windows fix

Author: jaoleal

libbitcoinkernel-sys/build.rs

@@ -11,8 +11,30 @@ fn main() {
 
     let build_config = "RelWithDebInfo";
 
+    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
+
+    // Prevent the cmake crate from injecting cc-derived compiler flags
+    // (e.g. /MD on MSVC) that conflict with Bitcoin Core's own CMakeLists.txt
+    // flag management. Bitcoin Core's build system manages all necessary
+    // compiler flags itself via target_compile_options.
+    //
+    // On Windows/MSVC, CMake normally adds /DWIN32 and /D_WINDOWS via
+    // CMAKE_CXX_FLAGS_INIT, but setting CMAKE_CXX_FLAGS to empty overrides
+    // that. We must restore these definitions so that code guarded by
+    // #if defined(WIN32) (e.g. cleanse.cpp's SecureZeroMemory path) compiles
+    // correctly instead of falling through to GCC-style inline assembly.
+    let (c_flags, cxx_flags) = if target_os == "windows" {
+        ("/DWIN32 /D_WINDOWS", "/DWIN32 /D_WINDOWS")
+    } else {
+        ("", "")
+    };
+
     let output_dir = cmake::Config::new("bitcoin")
         .profile(build_config)
+        .no_default_flags(true)
+        .define("CMAKE_C_FLAGS", c_flags)
+        .define("CMAKE_CXX_FLAGS", cxx_flags)
+        .define("CMAKE_ASM_FLAGS", "")
         .define("BUILD_KERNEL_LIB", "ON")
         .define("BUILD_TESTS", "OFF")
         .define("BUILD_BENCH", "OFF")
@@ -64,7 +86,6 @@ fn main() {
         .expect("Couldn't write bindings!");
 
     let compiler = cc::Build::new().get_compiler();
-    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
 
     if target_os == "windows" {
         println!("cargo:rustc-link-lib=bcrypt");