[jira] [Commented] (MYNEWT-688) error: ignoring return value of 'write', declared with attribute warn_unused_result

["Jeff Chan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MYNEWT-688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942216#comment-15942216 ] 

Jeff Chan commented on MYNEWT-688:
----------------------------------

+        (void)write(1, msg, sizeof(msg)); <- does not seem to work

----

#pragma works:

+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-result" 
+#pragma GCC diagnostic pop 

---

fake use of return works (but seems bad for performance)

+++ b/kernel/os/src/arch/sim/os_fault.c
+    if (1 == write(1, msg, strlen(msg))) {;};


> error: ignoring return value of 'write', declared with attribute warn_unused_result
> -----------------------------------------------------------------------------------
>
>                 Key: MYNEWT-688
>                 URL: https://issues.apache.org/jira/browse/MYNEWT-688
>             Project: Mynewt
>          Issue Type: Bug
>          Components: HAL
>    Affects Versions: v1_0_0_beta1
>         Environment: OS X w/ newt docker container
>            Reporter: Jeff Chan
>            Assignee: Marko Kiiskila
>            Priority: Minor
>             Fix For: v1_0_0_rel
>
>
> Compile fails for native sim target.  Would love to help, but unsure what the official way to ignore the return value is.  GCC compile flag? Macro that uses and discards the result?
> Error: repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c: In function 'hal_uart_blocking_tx':
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c:317:5: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>      (void) write(uarts[port].u_fd, &data, sizeof(data));
>      ^
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c: In function 'uart_pty':
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c:267:9: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>          write(1, msg, sizeof(msg));
>          ^
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c:276:5: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>      write(1, msg, strlen(msg));
>      ^
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c: In function 'uart_set_attr':
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c:240:9: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>          write(1, msg, sizeof(msg));
>          ^
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c:251:9: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>          write(1, msg, sizeof(msg));
>          ^
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c: In function 'set_nonblock':
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c:223:9: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>          write(1, msg, sizeof(msg));
>          ^
> repos/apache-mynewt-core/hw/mcu/native/src/hal_uart.c:228:9: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>          write(1, msg, sizeof(msg));
>          ^
> Error: repos/apache-mynewt-core/hw/mcu/native/src/hal_system.c: In function 'usage':
> repos/apache-mynewt-core/hw/mcu/native/src/hal_system.c:58:5: error: ignoring return value of 'write', declared with attribute warn_unused_result [-Werror=unused-result]
>      (void) write(2, msg, strlen(msg));
>      ^
> cc1: all warnings being treated as errors



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