[lwip-devel] [task #16283] LwIP 2.1.3 with mbedTLS 2.28.1 generates 3 warnings with `gcc -std=gnu11 -Wall` (GCC 10)

[Jonathan D]

URL:
  <https://savannah.nongnu.org/task/?16283>

                 Summary: LwIP 2.1.3 with mbedTLS 2.28.1 generates 3 warnings
with `gcc -std=gnu11 -Wall` (GCC 10)
                 Project: lwIP - A Lightweight TCP/IP stack
               Submitter: jona
               Submitted: Tue 15 Nov 2022 10:50:09 AM UTC
                Category: None
         Should Start On: Tue 15 Nov 2022 12:00:00 AM UTC
   Should be Finished on: Tue 15 Nov 2022 12:00:00 AM UTC
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
                  Effort: 0.00


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Follow-up Comments:


-------------------------------------------------------
Date: Tue 15 Nov 2022 10:50:09 AM UTC By: Jonathan D <jona>
Hello,

After having upgrade mbedTLS from 2.28.0 to 2.28.1, GCC generates 3 warnings:

Description     Resource        Path    Location        Type
ignoring return value of 'mbedtls_ssl_flush_output' declared with attribute
'warn_unused_result'
[-Wunused-result]       altcp_tls_mbedtls.c     
/SV-H743/LwIP/src/apps/altcp_tls        line
522     C/C++ Problem
ignoring return value of 'mbedtls_ssl_flush_output' declared with attribute
'warn_unused_result'
[-Wunused-result]       altcp_tls_mbedtls.c     
/SV-H743/LwIP/src/apps/altcp_tls        line
546     C/C++ Problem
ignoring return value of 'mbedtls_ssl_flush_output' declared with attribute
'warn_unused_result'
[-Wunused-result]       altcp_tls_mbedtls.c     
/SV-H743/LwIP/src/apps/altcp_tls        line
1209    C/C++ Problem

The `__warn_unused_result__` was introduced in mbedTLS 2.28.1 for
`mbedtls_ssl_flush_output`. This attribute was not there in mbedTLS 2.28.0.

A patch doesn't seem obvious to me.

Best regards







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