fix cross compilation to a Windows target

Cross compilation of ECL itself:

- The windres program comes with the usual cross compilation target
  prefixes, use AC_CHECK_TOOL to select the right one.
- For c::update-compiler-features, we need to check the features of the
  host system instead of the target because that determines the
  executable prefix of the ecl_min stub.

Cross compilation of user code: We just have to replace some read time
conditionals by runtime checks.

Further notes on Windows cross compilation using mingw:

- Our old copy of libgmp doesn't work, one needs to update that before
  compiling.
- ASDF fails to compile unless XDG_CACHE_HOME is set (it tries and
  fails to find a Windows cache directory if XDG_CACHE_HOME is empty).
- The `windres` program may be located in a separate package from the
  mingw compiler. On debian, I had to install binutils-mingw-w64 and
  gcc-mingw-w64.

src/aclocal.m4

@@ -447,8 +447,10 @@ case "${host_os}" in
                 ECL_ADD_FEATURE([win32])
                 ECL_ADD_FEATURE([windows])
                 if test "x$host_cpu" = "xx86_64" ; then
-		   ECL_ADD_FEATURE([win64])
+                  ECL_ADD_FEATURE([win64])
                 fi
+                AC_CHECK_TOOL([WINDRES],[windres]) # set variable WINDRES to appropriate `windres' program
+                AC_SUBST(WINDRES)
                 ;;
         darwin*)
                 thehost='darwin'

src/cmp/cmpbackend-cxx/cmpbackend-cxx.lsp

@@ -375,8 +375,8 @@ filesystem or in the database of ASDF modules."
                     (list (concatenate 'string "/LIBPATH:"
                                        (ecl-library-directory))
                           (concatenate 'string "/IMPLIB:" implib)))))
-    #+mingw32
-    (setf ld-flags (list* "-shared" ld-flags))
+    (when (member :mingw32 *features*)
+      (setf ld-flags (list* "-shared" ld-flags)))
     (linker-cc o-pathname object-files :type :dll
                :ld-flags ld-flags :ld-libs ld-libs)))
 
@@ -399,8 +399,8 @@ filesystem or in the database of ASDF modules."
                      (concatenate 'string "/LIBPATH:"
                                   (ecl-library-directory))
                      (concatenate 'string "/IMPLIB:" implib)))))
-    #+mingw32
-    (setf ld-flags (list* "-shared" "-Wl,--export-all-symbols" ld-flags))
+    (when (member :mingw32 *features*)
+      (setf ld-flags (list* "-shared" "-Wl,--export-all-symbols" ld-flags)))
     (linker-cc o-pathname object-files :type :fasl
                                        :ld-flags ld-flags :ld-libs ld-libs)))
 
@@ -508,7 +508,6 @@ extern int
 }
 ")
 
-#+:win32
 (defconstant +lisp-program-winmain+ "
 #include <windows.h>
 int
@@ -570,7 +569,7 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdS
                   (main-name nil)
                   (prologue-code "")
                   (epilogue-code (when (eq target :program) '(SI::TOP-LEVEL T)))
-                  #+:win32 (system :console)
+                  (system :console)
                   &aux
                     (*suppress-compiler-messages* (or *suppress-compiler-messages*
                                                       (not *compile-verbose*)))
@@ -678,10 +677,9 @@ output = si_safe_eval(2, ecl_read_from_cstring(lisp_code), ECL_NIL);
          ;; we don't need wrapper in the program, we have main for that
                                         ;(format c-file +lisp-init-wrapper+ wrap-name init-name)
          (format c-file
-                 #+:win32 (ecase system
-                            (:console +lisp-program-main+)
-                            (:windows +lisp-program-winmain+))
-                 #-:win32 +lisp-program-main+
+                 (ecase system
+                   (:console +lisp-program-main+)
+                   (:windows +lisp-program-winmain+))
                  prologue-code init-name epilogue-code)
          (close c-file)
          (compiler-cc c-name o-name)

src/cmp/cmpbackend-cxx/cmppass2-data.lsp

@@ -59,19 +59,18 @@
 (defun data-c-dump (filename)
   (labels ((produce-strings ()
              ;; Only Windows has a size limit in the strings it creates.
-             #-windows
-             (let ((s (data-dump-array)))
-               (when (plusp (length s))
-                 (list s)))
-             #+windows
-             (loop with string = (data-dump-array)
-                   with max-string-size = 65530
-                   with l = (length string)
-                   for i from 0 below l by max-string-size
-                   for this-l = (min (- l i) max-string-size)
-                   collect (make-array this-l :displaced-to string
-                                              :element-type (array-element-type string)
-                                              :displaced-index-offset i)))
+             (if (member :windows *features*)
+                 (loop with string = (data-dump-array)
+                       with max-string-size = 65530
+                       with l = (length string)
+                       for i from 0 below l by max-string-size
+                       for this-l = (min (- l i) max-string-size)
+                       collect (make-array this-l :displaced-to string
+                                           :element-type (array-element-type string)
+                                           :displaced-index-offset i))
+                 (let ((s (data-dump-array)))
+                   (when (plusp (length s))
+                     (list s)))))
            (output-one-c-string (name string stream)
              (let* ((*wt-string-size* 0)
                     (*wt-data-column* 80)

src/compile.lsp.in

@@ -18,7 +18,8 @@
   (setq *features* '(@LSP_FEATURES@ @COMPILATION_FEATURES@))
   (when (member :ecl-min *host-features*)
     (setq *features* (cons :ecl-min *features*)))
-  (when (member :uname *host-features*)
+  (when (and (member :uname *host-features*)
+             (not (member :windows *features*)))
     (setq *features* (cons :uname *features*)))
   (when (member :cross *host-features*)
     (setq *features* (cons :cross *features*))))
@@ -41,8 +42,9 @@
 (progn
   (c::update-compiler-features
    :executable
-   #+(or windows cygwin mingw32) "build:ecl_min.exe"
-   #-(or windows cygwin mingw32) "build:@ECL_MIN@")
+   (if (intersection '(:windows :cygwin :mingw32) *host-features*)
+       "build:ecl_min.exe"
+       "build:@ECL_MIN@"))
   (format t "~&;;; System features: ~A~%" c::*compiler-features*))
 
 ;;;
@@ -375,7 +377,7 @@
   (write-line "id ICON \"ecl.ico\"" s))
  (ext:copy-file #p"src:util;ecl.ico" "ecl.ico")
  #+msvc (ext:system "rc /nologo /r ecl.rc")
- #-msvc (ext:system "windres ecl.rc -O coff ecl.res"))
+ #-msvc (ext:system "@WINDRES@ ecl.rc -O coff ecl.res"))
 
 (si::pathname-translations "SYS" '(("**;*.*.*" "@true_builddir@/**/*.*")))