Implement `OS::get_locale_language()` helper method

This method extracts the 2 or 3-letter language code from `OS::get_locale()`,
making it easier for users to identify the "main" language code for users
that might have different OS locales due to different OS or region, but
should be matched to the same translation (e.g. "generic" Spanish).

Fixes #40703.

4 files changed, 13 insertions, 0 deletions

diff --git a/core/core_bind.cpp b/core/core_bind.cpp
index 58aecf39aa..e029b85450 100644
--- a/core/core_bind.cpp
+++ b/core/core_bind.cpp
@@ -286,6 +286,10 @@ String OS::get_locale() const {
 	return ::OS::get_singleton()->get_locale();
 }
 
+String OS::get_locale_language() const {
+	return ::OS::get_singleton()->get_locale_language();
+}
+
 String OS::get_model_name() const {
 	return ::OS::get_singleton()->get_model_name();
 }
@@ -547,6 +551,7 @@ void OS::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("delay_usec", "usec"), &OS::delay_usec);
 	ClassDB::bind_method(D_METHOD("delay_msec", "msec"), &OS::delay_msec);
 	ClassDB::bind_method(D_METHOD("get_locale"), &OS::get_locale);
+	ClassDB::bind_method(D_METHOD("get_locale_language"), &OS::get_locale_language);
 	ClassDB::bind_method(D_METHOD("get_model_name"), &OS::get_model_name);
 
 	ClassDB::bind_method(D_METHOD("is_userfs_persistent"), &OS::is_userfs_persistent);
diff --git a/core/core_bind.h b/core/core_bind.h
index 8e95629695..a5d5a7c8ce 100644
--- a/core/core_bind.h
+++ b/core/core_bind.h
@@ -178,6 +178,7 @@ public:
 	Vector<String> get_cmdline_args();
 
 	String get_locale() const;
+	String get_locale_language() const;
 
 	String get_model_name() const;
 
diff --git a/core/os/os.cpp b/core/os/os.cpp
index dc3fe29dca..7505f3ff34 100644
--- a/core/os/os.cpp
+++ b/core/os/os.cpp
@@ -231,6 +231,12 @@ String OS::get_locale() const {
 	return "en";
 }
 
+// Non-virtual helper to extract the 2 or 3-letter language code from
+// `get_locale()` in a way that's consistent for all platforms.
+String OS::get_locale_language() const {
+	return get_locale().left(3).replace("_", "");
+}
+
 // Helper function to ensure that a dir name/path will be valid on the OS
 String OS::get_safe_dir_name(const String &p_dir_name, bool p_allow_dir_separator) const {
 	Vector<String> invalid_chars = String(": * ? \" < > |").split(" ");
diff --git a/core/os/os.h b/core/os/os.h
index f585483300..c027428477 100644
--- a/core/os/os.h
+++ b/core/os/os.h
@@ -243,6 +243,7 @@ public:
 	RenderThreadMode get_render_thread_mode() const { return _render_thread_mode; }
 
 	virtual String get_locale() const;
+	String get_locale_language() const;
 
 	String get_safe_dir_name(const String &p_dir_name, bool p_allow_dir_separator = false) const;
 	virtual String get_godot_dir_name() const;