Here's a minimal test case: -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 --
$ cat test.cpp extern "C" { void f1() { union some_type{ char a[2]; int b; } variable; } void f2() { union some_type{ char a[2]; int b; } variable; } } $ arm-none-eabi-gcc test.cpp -c test.cpp: In function 'void f2()': test.cpp:17:5: warning: conflicting C language linkage declaration 'f2()::some_type variable' } variable; ^~~~~~~~ test.cpp:9:5: note: previous declaration 'f1()::some_type variable' } variable; ^~~~~~~~ $ arm-none-eabi-gcc --version arm-none-eabi-gcc (bleeding-edge-toolchain) 8.0.1 20180427 (prerelease) Copyright (C) 2018 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 -- >8 -- For the problem to appear: - functions with the types and variables have to be extern "C" - the file must be C++ - there has to be both a type and a variable - the variables must have identical names Any idea whether GCC is correct in this case or maybe the error is in the headers? Regards, FCh