You get no warning because ELF linkers support symbol interposition.
In your case, the symbol defined by the static library becomes a symbol
defined in the main executable. There is, by default, a single global
namespace of symbols defined in the main executable and in shared
libraries. When the executable and a shared library both define the
same symbol, the one in the executable takes precedence. All references
in the shared library to that symbol become references to the symbol
definition in the executable. This is not an error.
ELF works this way because it means that if the executable defines
"malloc", the shared libc will call the "malloc" defined in the
executable, rather than calling its own malloc. This is considered to
be a feature.
You can adjust this default behaviour in various way, primarily by using
symbol visibility.
Ian
Is there an option on the linker to at least warn me it is doing this?
I understand why it is happening now (thanks!) at least. But I am
worried about this same problem elsewhere. I expect this could happen
to me with 3rd party libraries I use. And unless a crash happens (like
it did in this case with my own libraries), it would be difficult to
diagnose.
- Brian
