Fix minor warning w/Ubuntu18.04 in host test build (esp8266#5829)

earlephilhower · devyte · commit 82da5c76b97e · 2019-03-02T14:37:03.000-03:00
GCC reports the following warning about ignoring the return value of
write() (to the console/UART in this instance).

common/MockUART.cpp: In function ‘void uart_do_write_char(int, char)’:
common/MockUART.cpp:67:8: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
   write(uart_nr + 1, &amp;c, 1);
   ~~~~~^~~~~~~~~~~~~~~~~~~~

Add a simple warning printout to STDERR which may not be the same as the
UART stream and could succeed.
diff --git a/tests/host/common/MockUART.cpp b/tests/host/common/MockUART.cpp
@@ -64,7 +64,8 @@ static void
 uart_do_write_char(const int uart_nr, char c)
 {
 	if (uart_nr >= UART0 && uart_nr <= UART1)
-		write(uart_nr + 1, &c, 1);
+		if (1 != write(uart_nr + 1, &c, 1))
+			fprintf(stderr, "Unable to write character to emulated UART stream: %d\n", c);
 }
 
 // write a new byte into the RX FIFO buffer

Original file line number	Diff line number	Diff line change
`@@ -64,7 +64,8 @@ static void`
`64`	`64`	`uart_do_write_char(const int uart_nr, char c)`
`65`	`65`	`{`
`66`	`66`	`if (uart_nr >= UART0 && uart_nr <= UART1)`
`67`		`- write(uart_nr + 1, &c, 1);`
	`67`	`+ if (1 != write(uart_nr + 1, &c, 1))`
	`68`	`+ fprintf(stderr, "Unable to write character to emulated UART stream: %d\n", c);`
`68`	`69`	`}`
`69`	`70`
`70`	`71`	`// write a new byte into the RX FIFO buffer`