x11: logging in Application::get_locale (#1876)

thanks @ColinPitrat

#1870 (comment)

Also changed the name and made it a function

CHANGELOG.md

@@ -111,6 +111,7 @@ You can find its changes [documented below](#070---2021-01-01).
 - Updated to x11rb 0.8.0. ([#1519] by [@psychon])
 - Updated fluent-bundle to 0.15.1 and fluent syntax to 0.11.0 ([#1772] by [@r-ml])
 - Updated usvg to 0.14.1 ([#1802] by [@r-ml])
+- x11: Add logging to `Application::get_locale` ([#1876] by [@Maan2003])
 
 ### Outside News
 
@@ -761,6 +762,7 @@ Last release without a changelog :(
 [#1867]: https://github.com/linebender/druid/pull/1867
 [#1868]: https://github.com/linebender/druid/pull/1868
 [#1873]: https://github.com/linebender/druid/pull/1873
+[#1876]: https://github.com/linebender/druid/pull/1876
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.7.0...master
 [0.7.0]: https://github.com/linebender/druid/compare/v0.6.0...v0.7.0

druid-shell/src/backend/x11/application.rs

@@ -770,21 +770,36 @@ impl Application {
     }
 
     pub fn get_locale() -> String {
-        let var_non_empty = |var| match std::env::var(var) {
-            Ok(s) if s.is_empty() => None,
-            Ok(s) => Some(s),
-            Err(_) => None,
-        };
+        fn locale_env_var(var: &str) -> Option<String> {
+            match std::env::var(var) {
+                Ok(s) if s.is_empty() => {
+                    tracing::debug!("locale: ignoring empty env var {}", var);
+                    None
+                }
+                Ok(s) => {
+                    tracing::debug!("locale: env var {} found: {:?}", var, &s);
+                    Some(s)
+                }
+                Err(std::env::VarError::NotPresent) => {
+                    tracing::debug!("locale: env var {} not found", var);
+                    None
+                }
+                Err(std::env::VarError::NotUnicode(_)) => {
+                    tracing::debug!("locale: ignoring invalid unicode env var {}", var);
+                    None
+                }
+            }
+        }
 
         // from gettext manual
         // https://www.gnu.org/software/gettext/manual/html_node/Locale-Environment-Variables.html#Locale-Environment-Variables
-        let mut locale = var_non_empty("LANGUAGE")
+        let mut locale = locale_env_var("LANGUAGE")
             // the LANGUAGE value is priority list seperated by :
             // See: https://www.gnu.org/software/gettext/manual/html_node/The-LANGUAGE-variable.html#The-LANGUAGE-variable
             .and_then(|locale| locale.split(':').next().map(String::from))
-            .or_else(|| var_non_empty("LC_ALL"))
-            .or_else(|| var_non_empty("LC_MESSAGES"))
-            .or_else(|| var_non_empty("LANG"))
+            .or_else(|| locale_env_var("LC_ALL"))
+            .or_else(|| locale_env_var("LC_MESSAGES"))
+            .or_else(|| locale_env_var("LANG"))
             .unwrap_or_else(|| "en-US".to_string());
 
         // This is done because the locale parsing library we use expects an unicode locale, but these vars have an ISO locale