Add SWIFT_STDLIB_EXTRA_SWIFT_COMPILE_FLAGS and SWIFT_STDLIB_EXTRA_C_COMPILE_FLAGS CMake options (#40171)

Author: kubamracek

stdlib/CMakeLists.txt

@@ -75,6 +75,12 @@ endif()
 # NOTE: Some of these variables are also initialized in StandaloneOverlay.cmake
 # so that interfaces are emitted when overlays are separately built.
 
+set(SWIFT_STDLIB_EXTRA_SWIFT_COMPILE_FLAGS "" CACHE STRING
+    "Extra flags to pass when compiling swift stdlib files")
+
+set(SWIFT_STDLIB_EXTRA_C_COMPILE_FLAGS "" CACHE STRING
+    "Extra flags to pass when compiling C/C++ stdlib files")
+
 option(SWIFT_STDLIB_STABLE_ABI
        "Should stdlib be built with stable ABI (library evolution, resilience)."
        "${SWIFT_STDLIB_STABLE_ABI_default}")

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -367,6 +367,8 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-DSWIFT_STDLIB_SUPPORTS_BACKTRACE_REPORTING")
   endif()
 
+  list(APPEND result ${SWIFT_STDLIB_EXTRA_C_COMPILE_FLAGS})
+
   set("${CFLAGS_RESULT_VAR_NAME}" "${result}" PARENT_SCOPE)
 endfunction()
 

stdlib/cmake/modules/SwiftSource.cmake

@@ -506,6 +506,8 @@ function(_compile_swift_files
     list(APPEND swift_flags "-experimental-hermetic-seal-at-link")
   endif()
 
+  list(APPEND swift_flags ${SWIFT_STDLIB_EXTRA_SWIFT_COMPILE_FLAGS})
+
   list(APPEND swift_flags ${SWIFT_EXPERIMENTAL_EXTRA_FLAGS})
 
   if(SWIFTFILE_OPT_FLAGS)