libdrgn: enable -Wmissing-prototypes

This requires workarounds for the Python module initialization function
and the test function exports.

Signed-off-by: Omar Sandoval <osandov@osandov.com>

libdrgn/configure.ac

@@ -111,6 +111,7 @@ AS_IF([test "x$enable_compiler_warnings" != xno],
        -Wformat-overflow=2 dnl
        -Wformat-truncation=2 dnl
        -Wimplicit-fallthrough dnl
+       -Wmissing-prototypes dnl
        -Wvla dnl
        ], [WARN_CFLAGS], [$compiler_flags_test])])
 AS_IF([test "x$enable_compiler_warnings" = xerror],

libdrgn/python/main.c

@@ -220,6 +220,7 @@ static int add_type_aliases(PyObject *m)
        return 0;
 }
 
+PyMODINIT_FUNC PyInit__drgn(void); // Silence -Wmissing-prototypes.
 DRGNPY_PUBLIC PyMODINIT_FUNC PyInit__drgn(void)
 {
 	PyObject *m = PyModule_Create(&drgnmodule);

libdrgn/python/test.c

@@ -5,8 +5,10 @@
  * Wrapper functions for testing.
  *
  * In order to test a few internal interfaces that don't have Python bindings,
- * we export some wrappers for those interfaces and for some required
- * libelf/libdw helpers. These wrappers are accessed via ctypes.
+ * we export some wrappers for those interfaces. These wrappers are accessed via
+ * ctypes.
+ *
+ * The extra declarations are needed to silence -Wmissing-prototypes.
  */
 
 #include "drgnpy.h"
@@ -14,35 +16,42 @@
 #include "../path.h"
 #include "../serialize.h"
 
+typeof(drgn_lexer_init) drgn_test_lexer_init;
 DRGNPY_PUBLIC void drgn_test_lexer_init(struct drgn_lexer *lexer,
 					drgn_lexer_func func, const char *str)
 {
 	return drgn_lexer_init(lexer, func, str);
 }
 
+typeof(drgn_lexer_deinit) drgn_test_lexer_deinit;
 DRGNPY_PUBLIC void drgn_test_lexer_deinit(struct drgn_lexer *lexer)
 {
 	return drgn_lexer_deinit(lexer);
 }
 
+typeof(drgn_lexer_pop) drgn_test_lexer_pop;
 DRGNPY_PUBLIC struct drgn_error *drgn_test_lexer_pop(struct drgn_lexer *lexer,
 						     struct drgn_token *token)
 {
 	return drgn_lexer_pop(lexer, token);
 }
 
+typeof(drgn_lexer_push) drgn_test_lexer_push;
 DRGNPY_PUBLIC struct drgn_error *
 drgn_test_lexer_push(struct drgn_lexer *lexer, const struct drgn_token *token)
 {
 	return drgn_lexer_push(lexer, token);
 }
 
+typeof(drgn_lexer_peek) drgn_test_lexer_peek;
 DRGNPY_PUBLIC struct drgn_error *drgn_test_lexer_peek(struct drgn_lexer *lexer,
 						      struct drgn_token *token)
 {
 	return drgn_lexer_peek(lexer, token);
 }
 
+struct drgn_error *drgn_test_lexer_func(struct drgn_lexer *lexer,
+					struct drgn_token *token);
 DRGNPY_PUBLIC struct drgn_error *drgn_test_lexer_func(struct drgn_lexer *lexer,
 						      struct drgn_token *token)
 {
@@ -57,12 +66,14 @@ DRGNPY_PUBLIC struct drgn_error *drgn_test_lexer_func(struct drgn_lexer *lexer,
 	return NULL;
 }
 
+typeof(drgn_c_family_lexer_func) drgn_test_lexer_c;
 DRGNPY_PUBLIC struct drgn_error *drgn_test_lexer_c(struct drgn_lexer *lexer,
 						   struct drgn_token *token)
 {
 	return drgn_c_family_lexer_func(lexer, token);
 }
 
+typeof(path_iterator_next) drgn_test_path_iterator_next;
 DRGNPY_PUBLIC bool drgn_test_path_iterator_next(struct path_iterator *it,
 						const char **component,
 						size_t *component_len)
@@ -70,12 +81,14 @@ DRGNPY_PUBLIC bool drgn_test_path_iterator_next(struct path_iterator *it,
 	return path_iterator_next(it, component, component_len);
 }
 
+typeof(path_ends_with) drgn_test_path_ends_with;
 DRGNPY_PUBLIC bool drgn_test_path_ends_with(struct path_iterator *haystack,
 					    struct path_iterator *needle)
 {
 	return path_ends_with(haystack, needle);
 }
 
+typeof(serialize_bits) drgn_test_serialize_bits;
 DRGNPY_PUBLIC void drgn_test_serialize_bits(void *buf, uint64_t bit_offset,
 					    uint64_t uvalue, uint8_t bit_size,
 					    bool little_endian)
@@ -83,6 +96,7 @@ DRGNPY_PUBLIC void drgn_test_serialize_bits(void *buf, uint64_t bit_offset,
 	return serialize_bits(buf, bit_offset, uvalue, bit_size, little_endian);
 }
 
+typeof(deserialize_bits) drgn_test_deserialize_bits;
 DRGNPY_PUBLIC uint64_t drgn_test_deserialize_bits(const void *buf,
 						  uint64_t bit_offset,
 						  uint8_t bit_size,