Add support for building with clang-cl

.github/workflows/ci.yml

@@ -33,15 +33,27 @@ jobs:
           - target: shared
             arch: x86_64
             host_os: windows-2022
+            compiler: msvc
           - target: static
             arch: x86_64
             host_os: windows-2022
+            compiler: msvc
           - target: amalgamation
             arch: x86_64
             host_os: windows-2022
+            compiler: msvc
+          - target: shared
+            arch: x86
+            host_os: windows-2022
+            compiler: msvc
           - target: shared
+            arch: x86_64
+            host_os: windows-2022
+            compiler: clangcl
+          - target: static
             arch: x86
             host_os: windows-2022
+            compiler: clangcl
 
     runs-on: ${{ matrix.host_os }}
 
@@ -52,11 +64,11 @@ jobs:
         uses: ./.github/actions/setup-build-agent
         with:
           target: ${{ matrix.target }}
-          cache-key: ${{ matrix.host_os }}-msvc-${{ matrix.arch }}-${{ matrix.target }}
+          cache-key: ${{ matrix.host_os }}-${{ matrix.compiler }}-${{ matrix.arch }}-${{ matrix.target }}
           arch: ${{ matrix.arch }}
 
       - name: Build and Test Botan
-        run: python3 ./src/scripts/ci_build.py --cc='msvc' --make-tool='ninja' --cpu='${{ matrix.arch }}' --test-results-dir=junit_results ${{ matrix.target }}
+        run: python3 ./src/scripts/ci_build.py --cc='${{ matrix.compiler }}' --make-tool='ninja' --cpu='${{ matrix.arch }}' --test-results-dir=junit_results ${{ matrix.target }}
 
   linux:
     name: "Linux"

configure.py

@@ -2313,11 +2313,21 @@ def test_exe_extra_ldflags():
         variables['includedir'],
         'botan-%d' % (Version.major()), 'botan')
 
-    if cc.basename == 'msvc' and variables['cxx_abi_flags'] != '':
-        # MSVC linker doesn't support/need the ABI options,
-        # just transfer them over to just the compiler invocations
+    # On MSVC, the "ABI flags" should be passed to the compiler only, on other platforms, the
+    # ABI flags are passed to both the compiler and the linker and the compiler flags are also
+    # passed to the linker(?)
+    #
+    # TODO: Extend the build-data/cc/xxx.txt format to allow specifying different CFLAGS for
+    # different configurations, then /MD etc could be specified there rather than hijacking the ABI
+    # flags for it and having to special-case their exclusion from the linker command line.
+
+    if cc.basename in ('msvc', 'clangcl'):
+        # Move the "ABI flags" (/MD etc) into the compiler flags to exclude it from linker invocations
         variables['cc_compile_flags'] = '%s %s' % (variables['cxx_abi_flags'], variables['cc_compile_flags'])
         variables['cxx_abi_flags'] = ''
+    else:
+        # Append the compiler flags to the linker flags
+        variables['ldflags'] = '%s %s' % (variables['ldflags'], variables['cc_compile_flags'])
 
     variables['lib_flags'] = cc.gen_lib_flags(options, variables)
 
@@ -3277,11 +3287,11 @@ def validate_options(options, info_os, info_cc, available_module_policies):
         raise UserError('Option --with-pdf requires --with-sphinx')
 
     # Warnings
-    if options.os == 'windows' and options.compiler != 'msvc':
+    if options.os == 'windows' and options.compiler not in ('msvc', 'clangcl'):
         logging.warning('The windows target is oriented towards MSVC; maybe you want --os=cygwin or --os=mingw')
 
     if options.msvc_runtime:
-        if options.compiler != 'msvc':
+        if options.compiler not in ('msvc', 'clangcl'):
             raise UserError("Makes no sense to specify MSVC runtime for %s" % (options.compiler))
 
         if options.msvc_runtime not in ['MT', 'MD', 'MTd', 'MDd']:
@@ -3303,6 +3313,7 @@ def calculate_cc_min_version(options, ccinfo, source_paths):
         'msvc': r'^ *MSVC ([0-9]{2})([0-9]{2})$',
         'gcc': r'^ *GCC ([0-9]+) ([0-9]+)$',
         'clang': r'^ *CLANG ([0-9]+) ([0-9]+)$',
+        'clangcl': r'^ *CLANG ([0-9]+) ([0-9]+)$',
         'xcode': r'^ *XCODE ([0-9]+) ([0-9]+)$',
         'xlc': r'^ *XLC ([0-9]+) ([0-9]+)$',
         'emcc': r'^ *EMCC ([0-9]+) ([0-9]+)$',

src/build-data/cc/clangcl.txt

@@ -0,0 +1,102 @@
+macro_name CLANGCL
+
+minimum_supported_version 14.0
+
+binary_name clang-cl
+linker_name lld-link
+
+output_to_object "/Fo"
+output_to_exe "/OUT:"
+
+add_include_dir_option "/I"
+add_system_include_dir_option "/external:W0 /external:I"
+add_lib_dir_option "/LIBPATH:"
+add_compile_definition_option "/D"
+add_lib_option "%s.lib"
+
+compile_flags "/nologo /c"
+
+supports_gcc_inline_asm yes
+
+optimization_flags "/O2 /Oi"
+size_optimization_flags "/O1 /Os"
+
+# for debug info in the object file (required if using sccache):
+#debug_info_flags "/Z7"
+
+# for using a PDB file:
+debug_info_flags "/Zi /FS"
+
+preproc_flags "/nologo /EP"
+
+lang_flags "/std:c++20 /EHs /GR"
+
+# 4251: STL types used in DLL interface
+# 4275: ???
+# 5072: ASan without debug info
+warning_flags "/W4 /wd4251 /wd4275 /wd5072"
+
+werror_flags "/WX"
+
+visibility_build_flags "/DBOTAN_DLL=__declspec(dllexport)"
+visibility_attribute "__declspec(dllimport)"
+
+# Include dependency tracking for Ninja
+# See: https://ninja-build.org/manual.html#ref_headers
+ninja_header_deps_style 'msvc'
+header_deps_flag '/showIncludes'
+
+ar_command lib
+ar_options "/nologo"
+ar_output_to "/OUT:"
+
+<sanitizers>
+default -> address
+
+iterator -> "/D_ITERATOR_DEBUG_LEVEL=1"
+address   -> "/fsanitize=address"
+</sanitizers>
+
+<isa_flags>
+sse2   -> "-msse2"
+ssse3  -> "-mssse3"
+sse41  -> "-msse4.1"
+sse42  -> "-msse4.2"
+avx2   -> "-mavx2"
+avx512  -> "-mavx512f -mavx512bw -mavx512dq -mavx512vbmi -mavx512vbmi2 -mavx512bitalg -mavx512vl -mavx512ifma"
+
+bmi2   -> "-mbmi -mbmi2"
+aesni  -> "-maes -mpclmul"
+rdrand -> "-mrdrnd"
+rdseed -> "-mrdseed"
+sha    -> "-msha"
+altivec -> "-maltivec"
+
+arm64:armv8crypto -> "-march=armv8+crypto"
+arm64:armv8sha512 -> "-march=armv8.2-a+sha3"
+
+arm32:neon    -> "-mfpu=neon"
+arm64:neon    -> ""
+</isa_flags>
+
+<lib_flags>
+debug -> "/Fd%{build_dir}/%{libname}.pdb"
+</lib_flags>
+
+<so_link_commands>
+default       -> "{linker} /DLL"
+default-debug -> "{linker} /DLL /DEBUG"
+</so_link_commands>
+
+<binary_link_commands>
+default       -> "{linker}"
+default-debug -> "{linker} /DEBUG"
+</binary_link_commands>
+
+<mach_abi_linking>
+all              -> "/bigobj"
+
+# These can be overridden with --msvc-runtime option
+rt               -> "/MD"
+rt-debug         -> "/MDd"
+</mach_abi_linking>

src/build-data/detect_version.cpp

@@ -3,7 +3,7 @@
 * configure.py to determine the compilers version number.
 */
 
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) and !defined(__clang__)
 
 /*
    _MSC_VER Defined as an integer literal that encodes the major and

src/build-data/makefile.in

@@ -16,7 +16,7 @@ LANG_EXE_FLAGS = %{cc_lang_binary_linker_flags}
 CXXFLAGS       = %{cc_compile_flags}
 WARN_FLAGS     = %{cc_warning_flags}
 LIB_FLAGS      = %{lib_flags}
-LDFLAGS        = %{ldflags} %{cc_compile_flags}
+LDFLAGS        = %{ldflags}
 
 EXE_LINK_CMD   = %{exe_link_cmd}
 

src/build-data/ninja.in

@@ -10,7 +10,7 @@ LANG_EXE_FLAGS = %{cc_lang_binary_linker_flags}
 CXXFLAGS       = %{cc_compile_flags}
 WARN_FLAGS     = %{cc_warning_flags}
 
-LDFLAGS        = %{ldflags} %{cc_compile_flags}
+LDFLAGS        = %{ldflags}
 
 EXE_LINK_CMD   = %{exe_link_cmd}
 

src/lib/math/bigint/big_ops2.cpp

@@ -11,6 +11,20 @@
 #include <botan/internal/mp_core.h>
 #include <algorithm>
 
+/* This hack works around an undefined reference to __udivti3() when compiling for 64-bit Windows
+ * using clang-cl, see:
+ *
+ * https://github.com/llvm/llvm-project/issues/25679
+ * https://stackoverflow.com/questions/68676184/clang-cl-error-lld-link-error-undefined-symbol-divti3
+ *
+ * I couldn't come up with a way to embed this into the build info files without extending
+ * configure.py to allow cpu-specific libs in the compiler info or os+cc+arch-specific libs in the
+ * module info. Hopefully this can go away when the above Clang issue is fixed anyway.
+*/
+#if defined(_WIN64) && defined(BOTAN_BUILD_COMPILER_IS_CLANGCL)
+   #pragma comment(lib, "clang_rt.builtins-x86_64.lib")
+#endif
+
 namespace Botan {
 
 BigInt& BigInt::add(const word y[], size_t y_words, Sign y_sign) {

src/lib/prov/pkcs11/p11.h

@@ -24,7 +24,14 @@
    #define CK_DECLARE_FUNCTION(returnType, name) returnType name
 #endif
 
-#if defined(_MSC_VER)
+/* When building with clang-cl, specifying this with dllimport causes a warning when defining the
+ * CK_C_XXX function pointer types in pkcs11.h:
+ *
+ * 'dllimport' attribute only applies to functions, variables, classes, and Objective-C interfaces
+ *
+ * I'm not convinced the dllimport is needed/approproate for typedefs under MSVC either.
+*/
+#if 0  // defined(_MSC_VER)
    #define CK_DECLARE_FUNCTION_POINTER(returnType, name) returnType __declspec(dllimport)(*name)
 #else
    #define CK_DECLARE_FUNCTION_POINTER(returnType, name) returnType(*name)
@@ -40,7 +47,7 @@
    #pragma pack(push, cryptoki, 1)
 #endif
 
-#include "pkcs11.h"
+#include <pkcs11.h>
 
 #if defined(_MSC_VER)
    #pragma pack(pop, cryptoki)

src/lib/pubkey/dh/dh.h

@@ -78,7 +78,7 @@ BOTAN_DIAGNOSTIC_PUSH
 BOTAN_DIAGNOSTIC_IGNORE_INHERITED_VIA_DOMINANCE
 
 class BOTAN_PUBLIC_API(2, 0) DH_PrivateKey final : public DH_PublicKey,
-                                                   public PK_Key_Agreement_Key,
+                                                   public virtual PK_Key_Agreement_Key,
                                                    public virtual Private_Key {
    public:
       /**

src/lib/pubkey/ecdh/ecdh.h

@@ -66,8 +66,8 @@ BOTAN_DIAGNOSTIC_PUSH
 BOTAN_DIAGNOSTIC_IGNORE_INHERITED_VIA_DOMINANCE
 
 class BOTAN_PUBLIC_API(2, 0) ECDH_PrivateKey final : public ECDH_PublicKey,
-                                                     public EC_PrivateKey,
-                                                     public PK_Key_Agreement_Key {
+                                                     public virtual EC_PrivateKey,
+                                                     public virtual PK_Key_Agreement_Key {
    public:
       /**
       * Load a private key.

src/lib/pubkey/ecies/ecies.cpp

@@ -26,8 +26,8 @@ namespace {
 BOTAN_DIAGNOSTIC_PUSH
 BOTAN_DIAGNOSTIC_IGNORE_INHERITED_VIA_DOMINANCE
 
-class ECIES_PrivateKey final : public EC_PrivateKey,
-                               public PK_Key_Agreement_Key {
+class ECIES_PrivateKey final : public virtual EC_PrivateKey,
+                               public virtual PK_Key_Agreement_Key {
    public:
       explicit ECIES_PrivateKey(const ECDH_PrivateKey& private_key) :
             EC_PublicKey(private_key), EC_PrivateKey(private_key), PK_Key_Agreement_Key(), m_key(private_key) {}

src/lib/pubkey/rsa/rsa.h

@@ -98,8 +98,8 @@ class BOTAN_PUBLIC_API(2, 0) RSA_PublicKey : public virtual Public_Key {
 BOTAN_DIAGNOSTIC_PUSH
 BOTAN_DIAGNOSTIC_IGNORE_INHERITED_VIA_DOMINANCE
 
-class BOTAN_PUBLIC_API(2, 0) RSA_PrivateKey final : public Private_Key,
-                                                    public RSA_PublicKey {
+class BOTAN_PUBLIC_API(2, 0) RSA_PrivateKey final : public virtual Private_Key,
+                                                    public virtual RSA_PublicKey {
    public:
       /**
       * Load a private key.

src/lib/tls/tls13_pqc/hybrid_public_key.h

@@ -82,8 +82,8 @@ BOTAN_DIAGNOSTIC_IGNORE_INHERITED_VIA_DOMINANCE
  * Composes a number of private keys for hybrid key agreement as defined in this
  * IETF draft: https://datatracker.ietf.org/doc/html/draft-ietf-tls-hybrid-design-04
  */
-class BOTAN_TEST_API Hybrid_KEM_PrivateKey final : public Private_Key,
-                                                   public Hybrid_KEM_PublicKey {
+class BOTAN_TEST_API Hybrid_KEM_PrivateKey final : public virtual Private_Key,
+                                                   public virtual Hybrid_KEM_PublicKey {
    public:
       /**
        * Generate a hybrid private key for the given TLS code point.

src/lib/utils/os_utils.cpp

@@ -453,7 +453,8 @@ bool OS::read_env_variable(std::string& value_out, std::string_view name_view) {
       return false;
    }
 
-#if defined(BOTAN_TARGET_OS_HAS_WIN32) && defined(BOTAN_BUILD_COMPILER_IS_MSVC)
+#if defined(BOTAN_TARGET_OS_HAS_WIN32) && \
+   (defined(BOTAN_BUILD_COMPILER_IS_MSVC) || defined(BOTAN_BUILD_COMPILER_IS_CLANGCL))
    const std::string name(name_view);
    char val[128] = {0};
    size_t req_size = 0;

src/lib/utils/socket/socket.cpp

@@ -239,8 +239,7 @@ class BSD_Socket final : public OS::Socket {
                   struct timeval timeout_tv = make_timeout_tv();
                   fd_set write_set;
                   FD_ZERO(&write_set);
-                  // Weirdly, Winsock uses a SOCKET type but wants FD_SET to get an int instead
-                  FD_SET(static_cast<int>(m_socket), &write_set);
+                  FD_SET(m_socket, &write_set);
 
                   active = ::select(static_cast<int>(m_socket + 1), nullptr, &write_set, nullptr, &timeout_tv);
 

src/lib/x509/certstor_flatfile/certstor_flatfile.h

@@ -10,6 +10,7 @@
 #define BOTAN_CERT_STORE_FLATFILE_H_
 
 #include <botan/certstor.h>
+#include <botan/pkix_types.h>
 
 #include <map>
 #include <memory>

src/scripts/ci/setup_gh_actions.ps1

@@ -33,3 +33,8 @@ if($identifiers_for_64bit -contains $ARCH ) {
 }
 
 echo "SCCACHE_CACHE_SIZE=200M" >> $env:GITHUB_ENV
+
+# Remove standalone LLVM (and clang-cl) from PATH - we want to use the one shipped with VS.
+# https://github.com/actions/runner-images/issues/10001#issuecomment-2150541007
+$no_llvm_path = ($env:PATH -split ';' | Where-Object { $_ -ne 'C:\Program Files\LLVM\bin' }) -join ';'
+echo "PATH=$no_llvm_path" >> $env:GITHUB_ENV

src/scripts/ci_build.py

@@ -671,6 +671,8 @@ def main(args=None):
             options.cc_bin = 'clang++'
         elif options.cc == 'msvc':
             options.cc_bin = 'cl'
+        elif options.cc == 'clangcl':
+            options.cc_bin = 'clang-cl'
         elif options.cc == "emcc":
             options.cc_bin = "em++"
         else:

src/scripts/ci_check_install.py

@@ -27,7 +27,7 @@ def verify_library(build_config):
 
     major_version = int(build_config["version_major"])
 
-    if build_config['compiler'] == 'msvc':
+    if build_config['compiler'] in ['msvc', 'clangcl']:
         expected_lib_format = r'^botan-%d\.(dll|lib)$' % (major_version)
     elif build_config['os'] == 'macos':
         expected_lib_format = r'^libbotan-%d\.(a|dylib)$' % (major_version)

src/tests/runner/test_xml_reporter.cpp

@@ -51,6 +51,8 @@ std::string full_compiler_name_string() {
    return "xcode";
    #elif defined(BOTAN_BUILD_COMPILER_IS_CLANG)
    return "clang";
+   #elif defined(BOTAN_BUILD_COMPILER_IS_CLANGCL)
+   return "clangcl";
    #elif defined(BOTAN_BUILD_COMPILER_IS_GCC)
    return "gcc";
    #elif defined(BOTAN_BUILD_COMPILER_IS_MSVC)