From a19fd1f871d1f348e505069f38e98be030653fcf Mon Sep 17 00:00:00 2001
From: Stas Sergeev <stsp2@yandex.ru>
Date: Tue, 6 Feb 2024 15:48:32 +0500
Subject: [PATCH] restore compatibility with older clang

---
 fdpp/clang.mak   |  3 ++-
 fdpp/farptr.hpp  | 10 ++++++++++
 fdpp/meson.build |  3 ++-
 hdr/process.h    |  2 +-
 4 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/fdpp/clang.mak b/fdpp/clang.mak
index 8e61aeae..de71b332 100644
--- a/fdpp/clang.mak
+++ b/fdpp/clang.mak
@@ -24,7 +24,8 @@ endif
 NASM ?= nasm-segelf
 PKG_CONFIG ?= pkg-config
 
-TARGETOPT = -std=c++20 -c -fno-threadsafe-statics -fpic
+TARGETOPT = -std=c++20 -c -fno-threadsafe-statics -fpic \
+  -DCLANG_VER=$(CLANG_VER)
 # _XTRA should go at the end of cmd line
 TARGETOPT_XTRA = -Wno-format-invalid-specifier -Wno-c99-designator
 
diff --git a/fdpp/farptr.hpp b/fdpp/farptr.hpp
index 5192689c..9d5332c3 100644
--- a/fdpp/farptr.hpp
+++ b/fdpp/farptr.hpp
@@ -754,14 +754,24 @@ class SymMembT : public MembBase<T, P, M, O> {
 #define __ASMCALL(f) AsmCSym f
 #define __ASYM(x) x.get_sym()
 #define ASMREF(t) AsmRef<t>
+#if CLANG_VER < 14
+#define DUMMY_MARK(p, n) \
+    static constexpr int off_##n(void) { return offsetof(p, n); }
+#define OFF_M(p, n) p::off_##n
+#else
+#define DUMMY_MARK(p, n)
 #define OFF_M(p, n) []<typename T = p>() constexpr { return offsetof(T, n); }
+#endif
 #define AR_MEMB(p, t, n, l) \
+    DUMMY_MARK(p, n); \
     ArMemb<t, l, p, OFF_M(p, n)> n
 #define SYM_MEMB(p, t, n) \
+    DUMMY_MARK(p, n); \
     SymMemb<t, p, OFF_M(p, n)> n
 #define SYM_MEMB2(p, m, o, t, n) \
     SymMemb<t, p, OFF_M(p, m), o> n
 #define SYM_MEMB_T(p, t, n) \
+    DUMMY_MARK(p, n); \
     SymMembT<t, p, OFF_M(p, n)> n
 #define FP_SEG(fp) ((fp).seg())
 #define FP_OFF(fp) ((fp).off())
diff --git a/fdpp/meson.build b/fdpp/meson.build
index f425c70d..f943cf40 100644
--- a/fdpp/meson.build
+++ b/fdpp/meson.build
@@ -138,11 +138,12 @@ FDPP_CCFILES = ['thunks.cc', 'thunks_c.cc', 'thunks_a.cc', 'thunks_p.cc',
 CPPFILES = ['objhlp.cpp', 'ctors.cpp', 'farhlp.cpp', 'objtrace.cpp']
 hdr = ['src', 'hdr', '.', rel_inc]
 incdir2 = include_directories(hdr)
+CLANG_VER = meson.get_compiler('cpp').version().split('.')[0]
 LIBFDPP = shared_library('fdpp', [ccfiles, ppccf, FDPP_CCFILES, CPPFILES],
   include_directories: incdir2,
   version: FVER,
   sources: [gad, pac, pap, tc, ta],
-  cpp_args: ['-DFDPP', '-DDEBUG', '-DWITHFAT32',
+  cpp_args: ['-DFDPP', '-DDEBUG', '-DWITHFAT32', '-DCLANG_VER=' + CLANG_VER,
       '-fno-threadsafe-statics',
       '-Werror=packed-non-pod', '-Wno-unknown-warning-option',
       '-Wno-format-invalid-specifier', '-Wno-c99-designator'
diff --git a/hdr/process.h b/hdr/process.h
index a18aeb31..227d87a8 100644
--- a/hdr/process.h
+++ b/hdr/process.h
@@ -90,7 +90,7 @@ typedef struct _psp {
   UBYTE ps_fill2c[7];           /* 49 unused, 7 bytes              */
   UBYTE ps_unix[3];             /* 50 unix style call - 0xcd 0x21 0xcb */
   BYTE ps_fill3[9];             /* 53 */
-//  DUMMY_MARK(_psp, _u);
+  DUMMY_MARK(_psp, _u);
   union {
     struct {
       SYM_MEMB2(_psp, _u, 0, fcb, _ps_fcb1);             /* 5c first command line argument */