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