x =; var y = 1;',  // error not at end of input
+    'var x = 1e',
+    'var x = 1 +',
+    'var x = "',
+    'var x = "foo bar',
+    'var x = { foo: 123',
+    'var x = { foo: 123, ',
+    'var x = { foo: 123, bar',
+    'var x = { foo: 123, bar:',
+    'var x = { foo: 123, bar: 234',
+    'var x = { foo: 123, bar: 234 var z = 1;',  // error not at end of input
+    'var x = { foo: 123, bar: 234 }',  // no error
+    '123'  // no error
+].forEach(function (v) {
+    try {
+        print('SUCCESS: ' + eval(v));
+    } catch (e) {
+        //print(e.message);
+        print('ERROR, contains "end of input": ' + (e.message.indexOf('end of input') >= 0));
+    }
+});