Merge bitcoin/bitcoin#26159: build: Remove `stdlib.h` from header checks

553ff452c0e95a9647d35f10f67e45f24bd2d9b7 build: remove stdlib.h from header checks (fanquake)
a63d4cb26a2830b297288aa6acf5b69108353334 refactor: use <cstdlib> over stdlib.h (fanquake)

Pull request description:

  We already use a mix of `<cstlib>` and `stdlib.h` unconditionally throughout
  the codebase.

  Us checking this header also duplicates work already done by autotools.
  Currently stdlib.h is checked for 3 times during a ./configure run, after
  this change, at least it's only twice.

  Similar to #26150.

ACKs for top commit:
  kristapsk:
    ACK 553ff452c0e95a9647d35f10f67e45f24bd2d9b7
  TheCharlatan:
    ACK 553ff452c0e95a9647d35f10f67e45f24bd2d9b7

Tree-SHA512: 0a43d39d3df180a1614dbd3a1ee1531b0969ffe4a0c09dfe9d2f3f0ec16196b5fd7523309f6722936a8c8b20908508724e1903e939dd81c3b4538d85d0f42953

23 files changed, 24 insertions, 25 deletions

diff --git a/configure.ac b/configure.ac
index 5b1ce4ed7e..82cb469864 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1010,7 +1010,7 @@ if test "$TARGET_OS" = "darwin"; then
   AX_CHECK_LINK_FLAG([-Wl,-bind_at_load], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-bind_at_load"], [], [$LDFLAG_WERROR])
 fi
 
-AC_CHECK_HEADERS([endian.h sys/endian.h byteswap.h stdlib.h unistd.h sys/types.h sys/stat.h sys/select.h sys/prctl.h sys/sysctl.h vm/vm_param.h sys/vmmeter.h sys/resources.h])
+AC_CHECK_HEADERS([endian.h sys/endian.h byteswap.h unistd.h sys/types.h sys/stat.h sys/select.h sys/prctl.h sys/sysctl.h vm/vm_param.h sys/vmmeter.h sys/resources.h])
 
 AC_CHECK_DECLS([getifaddrs, freeifaddrs],[CHECK_SOCKET],,
     [#include <sys/types.h>
diff --git a/src/consensus/consensus.h b/src/consensus/consensus.h
index b2a31e3ba4..10bdbf31a8 100644
--- a/src/consensus/consensus.h
+++ b/src/consensus/consensus.h
@@ -6,7 +6,7 @@
 #ifndef BITCOIN_CONSENSUS_CONSENSUS_H
 #define BITCOIN_CONSENSUS_CONSENSUS_H
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <stdint.h>
 
 /** The maximum allowed size for a serialized block, in bytes (only for buffer size limits) */
diff --git a/src/crypto/chacha20.h b/src/crypto/chacha20.h
index 69fbbe9fa5..de16a77878 100644
--- a/src/crypto/chacha20.h
+++ b/src/crypto/chacha20.h
@@ -5,8 +5,8 @@
 #ifndef BITCOIN_CRYPTO_CHACHA20_H
 #define BITCOIN_CRYPTO_CHACHA20_H
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 /** A class for ChaCha20 256-bit stream cipher developed by Daniel J. Bernstein
     https://cr.yp.to/chacha/chacha-20080128.pdf */
diff --git a/src/crypto/hkdf_sha256_32.h b/src/crypto/hkdf_sha256_32.h
index fa1e42aec1..878b03a37f 100644
--- a/src/crypto/hkdf_sha256_32.h
+++ b/src/crypto/hkdf_sha256_32.h
@@ -7,8 +7,8 @@
 
 #include <crypto/hmac_sha256.h>
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 /** A rfc5869 HKDF implementation with HMAC_SHA256 and fixed key output length of 32 bytes (L=32) */
 class CHKDF_HMAC_SHA256_L32
diff --git a/src/crypto/hmac_sha256.h b/src/crypto/hmac_sha256.h
index d31fda1dd1..9c25edd7c1 100644
--- a/src/crypto/hmac_sha256.h
+++ b/src/crypto/hmac_sha256.h
@@ -7,8 +7,8 @@
 
 #include <crypto/sha256.h>
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 /** A hasher class for HMAC-SHA-256. */
 class CHMAC_SHA256
diff --git a/src/crypto/hmac_sha512.h b/src/crypto/hmac_sha512.h
index 1ea9a3671e..6acce8992e 100644
--- a/src/crypto/hmac_sha512.h
+++ b/src/crypto/hmac_sha512.h
@@ -7,8 +7,8 @@
 
 #include <crypto/sha512.h>
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 /** A hasher class for HMAC-SHA-512. */
 class CHMAC_SHA512
diff --git a/src/crypto/poly1305.h b/src/crypto/poly1305.h
index 1598b013b9..c80faada7e 100644
--- a/src/crypto/poly1305.h
+++ b/src/crypto/poly1305.h
@@ -5,8 +5,8 @@
 #ifndef BITCOIN_CRYPTO_POLY1305_H
 #define BITCOIN_CRYPTO_POLY1305_H
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 #define POLY1305_KEYLEN 32
 #define POLY1305_TAGLEN 16
diff --git a/src/crypto/ripemd160.h b/src/crypto/ripemd160.h
index 38ea375c1f..f1d89b8407 100644
--- a/src/crypto/ripemd160.h
+++ b/src/crypto/ripemd160.h
@@ -5,8 +5,8 @@
 #ifndef BITCOIN_CRYPTO_RIPEMD160_H
 #define BITCOIN_CRYPTO_RIPEMD160_H
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 /** A hasher class for RIPEMD-160. */
 class CRIPEMD160
diff --git a/src/crypto/sha1.h b/src/crypto/sha1.h
index 8b4568ee12..6ef0187efd 100644
--- a/src/crypto/sha1.h
+++ b/src/crypto/sha1.h
@@ -5,8 +5,8 @@
 #ifndef BITCOIN_CRYPTO_SHA1_H
 #define BITCOIN_CRYPTO_SHA1_H
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 /** A hasher class for SHA1. */
 class CSHA1
diff --git a/src/crypto/sha256.h b/src/crypto/sha256.h
index 028ee14345..24bd1f2e7e 100644
--- a/src/crypto/sha256.h
+++ b/src/crypto/sha256.h
@@ -5,8 +5,8 @@
 #ifndef BITCOIN_CRYPTO_SHA256_H
 #define BITCOIN_CRYPTO_SHA256_H
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 #include <string>
 
 /** A hasher class for SHA-256. */
diff --git a/src/crypto/sha256_sse4.cpp b/src/crypto/sha256_sse4.cpp
index f1a7fefea3..bc69703607 100644
--- a/src/crypto/sha256_sse4.cpp
+++ b/src/crypto/sha256_sse4.cpp
@@ -5,8 +5,8 @@
 // This is a translation to GCC extended asm syntax from YASM code by Intel
 // (available at the bottom of this file).
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 #if defined(__x86_64__) || defined(__amd64__)
 
diff --git a/src/crypto/sha3.h b/src/crypto/sha3.h
index 88d8c1204d..78608eae76 100644
--- a/src/crypto/sha3.h
+++ b/src/crypto/sha3.h
@@ -7,8 +7,8 @@
 
 #include <span.h>
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 //! The Keccak-f[1600] transform.
 void KeccakF(uint64_t (&st)[25]);
diff --git a/src/crypto/sha512.h b/src/crypto/sha512.h
index 21ca930c75..7356dff6d9 100644
--- a/src/crypto/sha512.h
+++ b/src/crypto/sha512.h
@@ -5,8 +5,8 @@
 #ifndef BITCOIN_CRYPTO_SHA512_H
 #define BITCOIN_CRYPTO_SHA512_H
 
+#include <cstdlib>
 #include <stdint.h>
-#include <stdlib.h>
 
 /** A hasher class for SHA-512. */
 class CSHA512
diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index 19caefe400..41e048a877 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -22,10 +22,10 @@
 #include <util/translation.h>
 
 #include <cstdio>
+#include <cstdlib>
 #include <deque>
 #include <memory>
 #include <optional>
-#include <stdlib.h>
 #include <string>
 
 #include <sys/types.h>
diff --git a/src/ipc/interfaces.cpp b/src/ipc/interfaces.cpp
index f4115db982..ee0d4123ce 100644
--- a/src/ipc/interfaces.cpp
+++ b/src/ipc/interfaces.cpp
@@ -13,10 +13,10 @@
 #include <util/system.h>
 
 #include <cstdio>
+#include <cstdlib>
 #include <functional>
 #include <memory>
 #include <stdexcept>
-#include <stdlib.h>
 #include <string.h>
 #include <string>
 #include <unistd.h>
diff --git a/src/ipc/process.cpp b/src/ipc/process.cpp
index 9036b80c45..9474ad2c4a 100644
--- a/src/ipc/process.cpp
+++ b/src/ipc/process.cpp
@@ -10,10 +10,10 @@
 #include <util/strencodings.h>
 
 #include <cstdint>
+#include <cstdlib>
 #include <exception>
 #include <iostream>
 #include <stdexcept>
-#include <stdlib.h>
 #include <string.h>
 #include <system_error>
 #include <unistd.h>
diff --git a/src/memusage.h b/src/memusage.h
index a6e894129a..fd85a7956c 100644
--- a/src/memusage.h
+++ b/src/memusage.h
@@ -8,9 +8,8 @@
 #include <indirectmap.h>
 #include <prevector.h>
 
-#include <stdlib.h>
-
 #include <cassert>
+#include <cstdlib>
 #include <map>
 #include <memory>
 #include <set>
diff --git a/src/prevector.h b/src/prevector.h
index a52510930a..7df5a067a2 100644
--- a/src/prevector.h
+++ b/src/prevector.h
@@ -6,7 +6,7 @@
 #define BITCOIN_PREVECTOR_H
 
 #include <assert.h>
-#include <stdlib.h>
+#include <cstdlib>
 #include <stdint.h>
 #include <string.h>
 
diff --git a/src/random.cpp b/src/random.cpp
index f92e679a00..eab54630b1 100644
--- a/src/random.cpp
+++ b/src/random.cpp
@@ -21,7 +21,7 @@
 #include <util/time.h> // for GetTimeMicros()
 
 #include <cmath>
-#include <stdlib.h>
+#include <cstdlib>
 #include <thread>
 
 #ifndef WIN32
diff --git a/src/script/miniscript.h b/src/script/miniscript.h
index c4f41e0adf..6faf2624fd 100644
--- a/src/script/miniscript.h
+++ b/src/script/miniscript.h
@@ -13,8 +13,8 @@
 #include <string>
 #include <vector>
 
-#include <stdlib.h>
 #include <assert.h>
+#include <cstdlib>
 
 #include <policy/policy.h>
 #include <primitives/transaction.h>
diff --git a/src/support/cleanse.h b/src/support/cleanse.h
index 8c1210a114..b1227770c7 100644
--- a/src/support/cleanse.h
+++ b/src/support/cleanse.h
@@ -6,7 +6,7 @@
 #ifndef BITCOIN_SUPPORT_CLEANSE_H
 #define BITCOIN_SUPPORT_CLEANSE_H
 
-#include <stdlib.h>
+#include <cstdlib>
 
 /** Secure overwrite a buffer (possibly containing secret data) with zero-bytes. The write
  * operation will not be optimized out by the compiler. */
diff --git a/src/test/blockchain_tests.cpp b/src/test/blockchain_tests.cpp
index c8e8cdeeb3..0157e25071 100644
--- a/src/test/blockchain_tests.cpp
+++ b/src/test/blockchain_tests.cpp
@@ -4,13 +4,13 @@
 
 #include <boost/test/unit_test.hpp>
 
-#include <stdlib.h>
-
 #include <chain.h>
 #include <rpc/blockchain.h>
 #include <test/util/setup_common.h>
 #include <util/string.h>
 
+#include <cstdlib>
+
 /* Equality between doubles is imprecise. Comparison should be done
  * with a small threshold of tolerance, rather than exact equality.
  */
diff --git a/src/test/raii_event_tests.cpp b/src/test/raii_event_tests.cpp
index c489ac04e9..d4487cd941 100644
--- a/src/test/raii_event_tests.cpp
+++ b/src/test/raii_event_tests.cpp
@@ -4,8 +4,8 @@
 
 #include <event2/event.h>
 
+#include <cstdlib>
 #include <map>
-#include <stdlib.h>
 
 #include <support/events.h>