build-exe allows direct export of WinMainCRTStartup

Author: andrewrk

src/all_types.hpp

@@ -1455,6 +1455,7 @@ struct CodeGen {
     bool have_pub_main;
     bool have_c_main;
     bool have_winmain;
+    bool have_winmain_crt_startup;
     bool have_pub_panic;
     Buf *libc_lib_dir;
     Buf *libc_static_lib_dir;

src/analyze.cpp

@@ -3196,6 +3196,10 @@ ImportTableEntry *add_source_file(CodeGen *g, PackageTableEntry *package, Buf *a
                 g->have_winmain = true;
                 g->windows_subsystem_windows = true;
                 g->windows_subsystem_console = false;
+            } else if (proto_node->data.fn_proto.visib_mod == VisibModExport &&
+                buf_eql_str(proto_name, "WinMainCRTStartup") && g->zig_target.os == ZigLLVM_Win32)
+            {
+                g->have_winmain_crt_startup = true;
             }
 
         }

src/codegen.cpp

@@ -5213,7 +5213,8 @@ static void gen_root_source(CodeGen *g) {
     assert(g->root_out_name);
     assert(g->out_type != OutTypeUnknown);
 
-    if (!g->is_test_build && g->zig_target.os != ZigLLVM_UnknownOS && !g->have_c_main && !g->have_winmain &&
+    if (!g->is_test_build && g->zig_target.os != ZigLLVM_UnknownOS &&
+        !g->have_c_main && !g->have_winmain && !g->have_winmain_crt_startup &&
         ((g->have_pub_main && g->out_type == OutTypeObj) || g->out_type == OutTypeExe))
     {
         g->bootstrap_import = add_special_code(g, create_bootstrap_pkg(g, g->root_package), "bootstrap.zig");