Warn rather than panic on unknown namespace prefix

When a #defined token was used before a namespace, like so (#1676):

    #define nssv_inline_ns inline
    nssv_inline_ns namespace literals {}

bindgen would crash when encountering the unknown token preceding the
namespace token. This is because we don't get to see "past" the ifdef to
the underlying token. The true fix to this is to find a way to extract
ifdef info through clang, but for the time being we simply change the
panic into a warning when such a token is encountered, and then proceed
as if it were empty.

Fixes #1676.

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/headers/issue-1676-macro-namespace-prefix.hpp b/tests/headers/issue-1676-macro-namespace-prefix.hpp
new file mode 100644
index 00000000..297927b6
--- /dev/null
+++ b/tests/headers/issue-1676-macro-namespace-prefix.hpp
@@ -0,0 +1,2 @@
+#define nssv_inline_ns inline
+nssv_inline_ns namespace literals {}