compiler: fix another try/catch miscompilation

When skipping over the catch block of a try/catch statement, make sure to
emit the jump after the try scope variables have been popped off the stack
in order to prevent a stack position mismatch between compiler and vm.

Fixes: 9ad9afb ("compiler: fix try/catch miscompilation")
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

2 files changed, 28 insertions, 4 deletions

diff --git a/compiler.c b/compiler.c
index 15c8f8e..1b0d1c4 100644
--- a/compiler.c
+++ b/compiler.c
@@ -2427,14 +2427,14 @@ uc_compiler_compile_try(uc_compiler *compiler)
 	       !uc_compiler_parse_check(compiler, TK_EOF))
 		uc_compiler_compile_declaration(compiler);
 
-	/* jump beyond catch branch */
-	try_to = chunk->count;
-	jmp_off = uc_compiler_emit_jmp(compiler, 0, 0);
-
 	uc_compiler_parse_consume(compiler, TK_RBRACE);
 
 	uc_compiler_leave_scope(compiler);
 
+	/* jump beyond catch branch */
+	try_to = chunk->count;
+	jmp_off = uc_compiler_emit_jmp(compiler, 0, 0);
+
 
 	/* Catch block ---------------------------------------------------------- */
 	if (try_to > try_from) {
diff --git a/tests/03_bugs/01_try_catch_stack_mismatch b/tests/03_bugs/01_try_catch_stack_mismatch
index ae7c760..f6e5a0a 100644
--- a/tests/03_bugs/01_try_catch_stack_mismatch
+++ b/tests/03_bugs/01_try_catch_stack_mismatch
@@ -26,3 +26,27 @@ compiler and vm, causing local variables to yield wrong values at runtime.
 	f()
 %}
 -- End --
+
+
+When compiling a try/catch statement with local variable declearations
+within the try block, the catch skip jump incorrectly happened before the
+local try block variables were popped off the stack, leading to a stack
+position mismatch between compiler and vm, causing local variables to
+yield wrong values at runtime.
+
+-- Expect stdout --
+1
+-- End --
+
+-- Testcase --
+{%
+	try {
+		let a;
+	}
+	catch {}
+
+	let b = 1;
+
+	print(b, "\n");
+%}
+-- End --