From 37ed9dc95aeeffd5ca570f1be53dbb7e4bf95ef2 Mon Sep 17 00:00:00 2001
From: Jose Mendoza <56417208+StunxFS@users.noreply.github.com>
Date: Wed, 6 Nov 2024 14:00:07 -0400
Subject: [PATCH] cgen: avoid generation of empty `or` blocks for `f() or {}`
 (#22775)

---
 vlib/v/gen/c/cgen.v                                 | 5 +++++
 vlib/v/gen/c/testdata/unused_result_err.c.must_have | 2 ++
 vlib/v/gen/c/testdata/unused_result_err.vv          | 7 +++++++
 3 files changed, 14 insertions(+)
 create mode 100644 vlib/v/gen/c/testdata/unused_result_err.c.must_have
 create mode 100644 vlib/v/gen/c/testdata/unused_result_err.vv

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 52ba0fb97..4ee62deb7 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -7184,6 +7184,11 @@ fn (mut g Gen) gen_or_block_stmts(cvar_name string, cast_typ string, stmts []ast
 // Returns the type of the last stmt
 fn (mut g Gen) or_block(var_name string, or_block ast.OrExpr, return_type ast.Type) {
 	cvar_name := c_name(var_name)
+	if or_block.kind == .block && or_block.stmts.len == 0 {
+		// generate nothing, block is empty
+		g.write(';\n${util.tabs(g.indent)}(void)${cvar_name};')
+		return
+	}
 	mut mr_styp := g.base_type(return_type)
 	is_none_ok := return_type == ast.ovoid_type
 	g.writeln(';')
diff --git a/vlib/v/gen/c/testdata/unused_result_err.c.must_have b/vlib/v/gen/c/testdata/unused_result_err.c.must_have
new file mode 100644
index 000000000..7ac73115d
--- /dev/null
+++ b/vlib/v/gen/c/testdata/unused_result_err.c.must_have
@@ -0,0 +1,2 @@
+_result_void _t1 = main__res();
+(void)_t1;
\ No newline at end of file
diff --git a/vlib/v/gen/c/testdata/unused_result_err.vv b/vlib/v/gen/c/testdata/unused_result_err.vv
new file mode 100644
index 000000000..57071423b
--- /dev/null
+++ b/vlib/v/gen/c/testdata/unused_result_err.vv
@@ -0,0 +1,7 @@
+module main
+
+fn res() ! {}
+
+fn main() {
+	res() or {}
+}
-- 
2.39.5