Merge bitcoin-core/secp256k1#1231: Move SECP256K1_INLINE macro definition out from include/secp256k1.h

8e142ca4102ade1b90dcb06d6c78405ef3220599 Move `SECP256K1_INLINE` macro definition out from `include/secp256k1.h` (Hennadii Stepanov)
77445898a5852ecd38ab95cfb329333a82673115 Remove `SECP256K1_INLINE` usage from examples (Hennadii Stepanov)

Pull request description:

  From [IRC](https://gnusha.org/secp256k1/2023-01-31.log):
  > 06:29 \< hebasto\> What are reasons to define the `SECP256K1_INLINE` macro in user's `include/secp256k1.h` header, while it is used internally only?
  > 06:32 \< hebasto\> I mean, any other (or a new dedicated) header in `src` looks more appropriate, no?
  > 06:35 \< sipa\> I think it may just predate any "utility" internal headers.
  > 06:42 \< sipa\> I think it makes sense to move it to util.h

  Pros:
  - it is a step in direction to better organized headers (in context of #924, #1039)

  Cons:
  - code duplication for `SECP256K1_GNUC_PREREQ` macro

ACKs for top commit:
  sipa:
    utACK 8e142ca4102ade1b90dcb06d6c78405ef3220599
  real-or-random:
    utACK 8e142ca410

Tree-SHA512: 180e0ba7c2ef242b765f20698b67d06c492b7b70866c21db27c18d8b2e85c3e11f86c6cb99ffa88bbd23891ce3ee8a24bc528f2c91167ec2fddc167463f78eac

examples/examples_util.h

@@ -77,7 +77,7 @@ static void print_hex(unsigned char* data, size_t size) {
 #include <Windows.h>
 #endif
 /* Cleanses memory to prevent leaking sensitive info. Won't be optimized out. */
-static SECP256K1_INLINE void secure_erase(void *ptr, size_t len) {
+static void secure_erase(void *ptr, size_t len) {
 #if defined(_MSC_VER)
     /* SecureZeroMemory is guaranteed not to be optimized out by MSVC. */
     SecureZeroMemory(ptr, len);

include/secp256k1.h

@@ -122,18 +122,6 @@ typedef int (*secp256k1_nonce_function)(
 #  endif
 # endif
 
-# if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
-#  if SECP256K1_GNUC_PREREQ(2,7)
-#   define SECP256K1_INLINE __inline__
-#  elif (defined(_MSC_VER))
-#   define SECP256K1_INLINE __inline
-#  else
-#   define SECP256K1_INLINE
-#  endif
-# else
-#  define SECP256K1_INLINE inline
-# endif
-
 /*  When this header is used at build-time the SECP256K1_BUILD define needs to be set
  *  to correctly setup export attributes and nullness checks.  This is normally done
  *  by secp256k1.c but to guard against this header being included before secp256k1.c

src/field_5x52_asm_impl.h

@@ -14,6 +14,8 @@
 #ifndef SECP256K1_FIELD_INNER5X52_IMPL_H
 #define SECP256K1_FIELD_INNER5X52_IMPL_H
 
+#include "util.h"
+
 SECP256K1_INLINE static void secp256k1_fe_mul_inner(uint64_t *r, const uint64_t *a, const uint64_t * SECP256K1_RESTRICT b) {
 /**
  * Registers: rdx:rax = multiplication accumulator

src/field_5x52_int128_impl.h

@@ -10,6 +10,7 @@
 #include <stdint.h>
 
 #include "int128.h"
+#include "util.h"
 
 #ifdef VERIFY
 #define VERIFY_BITS(x, n) VERIFY_CHECK(((x) >> (n)) == 0)

src/group_impl.h

@@ -9,6 +9,7 @@
 
 #include "field.h"
 #include "group.h"
+#include "util.h"
 
 /* Begin of section generated by sage/gen_exhaustive_groups.sage. */
 #define SECP256K1_G_ORDER_7 SECP256K1_GE_CONST(\

src/int128_native_impl.h

@@ -2,6 +2,7 @@
 #define SECP256K1_INT128_NATIVE_IMPL_H
 
 #include "int128.h"
+#include "util.h"
 
 static SECP256K1_INLINE void secp256k1_u128_load(secp256k1_uint128 *r, uint64_t hi, uint64_t lo) {
     *r = (((uint128_t)hi) << 64) + lo;

src/int128_struct_impl.h

@@ -2,6 +2,7 @@
 #define SECP256K1_INT128_STRUCT_IMPL_H
 
 #include "int128.h"
+#include "util.h"
 
 #if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64)) /* MSVC */
 #    include <intrin.h>

src/modules/extrakeys/main_impl.h

@@ -9,6 +9,7 @@
 
 #include "../../../include/secp256k1.h"
 #include "../../../include/secp256k1_extrakeys.h"
+#include "../../util.h"
 
 static SECP256K1_INLINE int secp256k1_xonly_pubkey_load(const secp256k1_context* ctx, secp256k1_ge *ge, const secp256k1_xonly_pubkey *pubkey) {
     return secp256k1_pubkey_load(ctx, ge, (const secp256k1_pubkey *) pubkey);

src/scalar_4x64_impl.h

@@ -10,6 +10,7 @@
 #include "checkmem.h"
 #include "int128.h"
 #include "modinv64_impl.h"
+#include "util.h"
 
 /* Limbs of the secp256k1 order. */
 #define SECP256K1_N_0 ((uint64_t)0xBFD25E8CD0364141ULL)

src/scalar_8x32_impl.h

@@ -9,6 +9,7 @@
 
 #include "checkmem.h"
 #include "modinv32_impl.h"
+#include "util.h"
 
 /* Limbs of the secp256k1 order. */
 #define SECP256K1_N_0 ((uint32_t)0xD0364141UL)

src/scalar_low_impl.h

@@ -9,6 +9,7 @@
 
 #include "checkmem.h"
 #include "scalar.h"
+#include "util.h"
 
 #include <string.h>
 

src/testrand.h

@@ -7,6 +7,8 @@
 #ifndef SECP256K1_TESTRAND_H
 #define SECP256K1_TESTRAND_H
 
+#include "util.h"
+
 /* A non-cryptographic RNG used only for test infrastructure. */
 
 /** Seed the pseudorandom number generator for testing. */

src/testrand_impl.h

@@ -13,6 +13,7 @@
 
 #include "testrand.h"
 #include "hash.h"
+#include "util.h"
 
 static uint64_t secp256k1_test_state[4];
 static uint64_t secp256k1_test_rng_integer;

src/tests_exhaustive.c

@@ -20,6 +20,7 @@
 #include "testrand_impl.h"
 #include "ecmult_compute_table_impl.h"
 #include "ecmult_gen_compute_table_impl.h"
+#include "util.h"
 
 static int count = 2;
 

src/util.h

@@ -7,6 +7,8 @@
 #ifndef SECP256K1_UTIL_H
 #define SECP256K1_UTIL_H
 
+#include "../include/secp256k1.h"
+
 #include <stdlib.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -17,6 +19,18 @@
 #define DEBUG_CONFIG_MSG(x) "DEBUG_CONFIG: " x
 #define DEBUG_CONFIG_DEF(x) DEBUG_CONFIG_MSG(#x "=" STR(x))
 
+# if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
+#  if SECP256K1_GNUC_PREREQ(2,7)
+#   define SECP256K1_INLINE __inline__
+#  elif (defined(_MSC_VER))
+#   define SECP256K1_INLINE __inline
+#  else
+#   define SECP256K1_INLINE
+#  endif
+# else
+#  define SECP256K1_INLINE inline
+# endif
+
 typedef struct {
     void (*fn)(const char *text, void* data);
     const void* data;