Add explicit int return type declarations on FFI lambdas.

Sun Studio gives a strange warning about this. This probably doesn't
help actually compile under Sun Studio. But it doesn't hurt to be
explicit.

13 files changed, 53 insertions, 53 deletions

diff --git a/src/lib/ffi/ffi.cpp b/src/lib/ffi/ffi.cpp
index 00181dbc9..39749c4d4 100644
--- a/src/lib/ffi/ffi.cpp
+++ b/src/lib/ffi/ffi.cpp
@@ -81,7 +81,7 @@ int botan_scrub_mem(void* mem, size_t bytes)
 
 int botan_hex_encode(const uint8_t* in, size_t len, char* out, uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const bool uppercase = (flags & BOTAN_FFI_HEX_LOWER_CASE) == 0;
       Botan::hex_encode(out, in, len, uppercase);
       return BOTAN_FFI_SUCCESS;
@@ -90,7 +90,7 @@ int botan_hex_encode(const uint8_t* in, size_t len, char* out, uint32_t flags)
 
 int botan_hex_decode(const char* hex_str, size_t in_len, uint8_t* out, size_t* out_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const std::vector<uint8_t> bin = Botan::hex_decode(hex_str, in_len);
       return Botan_FFI::write_vec_output(out, out_len, bin);
       });
@@ -98,7 +98,7 @@ int botan_hex_decode(const char* hex_str, size_t in_len, uint8_t* out, size_t* o
 
 int botan_base64_encode(const uint8_t* in, size_t len, char* out, size_t* out_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const std::string base64 = Botan::base64_encode(in, len);
       return Botan_FFI::write_str_output(out, out_len, base64);
       });
@@ -107,7 +107,7 @@ int botan_base64_encode(const uint8_t* in, size_t len, char* out, size_t* out_le
 int botan_base64_decode(const char* base64_str, size_t in_len,
                         uint8_t* out, size_t* out_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(*out_len < Botan::base64_decode_max_output(in_len))
          {
          *out_len = Botan::base64_decode_max_output(in_len);
diff --git a/src/lib/ffi/ffi_block.cpp b/src/lib/ffi/ffi_block.cpp
index eae375e63..f3648430a 100644
--- a/src/lib/ffi/ffi_block.cpp
+++ b/src/lib/ffi/ffi_block.cpp
@@ -16,7 +16,7 @@ BOTAN_FFI_DECLARE_STRUCT(botan_block_cipher_struct, Botan::BlockCipher, 0x64C297
 
 int botan_block_cipher_init(botan_block_cipher_t* bc, const char* bc_name)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(bc == nullptr || bc_name == nullptr || *bc_name == 0)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
diff --git a/src/lib/ffi/ffi_cert.cpp b/src/lib/ffi/ffi_cert.cpp
index 17b78cc7c..6031d02aa 100644
--- a/src/lib/ffi/ffi_cert.cpp
+++ b/src/lib/ffi/ffi_cert.cpp
@@ -18,7 +18,7 @@ BOTAN_FFI_DECLARE_STRUCT(botan_x509_cert_struct, Botan::X509_Certificate, 0x8F62
 
 int botan_x509_cert_load_file(botan_x509_cert_t* cert_obj, const char* cert_path)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(!cert_obj || !cert_path)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
@@ -34,7 +34,7 @@ int botan_x509_cert_load_file(botan_x509_cert_t* cert_obj, const char* cert_path
 
 int botan_x509_cert_load(botan_x509_cert_t* cert_obj, const uint8_t cert_bits[], size_t cert_bits_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(!cert_obj || !cert_bits)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
@@ -48,7 +48,7 @@ int botan_x509_cert_load(botan_x509_cert_t* cert_obj, const uint8_t cert_bits[],
 
 int botan_x509_cert_get_public_key(botan_x509_cert_t cert, botan_pubkey_t* key)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(key == nullptr)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
diff --git a/src/lib/ffi/ffi_cipher.cpp b/src/lib/ffi/ffi_cipher.cpp
index 23e277166..ff73de6fb 100644
--- a/src/lib/ffi/ffi_cipher.cpp
+++ b/src/lib/ffi/ffi_cipher.cpp
@@ -20,7 +20,7 @@ struct botan_cipher_struct final : public botan_struct<Botan::Cipher_Mode, 0xB4A
 
 int botan_cipher_init(botan_cipher_t* cipher, const char* cipher_name, uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const bool encrypt_p = ((flags & BOTAN_CIPHER_INIT_FLAG_MASK_DIRECTION) == BOTAN_CIPHER_INIT_FLAG_ENCRYPT);
       const Botan::Cipher_Dir dir = encrypt_p ? Botan::ENCRYPTION : Botan::DECRYPTION;
       std::unique_ptr<Botan::Cipher_Mode> mode(Botan::get_cipher_mode(cipher_name, dir));
@@ -60,7 +60,7 @@ int botan_cipher_set_key(botan_cipher_t cipher,
 int botan_cipher_start(botan_cipher_t cipher_obj,
                        const uint8_t* nonce, size_t nonce_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::Cipher_Mode& cipher = safe_get(cipher_obj);
       cipher.start(nonce, nonce_len);
       cipher_obj->m_buf.reserve(cipher.update_granularity());
@@ -77,7 +77,7 @@ int botan_cipher_update(botan_cipher_t cipher_obj,
                         size_t orig_input_size,
                         size_t* input_consumed)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
 
       size_t input_size = orig_input_size;
       size_t output_size = orig_output_size;
diff --git a/src/lib/ffi/ffi_hash.cpp b/src/lib/ffi/ffi_hash.cpp
index 58fb1d38f..b5f9451d7 100644
--- a/src/lib/ffi/ffi_hash.cpp
+++ b/src/lib/ffi/ffi_hash.cpp
@@ -16,7 +16,7 @@ BOTAN_FFI_DECLARE_STRUCT(botan_hash_struct, Botan::HashFunction, 0x1F0A4F84);
 
 int botan_hash_init(botan_hash_t* hash, const char* hash_name, uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(hash == nullptr || hash_name == nullptr || *hash_name == 0)
          return BOTAN_FFI_ERROR_NULL_POINTER;
       if(flags != 0)
diff --git a/src/lib/ffi/ffi_kdf.cpp b/src/lib/ffi/ffi_kdf.cpp
index cff76237f..8a0ba9be4 100644
--- a/src/lib/ffi/ffi_kdf.cpp
+++ b/src/lib/ffi/ffi_kdf.cpp
@@ -22,7 +22,7 @@ int botan_pbkdf(const char* pbkdf_algo, uint8_t out[], size_t out_len,
                 const char* pass, const uint8_t salt[], size_t salt_len,
                 size_t iterations)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::PBKDF> pbkdf(Botan::get_pbkdf(pbkdf_algo));
       pbkdf->pbkdf_iterations(out, out_len, pass, salt, salt_len, iterations);
       return BOTAN_FFI_SUCCESS;
@@ -36,7 +36,7 @@ int botan_pbkdf_timed(const char* pbkdf_algo,
                       size_t ms_to_run,
                       size_t* iterations_used)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::PBKDF> pbkdf(Botan::get_pbkdf(pbkdf_algo));
       pbkdf->pbkdf_timed(out, out_len, password, salt, salt_len,
                          std::chrono::milliseconds(ms_to_run),
@@ -51,7 +51,7 @@ int botan_kdf(const char* kdf_algo,
               const uint8_t salt[], size_t salt_len,
               const uint8_t label[], size_t label_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::KDF> kdf(Botan::get_kdf(kdf_algo));
       kdf->kdf(out, out_len, secret, secret_len, salt, salt_len, label, label_len);
       return BOTAN_FFI_SUCCESS;
@@ -64,7 +64,7 @@ int botan_bcrypt_generate(uint8_t* out, size_t* out_len,
                           uint32_t flags)
    {
 #if defined(BOTAN_HAS_BCRYPT)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(out == nullptr || out_len == nullptr || pass == nullptr)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
@@ -86,7 +86,7 @@ int botan_bcrypt_generate(uint8_t* out, size_t* out_len,
 int botan_bcrypt_is_valid(const char* pass, const char* hash)
    {
 #if defined(BOTAN_HAS_BCRYPT)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       return Botan::check_bcrypt(pass, hash) ? BOTAN_FFI_SUCCESS : BOTAN_FFI_INVALID_VERIFIER;
       });
 #else
diff --git a/src/lib/ffi/ffi_keywrap.cpp b/src/lib/ffi/ffi_keywrap.cpp
index 22bb5280a..546137df0 100644
--- a/src/lib/ffi/ffi_keywrap.cpp
+++ b/src/lib/ffi/ffi_keywrap.cpp
@@ -20,7 +20,7 @@ int botan_key_wrap3394(const uint8_t key[], size_t key_len,
                        uint8_t wrapped_key[], size_t* wrapped_key_len)
    {
 #if defined(BOTAN_HAS_RFC3394_KEYWRAP)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const Botan::SymmetricKey kek_sym(kek, kek_len);
       const Botan::secure_vector<uint8_t> key_pt(key, key + key_len);
       const Botan::secure_vector<uint8_t> key_ct = Botan::rfc3394_keywrap(key_pt, kek_sym);
@@ -36,7 +36,7 @@ int botan_key_unwrap3394(const uint8_t wrapped_key[], size_t wrapped_key_len,
                          uint8_t key[], size_t* key_len)
    {
 #if defined(BOTAN_HAS_RFC3394_KEYWRAP)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const Botan::SymmetricKey kek_sym(kek, kek_len);
       const Botan::secure_vector<uint8_t> key_ct(wrapped_key, wrapped_key + wrapped_key_len);
       const Botan::secure_vector<uint8_t> key_pt = Botan::rfc3394_keyunwrap(key_ct, kek_sym);
diff --git a/src/lib/ffi/ffi_mac.cpp b/src/lib/ffi/ffi_mac.cpp
index b3237592f..22dbb2513 100644
--- a/src/lib/ffi/ffi_mac.cpp
+++ b/src/lib/ffi/ffi_mac.cpp
@@ -16,7 +16,7 @@ BOTAN_FFI_DECLARE_STRUCT(botan_mac_struct, Botan::MessageAuthenticationCode, 0xA
 
 int botan_mac_init(botan_mac_t* mac, const char* mac_name, uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(!mac || !mac_name || flags != 0)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
diff --git a/src/lib/ffi/ffi_mp.cpp b/src/lib/ffi/ffi_mp.cpp
index 87e455ccd..fc81310ea 100644
--- a/src/lib/ffi/ffi_mp.cpp
+++ b/src/lib/ffi/ffi_mp.cpp
@@ -19,7 +19,7 @@ using namespace Botan_FFI;
 
 int botan_mp_init(botan_mp_t* mp_out)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(mp_out == nullptr)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
diff --git a/src/lib/ffi/ffi_pk_op.cpp b/src/lib/ffi/ffi_pk_op.cpp
index fa3b32725..67353aa66 100644
--- a/src/lib/ffi/ffi_pk_op.cpp
+++ b/src/lib/ffi/ffi_pk_op.cpp
@@ -25,7 +25,7 @@ int botan_pk_op_encrypt_create(botan_pk_op_encrypt_t* op,
                                const char* padding,
                                uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       BOTAN_ASSERT_NONNULL(op);
 
       *op = nullptr;
@@ -62,7 +62,7 @@ int botan_pk_op_decrypt_create(botan_pk_op_decrypt_t* op,
                                const char* padding,
                                uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       BOTAN_ASSERT_NONNULL(op);
 
       *op = nullptr;
@@ -98,7 +98,7 @@ int botan_pk_op_sign_create(botan_pk_op_sign_t* op,
                             const char* hash,
                             uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       BOTAN_ASSERT_NONNULL(op);
 
       *op = nullptr;
@@ -134,7 +134,7 @@ int botan_pk_op_verify_create(botan_pk_op_verify_t* op,
                               const char* hash,
                               uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       BOTAN_ASSERT_NONNULL(op);
 
       if(flags != 0)
@@ -173,7 +173,7 @@ int botan_pk_op_key_agreement_create(botan_pk_op_ka_t* op,
                                      const char* kdf,
                                      uint32_t flags)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       BOTAN_ASSERT_NONNULL(op);
 
       *op = nullptr;
diff --git a/src/lib/ffi/ffi_pkey.cpp b/src/lib/ffi/ffi_pkey.cpp
index e377f13e7..ae7e61433 100644
--- a/src/lib/ffi/ffi_pkey.cpp
+++ b/src/lib/ffi/ffi_pkey.cpp
@@ -28,7 +28,7 @@ int botan_privkey_create(botan_privkey_t* key_obj,
                          const char* algo_params,
                          botan_rng_t rng_obj)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(key_obj == nullptr)
          return BOTAN_FFI_ERROR_NULL_POINTER;
 
@@ -60,7 +60,7 @@ int botan_privkey_load(botan_privkey_t* key, botan_rng_t rng_obj,
    {
    *key = nullptr;
 
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::DataSource_Memory src(bits, len);
 
       Botan::RandomNumberGenerator& rng = safe_get(rng_obj);
@@ -95,7 +95,7 @@ int botan_pubkey_load(botan_pubkey_t* key,
    {
    *key = nullptr;
 
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::DataSource_Memory src(bits, bits_len);
       std::unique_ptr<Botan::Public_Key> pubkey(Botan::X509::load_key(src));
 
@@ -114,7 +114,7 @@ int botan_pubkey_destroy(botan_pubkey_t key)
 
 int botan_privkey_export_pubkey(botan_pubkey_t* pubout, botan_privkey_t key_obj)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::Public_Key>
          pubkey(Botan::X509::load_key(Botan::X509::BER_encode(safe_get(key_obj))));
 
@@ -260,7 +260,7 @@ int botan_pubkey_fingerprint(botan_pubkey_t key, const char* hash_fn,
 int botan_pkcs_hash_id(const char* hash_name, uint8_t pkcs_id[], size_t* pkcs_id_len)
    {
 #if defined(BOTAN_HAS_HASH_ID)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const std::vector<uint8_t> hash_id = Botan::pkcs_hash_id(hash_name);
       return write_output(pkcs_id, pkcs_id_len, hash_id.data(), hash_id.size());
       });
diff --git a/src/lib/ffi/ffi_pkey_algs.cpp b/src/lib/ffi/ffi_pkey_algs.cpp
index 0b8c8f712..694edfeb3 100644
--- a/src/lib/ffi/ffi_pkey_algs.cpp
+++ b/src/lib/ffi/ffi_pkey_algs.cpp
@@ -270,7 +270,7 @@ int botan_privkey_load_rsa(botan_privkey_t* key,
 #if defined(BOTAN_HAS_RSA)
    *key = nullptr;
 
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       *key = new botan_privkey_struct(new Botan::RSA_PrivateKey(safe_get(rsa_p),
                                                                 safe_get(rsa_q),
                                                                 safe_get(rsa_e)));
@@ -287,7 +287,7 @@ int botan_pubkey_load_rsa(botan_pubkey_t* key,
    {
 #if defined(BOTAN_HAS_RSA)
    *key = nullptr;
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       *key = new botan_pubkey_struct(new Botan::RSA_PublicKey(safe_get(n), safe_get(e)));
       return BOTAN_FFI_SUCCESS;
       });
@@ -340,7 +340,7 @@ int botan_privkey_load_dsa(botan_privkey_t* key,
 #if defined(BOTAN_HAS_DSA)
    *key = nullptr;
 
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::Null_RNG null_rng;
       Botan::DL_Group group(safe_get(p), safe_get(q), safe_get(g));
       *key = new botan_privkey_struct(new Botan::DSA_PrivateKey(null_rng, group, safe_get(x)));
@@ -358,7 +358,7 @@ int botan_pubkey_load_dsa(botan_pubkey_t* key,
 #if defined(BOTAN_HAS_DSA)
    *key = nullptr;
 
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::DL_Group group(safe_get(p), safe_get(q), safe_get(g));
       *key = new botan_pubkey_struct(new Botan::DSA_PublicKey(group, safe_get(y)));
       return BOTAN_FFI_SUCCESS;
@@ -407,7 +407,7 @@ int botan_pubkey_load_ecdsa(botan_pubkey_t* key,
                             const char* curve_name)
    {
 #if defined(BOTAN_HAS_ECDSA)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::ECDSA_PublicKey> p_key;
 
       int rc = pubkey_load_ec(p_key, safe_get(public_x), safe_get(public_y), curve_name);
@@ -427,7 +427,7 @@ int botan_privkey_load_ecdsa(botan_privkey_t* key,
                              const char* curve_name)
    {
 #if defined(BOTAN_HAS_ECDSA)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::ECDSA_PrivateKey> p_key;
       int rc = privkey_load_ec(p_key, safe_get(scalar), curve_name);
       if(rc == BOTAN_FFI_SUCCESS)
@@ -447,7 +447,7 @@ int botan_pubkey_load_elgamal(botan_pubkey_t* key,
    {
 #if defined(BOTAN_HAS_ELGAMAL)
    *key = nullptr;
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::DL_Group group(safe_get(p), safe_get(g));
       *key = new botan_pubkey_struct(new Botan::ElGamal_PublicKey(group, safe_get(y)));
       return BOTAN_FFI_SUCCESS;
@@ -463,7 +463,7 @@ int botan_privkey_load_elgamal(botan_privkey_t* key,
    {
 #if defined(BOTAN_HAS_ELGAMAL)
    *key = nullptr;
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::Null_RNG null_rng;
       Botan::DL_Group group(safe_get(p), safe_get(g));
       *key = new botan_privkey_struct(new Botan::ElGamal_PrivateKey(null_rng, group, safe_get(x)));
@@ -487,7 +487,7 @@ int botan_privkey_load_dh(botan_privkey_t* key,
    {
 #if defined(BOTAN_HAS_DIFFIE_HELLMAN)
    *key = nullptr;
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::Null_RNG null_rng;
       Botan::DL_Group group(safe_get(p), safe_get(g));
       *key = new botan_privkey_struct(new Botan::DH_PrivateKey(null_rng, group, safe_get(x)));
@@ -504,7 +504,7 @@ int botan_pubkey_load_dh(botan_pubkey_t* key,
    {
 #if defined(BOTAN_HAS_DIFFIE_HELLMAN)
    *key = nullptr;
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::DL_Group group(safe_get(p), safe_get(g));
       *key = new botan_pubkey_struct(new Botan::DH_PublicKey(group, safe_get(y)));
       return BOTAN_FFI_SUCCESS;
@@ -536,7 +536,7 @@ int botan_pubkey_load_ecdh(botan_pubkey_t* key,
                            const char* curve_name)
    {
 #if defined(BOTAN_HAS_ECDH)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::ECDH_PublicKey> p_key;
       int rc = pubkey_load_ec(p_key, safe_get(public_x), safe_get(public_y), curve_name);
 
@@ -555,7 +555,7 @@ int botan_privkey_load_ecdh(botan_privkey_t* key,
                             const char* curve_name)
    {
 #if defined(BOTAN_HAS_ECDH)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::ECDH_PrivateKey> p_key;
       int rc = privkey_load_ec(p_key, safe_get(scalar), curve_name);
       if(rc == BOTAN_FFI_SUCCESS)
@@ -582,7 +582,7 @@ int botan_pubkey_sm2_compute_za(uint8_t out[],
       return BOTAN_FFI_ERROR_NULL_POINTER;
 
 #if defined(BOTAN_HAS_SM2)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const Botan::Public_Key& pub_key = safe_get(key);
       const Botan::EC_PublicKey* ec_key = dynamic_cast<const Botan::EC_PublicKey*>(&pub_key);
 
@@ -612,7 +612,7 @@ int botan_pubkey_load_sm2(botan_pubkey_t* key,
                           const char* curve_name)
    {
 #if defined(BOTAN_HAS_SM2)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::SM2_Signature_PublicKey> p_key;
       if(!pubkey_load_ec(p_key, safe_get(public_x), safe_get(public_y), curve_name))
          {
@@ -632,7 +632,7 @@ int botan_privkey_load_sm2(botan_privkey_t* key,
                            const char* curve_name)
    {
 #if defined(BOTAN_HAS_SM2)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::SM2_Signature_PrivateKey> p_key;
       int rc = privkey_load_ec(p_key, safe_get(scalar), curve_name);
 
@@ -652,7 +652,7 @@ int botan_pubkey_load_sm2_enc(botan_pubkey_t* key,
                               const char* curve_name)
    {
 #if defined(BOTAN_HAS_SM2)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::SM2_Encryption_PublicKey> p_key;
       if(!pubkey_load_ec(p_key, safe_get(public_x), safe_get(public_y), curve_name))
          {
@@ -672,7 +672,7 @@ int botan_privkey_load_sm2_enc(botan_privkey_t* key,
                                const char* curve_name)
    {
 #if defined(BOTAN_HAS_SM2)
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       std::unique_ptr<Botan::SM2_Encryption_PrivateKey> p_key;
       int rc = privkey_load_ec(p_key, safe_get(scalar), curve_name);
 
@@ -693,7 +693,7 @@ int botan_privkey_load_ed25519(botan_privkey_t* key,
    {
 #if defined(BOTAN_HAS_ED25519)
    *key = nullptr;
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const Botan::secure_vector<uint8_t> privkey_vec(privkey, privkey + 32);
       *key = new botan_privkey_struct(new Botan::Ed25519_PrivateKey(privkey_vec));
       return BOTAN_FFI_SUCCESS;
@@ -709,7 +709,7 @@ int botan_pubkey_load_ed25519(botan_pubkey_t* key,
    {
 #if defined(BOTAN_HAS_ED25519)
    *key = nullptr;
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       const std::vector<uint8_t> pubkey_vec(pubkey, pubkey + 32);
       *key = new botan_pubkey_struct(new Botan::Ed25519_PublicKey(pubkey_vec));
       return BOTAN_FFI_SUCCESS;
@@ -780,7 +780,7 @@ int botan_mceies_decrypt(botan_privkey_t mce_key_obj,
                          const uint8_t ad[], size_t ad_len,
                          uint8_t out[], size_t* out_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::Private_Key& key = safe_get(mce_key_obj);
 
 #if defined(BOTAN_HAS_MCELIECE) && defined(BOTAN_HAS_MCEIES)
@@ -803,7 +803,7 @@ int botan_mceies_encrypt(botan_pubkey_t mce_key_obj,
                          const uint8_t ad[], size_t ad_len,
                          uint8_t out[], size_t* out_len)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       Botan::Public_Key& key = safe_get(mce_key_obj);
       Botan::RandomNumberGenerator& rng = safe_get(rng_obj);
 
diff --git a/src/lib/ffi/ffi_rng.cpp b/src/lib/ffi/ffi_rng.cpp
index 88c522dfd..6c27b2e7e 100644
--- a/src/lib/ffi/ffi_rng.cpp
+++ b/src/lib/ffi/ffi_rng.cpp
@@ -16,7 +16,7 @@ using namespace Botan_FFI;
 
 int botan_rng_init(botan_rng_t* rng_out, const char* rng_type)
    {
-   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() {
+   return ffi_guard_thunk(BOTAN_CURRENT_FUNCTION, [=]() -> int {
       if(rng_out == nullptr)
          return BOTAN_FFI_ERROR_NULL_POINTER;