fix: patch WAMR win_file.c trailing backslashes that break Windows build

WAMR 2.4.4 win_file.c has three comments ending with backslash +
trailing whitespace, which clang treats as line continuations,
swallowing the next line of code and causing compile errors.

Replace the previous -Wno-backslash-newline-escape workaround (which
only suppressed the warning, not the parse error) with a proper git
patch applied between FetchContent_Populate and add_subdirectory.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: raphaelcoeffic

cmake/FetchWamr.cmake

@@ -24,10 +24,21 @@ FetchContent_Declare(
   GIT_SHALLOW    TRUE
 )
 
-FetchContent_MakeAvailable(wamr)
+# Populate separately so we can patch before building
+FetchContent_GetProperties(wamr)
+if(NOT wamr_POPULATED)
+  FetchContent_Populate(wamr)
 
-# WAMR 2.4.4 win_file.c has trailing backslashes in comments that
-# clang treats as line continuations, causing compile errors.
-if(WIN32)
-  target_compile_options(vmlib PRIVATE -Wno-backslash-newline-escape)
+  # WAMR 2.4.4 win_file.c has trailing backslashes in comments that
+  # clang treats as line continuations, causing compile errors.
+  execute_process(
+    COMMAND git apply "${CMAKE_CURRENT_LIST_DIR}/wamr-fix-win-backslash-comments.patch"
+    WORKING_DIRECTORY "${wamr_SOURCE_DIR}"
+    RESULT_VARIABLE _patch_result
+  )
+  if(_patch_result)
+    message(WARNING "WAMR win_file.c patch failed (may already be applied)")
+  endif()
+
+  add_subdirectory("${wamr_SOURCE_DIR}" "${wamr_BINARY_DIR}")
 endif()

cmake/wamr-fix-win-backslash-comments.patch

@@ -0,0 +1,29 @@
+diff --git a/core/shared/platform/windows/win_file.c b/core/shared/platform/windows/win_file.c
+index 55ea77a..ae14b1a 100644
+--- a/core/shared/platform/windows/win_file.c
++++ b/core/shared/platform/windows/win_file.c
+@@ -1295,13 +1295,13 @@ os_readlinkat(os_file_handle handle, const char *path, char *buf,
+ 
+         if (wbufsize >= 4 && wbuf[0] == L'\\' && wbuf[1] == L'?'
+             && wbuf[2] == L'?' && wbuf[3] == L'\\') {
+-            // Starts with \??\ 
++            // Has \??\ prefix
+             if (wbufsize >= 6
+                 && ((wbuf[4] >= L'A' && wbuf[4] <= L'Z')
+                     || (wbuf[4] >= L'a' && wbuf[4] <= L'z'))
+                 && wbuf[5] == L':' && (wbufsize == 6 || wbuf[6] == L'\\'))
+                 {
+-                    // \??\<drive>:\ 
++                    // \??\<drive>:\ path
+                     wbuf += 4;
+                     wbufsize -= 4;
+                 }
+@@ -1310,7 +1310,7 @@ os_readlinkat(os_file_handle handle, const char *path, char *buf,
+                          && (wbuf[6] == L'C' || wbuf[6] == L'c')
+                          && wbuf[7] == L'\\')
+                 {
+-                    // \??\UNC\<server>\<share>\ - make sure the final path looks like \\<server>\<share>\ 
++                    // \??\UNC\<server>\<share>\ - make sure the final path looks like \\<server>\<share>
+                     wbuf += 6;
+                     wbuf[0] = L'\\';
+                     wbufsize -= 6;