treat unused parameter as error

Signed-off-by: romintomasetti <romin.tomasetti@gmail.com>

Author: romintomasetti

CMakeLists.txt

@@ -226,7 +226,7 @@ add_library(stdexec_executable_flags INTERFACE)
 
 # Enable warnings
 target_compile_options(stdexec_executable_flags INTERFACE
-                       $<$<STREQUAL:${stdexec_compiler_frontend},GNU>:-Wall>
+                       $<$<STREQUAL:${stdexec_compiler_frontend},GNU>:-Wall,-Werror=unused-parameter>
                        $<$<STREQUAL:${stdexec_compiler_frontend},AppleClang>:-Wall>
                        $<$<STREQUAL:${stdexec_compiler_frontend},MSVC>:/W4>)
 

include/stdexec/__detail/__submit.hpp

@@ -135,7 +135,7 @@ namespace stdexec {
       : __result_(connect(static_cast<_Sender&&>(__sndr), static_cast<_Receiver&&>(__rcvr))) {
     }
 
-    void submit(_Sender&& __sndr, _Receiver&&) noexcept {
+    void submit(_Sender&&, _Receiver&&) noexcept {
       stdexec::start(__result_);
     }