Improved serial write_str implementation to properly handle errors

Signed-off-by: Daniel Egger <daniel@eggers-club.de>

Author: therealprof

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Updated to stm32-rs v0.6.0 - @HarkonenBade
 - Updated the ADC code to use variants added in stm32-rs v0.6.0 - @HarkonenBade
+- Improved serial `write_str` implementation
 
 ## [v0.12.0] - 2019-01-13
 

src/serial.rs

@@ -518,10 +518,10 @@ where
     Tx<USART>: embedded_hal::serial::Write<u8>,
 {
     fn write_str(&mut self, s: &str) -> Result {
-        use nb::block;
-
-        let _ = s.as_bytes().iter().map(|c| block!(self.write(*c))).last();
-        Ok(())
+        s.as_bytes()
+            .iter()
+            .try_for_each(|c| nb::block!(self.write(*c)))
+            .map_err(|_| core::fmt::Error)
     }
 }
 
@@ -531,10 +531,10 @@ where
     TXPIN: TxPin<USART>,
 {
     fn write_str(&mut self, s: &str) -> Result {
-        use nb::block;
-
-        let _ = s.as_bytes().iter().map(|c| block!(self.write(*c))).last();
-        Ok(())
+        s.as_bytes()
+            .iter()
+            .try_for_each(|c| nb::block!(self.write(*c)))
+            .map_err(|_| core::fmt::Error)
     }
 }