build: Fix build on macOS 15 and Nix environment (#7953)

BUILD.md

@@ -42,6 +42,8 @@ Our Linux CI tooling is distro-independent and uses a Nix-based environment, so
 ### macOS
 
 Many `xrpld` engineers use macOS for development.
+The minimum supported version is macOS 15 (Sequoia).
+CI testing is done in macOS 26 (Tahoe), but the build defaults `CMAKE_OSX_DEPLOYMENT_TARGET` to 15.
 
 ### Windows
 

CMakeLists.txt

@@ -13,6 +13,23 @@ if(DEFINED CMAKE_MODULE_PATH)
 endif()
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 
+# Must be set before project() because project() consumes it when configuring the compiler and SDK.
+# A user-provided -DCMAKE_OSX_DEPLOYMENT_TARGET still takes precedence.
+#
+# CMAKE_SYSTEM_NAME can't be used before project(), so CMAKE_HOST_SYSTEM_NAME is used instead.
+#
+# When CMAKE_OSX_DEPLOYMENT_TARGET is bumped to >=26.0, FastFloat dependency won't be needed anymore
+if(
+    CMAKE_HOST_SYSTEM_NAME STREQUAL "Darwin"
+    AND NOT DEFINED CMAKE_OSX_DEPLOYMENT_TARGET
+)
+    set(CMAKE_OSX_DEPLOYMENT_TARGET
+        "15.0"
+        CACHE STRING
+        "Minimum macOS deployment version"
+    )
+endif()
+
 project(xrpl)
 set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_CXX_STANDARD 23)
@@ -87,6 +104,7 @@ include(deps/Boost)
 add_subdirectory(external/antithesis-sdk)
 find_package(date REQUIRED)
 find_package(ed25519 REQUIRED)
+find_package(FastFloat REQUIRED)
 find_package(gRPC REQUIRED)
 find_package(LibArchive REQUIRED)
 find_package(lz4 REQUIRED)
@@ -102,6 +120,7 @@ target_link_libraries(
     xrpl_libs
     INTERFACE
         ed25519::ed25519
+        FastFloat::fast_float
         lz4::lz4
         mpt-crypto::mpt-crypto
         OpenSSL::Crypto

conan.lock

@@ -20,6 +20,7 @@
         "jemalloc/5.3.1#1fc58d55316041f10fbc1e8a2eae632a%1776700028.228",
         "gtest/1.17.0#5224b3b3ff3b4ce1133cbdd27d53ee7d%1782392402.791979",
         "grpc/1.81.1#f729f6d75992d20f9c72828e9142d62f%1783945160.094135",
+        "fast_float/8.2.10#f6f28d6bb22112078e7dbda611caf681%1782494504.298",
         "ed25519/2015.03#ae761bdc52730a843f0809bdf6c1b1f6%1782307148.15562",
         "date/3.0.4#862e11e80030356b53c2c38599ceb32b%1782392402.538492",
         "c-ares/1.34.6#545240bb1c40e2cacd4362d6b8967650%1782392402.681654",
@@ -34,7 +35,7 @@
         "protobuf/6.33.5#ff253ead763bd8d9904a52979cd21e81%1782392410.233933",
         "nasm/2.16.01#31e26f2ee3c4346ecd347911bd126904%1782395690.33162",
         "msys2/cci.latest#d22fe7b2808f5fd34d0a7923ace9c54f%1770657326.649",
-        "m4/1.4.19#34c4bbc3eeebe98ca6edf2f52d602e7d%1777282960.259",
+        "m4/1.4.19#1727f439cf74e83826ec96d0b4904eee%1784541921.659",
         "cmake/4.3.3#840cf00ea09777e05c2050a50a82c722%1782392418.696091",
         "b2/5.4.2#ffd6084a119587e70f11cd45d1a386e2%1782392402.624226",
         "automake/1.16.5#b91b7c384c3deaa9d535be02da14d04f%1755524470.56",

conan/profiles/default

@@ -5,6 +5,13 @@
 {% if os == "Linux" %}
 {% set compiler_version = detect_api.default_compiler_version(compiler, version) %}
 {% endif %}
+{% if os == "Macos" %}
+{# Minimum macOS the dependencies target. #}
+{# Without this, Conan builds each dependency against the (possibly newer) host SDK, so the #}
+{# dependency objects target a newer macOS than the binary and the linker warns. #}
+{# Keep at or below CMAKE_OSX_DEPLOYMENT_TARGET in CMakeLists.txt. #}
+{% set min_macos_version = "15.0" %}
+{% endif %}
 
 [settings]
 os={{ os }}
@@ -18,6 +25,9 @@ compiler.runtime=static
 {% else %}
 compiler.libcxx={{ detect_api.detect_libcxx(compiler, version, compiler_exe) }}
 {% endif %}
+{% if os == "Macos" %}
+os.version={{ min_macos_version }}
+{% endif %}
 
 [conf]
 {# The Boost recipe builds with b2, which doesn't use Conan's toolchain files. #}
@@ -41,3 +51,13 @@ tools.build:compiler_executables={'c':'{{ cc_exe }}','cpp':'{{ cxx_exe }}'}
 {# More info: https://docs.conan.io/2/reference/extensions/binary_compatibility.html #}
 user.package:cppstd_version=23
 tools.info.package_id:confs+=["user.package:cppstd_version"]
+
+{% if os == "Macos" %}
+[buildenv]
+{# os.version adds -mmacosx-version-min to compiler command lines, #}
+{# but Boost.Context's b2 assembly (.S) rule ignores it, #}
+{# so those objects keep the host SDK version and still warn at link time. #}
+{# clang's assembler honors this env var regardless, pinning them. #}
+{# Scoped to boost/* since it is the only gap. #}
+boost/*:MACOSX_DEPLOYMENT_TARGET={{ min_macos_version }}
+{% endif %}

conanfile.py

@@ -29,6 +29,7 @@ class Xrpl(ConanFile):
 
     requires = [
         "ed25519/2015.03",
+        "fast_float/8.2.10",
         "grpc/1.81.1",
         "libarchive/3.8.7",
         "nudb/2.0.9",
@@ -211,6 +212,7 @@ class Xrpl(ConanFile):
             "boost::thread",
             "date::date",
             "ed25519::ed25519",
+            "fast_float::fast_float",
             "grpc::grpc++",
             "libarchive::libarchive",
             "lz4::lz4",

sanitizers/suppressions/ubsan.supp

@@ -102,6 +102,10 @@ undefined:nudb
 # Snappy compression library intentional overflows
 unsigned-integer-overflow:snappy.cc
 
+# fast_float parses floats with a SWAR trick (parse_eight_digits_unrolled) that
+# multiplies eight packed digits modulo 2^64; the wraparound is by design.
+unsigned-integer-overflow:fast_float
+
 # Abseil intentional overflows in hashing, RNG and time arithmetic.
 # Matched at library scope (like boost above): the wraparound is by design
 # across many absl files (hash mixing, raw_hash_set probing, duration math,

src/libxrpl/json/json_reader.cpp

@@ -3,9 +3,11 @@
 #include <xrpl/basics/contract.h>
 #include <xrpl/json/json_value.h>
 
+#include <fast_float/fast_float.h>  // IWYU pragma: keep
+#include <fast_float/parse_number.h>
+
 #include <algorithm>
 #include <cctype>
-#include <charconv>
 #include <cstdint>
 #include <cstdio>
 #include <istream>
@@ -605,8 +607,14 @@ Reader::decodeNumber(Token& token)
 bool
 Reader::decodeDouble(Token& token)
 {
+    // Sanity check to avoid buffer overflow exploits.
+    if (token.end < token.start)
+    {
+        return addError("Unable to parse token length", token);
+    }
+
     double value = 0;
-    auto const [ptr, ec] = std::from_chars(token.start, token.end, value);
+    auto const [ptr, ec] = fast_float::from_chars(token.start, token.end, value);
 
     // Reject anything from_chars could not turn into a finite double:
     //   - ec != std::errc{}: no valid conversion, or an out-of-range magnitude