From a58f980b02f526b50b2d3fff4764bd7b83514bf0 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 4 Mar 2024 18:15:28 +0200
Subject: [PATCH] os: workaround a `-prod -cc gcc` bug, affecting os.open_file
 (fix #20923) (related to #20872) (#20960)

---
 vlib/builtin/string.v                            |  2 +-
 vlib/os/file.c.v                                 |  1 +
 vlib/v/gen/c/testdata/self_printer_with_prod.out | 15 +++++++++++++++
 vlib/v/gen/c/testdata/self_printer_with_prod.vv  | 15 +++++++++++++++
 4 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/gen/c/testdata/self_printer_with_prod.out
 create mode 100644 vlib/v/gen/c/testdata/self_printer_with_prod.vv

diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index e0ccfa33b8..3f835ff75f 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -315,7 +315,7 @@ fn (a string) clone_static() string {
 
 // clone returns a copy of the V string `a`.
 pub fn (a string) clone() string {
-	if a.len == 0 {
+	if a.len <= 0 {
 		return ''
 	}
 	mut b := string{
diff --git a/vlib/os/file.c.v b/vlib/os/file.c.v
index cb3d1e235c..6108974fe4 100644
--- a/vlib/os/file.c.v
+++ b/vlib/os/file.c.v
@@ -47,6 +47,7 @@ fn fix_windows_path(path string) string {
 }
 
 // open_file tries to open or create a file with custom flags and permissions.
+@[noinline]
 pub fn open_file(path string, mode string, options ...int) !File {
 	mut flags := 0
 	mut seek_to_end := false
diff --git a/vlib/v/gen/c/testdata/self_printer_with_prod.out b/vlib/v/gen/c/testdata/self_printer_with_prod.out
new file mode 100644
index 0000000000..dfe042d4a8
--- /dev/null
+++ b/vlib/v/gen/c/testdata/self_printer_with_prod.out
@@ -0,0 +1,15 @@
+// vtest vflags: -prod -skip-unused
+// See https://github.com/vlang/v/issues/20923
+module main
+
+import os
+import io
+
+fn main() {
+	mut file := os.open_file(@FILE, 'r')!
+	mut buff_reader := io.new_buffered_reader(reader: file)
+	for {
+		a := buff_reader.read_line() or { break }
+		println(a)
+	}
+}
diff --git a/vlib/v/gen/c/testdata/self_printer_with_prod.vv b/vlib/v/gen/c/testdata/self_printer_with_prod.vv
new file mode 100644
index 0000000000..dfe042d4a8
--- /dev/null
+++ b/vlib/v/gen/c/testdata/self_printer_with_prod.vv
@@ -0,0 +1,15 @@
+// vtest vflags: -prod -skip-unused
+// See https://github.com/vlang/v/issues/20923
+module main
+
+import os
+import io
+
+fn main() {
+	mut file := os.open_file(@FILE, 'r')!
+	mut buff_reader := io.new_buffered_reader(reader: file)
+	for {
+		a := buff_reader.read_line() or { break }
+		println(a)
+	}
+}