From ec79d7049548b1fc667815599f45ab07bef8b47e Mon Sep 17 00:00:00 2001
From: Sergey Bugaev <bugaevc@gmail.com>
Date: Sat, 24 May 2025 13:22:55 +0300
Subject: [PATCH] parser: Fix statement error recovery

Parser.rollback () can only be used to move *backward* through tokens,
not forward. When we run into a ParseError while parsing a statement,
'begin' points to the start of the statement, and 'e_begin' to the error
location inside the statement. 'rollback (begin)' is then justified,
since we're rolling back to the start of the statement; but moving to
'e_begin' again can not be done with 'rollback (e_begin)'.

Because we failed to seek forward, an syntax error could send us into an
infinite loop. Use Parser.jump () instead, which moves forward through
tokens.

Regession of f5934184d050d1a19f394fdab6f2ee66ff30965f

Fixes https://gitlab.gnome.org/GNOME/vala/issues/1590
---
 tests/Makefile.am                         |  1 +
 tests/parser/try-catch-format-string.test | 10 ++++++++++
 vala/valaparser.vala                      |  7 ++++---
 3 files changed, 15 insertions(+), 3 deletions(-)
 create mode 100644 tests/parser/try-catch-format-string.test

diff --git a/tests/Makefile.am b/tests/Makefile.am
index ce7f030f1..e8e9072e8 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1073,6 +1073,7 @@ TESTS = \
 	parser/switch-section-missing-colon.test \
 	parser/switch-section-outside-switch.test \
 	parser/template.vala \
+	parser/try-catch-format-string.test \
 	parser/try-catch-in-switch-case-invalid.test \
 	parser/tuple.vala \
 	parser/unsupported-property-async.test \
diff --git a/tests/parser/try-catch-format-string.test b/tests/parser/try-catch-format-string.test
new file mode 100644
index 000000000..5bf087315
--- /dev/null
+++ b/tests/parser/try-catch-format-string.test
@@ -0,0 +1,10 @@
+Invalid Code
+
+void main () {
+	try {
+		this.connection = new Gda.Connection.from_string ("", @"DB_DIR=$db_path;DB_NAME=revala", null, Gda.ConnectionOptions.NONE);
+	} catch (GLib.Error as error) {
+		stdout.printf("Error creating the connection to the database");
+		throw error;
+	}
+}
diff --git a/vala/valaparser.vala b/vala/valaparser.vala
index 0f2b1004d..656e25687 100644
--- a/vala/valaparser.vala
+++ b/vala/valaparser.vala
@@ -1738,7 +1738,7 @@ public class Vala.Parser : CodeVisitor {
 			string token = ((EnumClass) typeof (TokenType).class_ref ()).get_value (type).value_nick;
 			rollback (begin);
 			if (!is_expression ()) {
-				rollback (e_begin);
+				jump (e_begin);
 				throw e;
 			}
 			try {
@@ -1746,10 +1746,11 @@ public class Vala.Parser : CodeVisitor {
 				Report.warning (get_src (begin), "`%s' is a syntax keyword, replace with `@%s'", token, token);
 			} catch (ParseError e2) {
 				var e2_begin = get_location ();
-				rollback (e_begin);
+				jump (e_begin);
 				next ();
 				Report.error (get_src (e_begin), "Possible `%s-statement' syntax error, %s", token, e.message);
-				rollback (e2_begin);
+				rollback (begin);
+				jump (e2_begin);
 				throw e2;
 			}
 		}
-- 
2.47.2