mescc: Initialize missing struct fields to 0.

This is a follow-up to commits
    7a8a2fc517
    mescc: x86_64 support: Refactor to abstracted assembly, add x86_64.

and

    c9ba7a619b
    mescc: Refactor variable declaration.

There was a debug "22" leaking in compile.scm.  It should be a "0".

* module/mescc/compile.scm (init-local): Replace "22" with "0".
* lib/tests/scaffold/7v-struct-initialize-zeroes.c: New test.
* build-aux/check-mescc.sh (tcc_tests): Add it.
(xfail-tests): Remove lib/tests/scaffold/72-typedef-struct-def-local.c.

build-aux/check-mescc.sh

@@ -3,6 +3,7 @@
 # GNU Mes --- Maxwell Equations of Software
 # Copyright © 2017,2018,2019,2020,2022,2023 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 # Copyright © 2023 Andrius Štikonas <andrius@stikonas.eu>
+# Copyright © 2023 Ekaitz Zarraga <ekaitz@elenq.tech>
 #
 # This file is part of GNU Mes.
 #
@@ -195,6 +196,7 @@ lib/tests/scaffold/7u-inc-byte-word.c
 lib/tests/scaffold/7u-struct-func.c
 lib/tests/scaffold/7u-struct-size10.c
 lib/tests/scaffold/7u-vstack.c
+lib/tests/scaffold/7v-struct-initialize-zeroes.c
 lib/tests/scaffold/70-array-in-struct-init.c
 lib/tests/scaffold/70-struct-short-enum-init.c
 lib/tests/scaffold/70-struct-post.c
@@ -250,7 +252,6 @@ if test $compiler = mescc; then
 lib/tests/scaffold/17-compare-unsigned-char-le.c
 lib/tests/scaffold/17-compare-unsigned-short-le.c
 lib/tests/scaffold/66-local-char-array.c
-lib/tests/scaffold/72-typedef-struct-def-local.c
 lib/tests/scaffold/70-ternary-arithmetic-argument.c
 lib/tests/mes/90-abtod.c
 lib/tests/mes/90-dtoab.c

lib/tests/scaffold/7v-struct-initialize-zeroes.c

@@ -0,0 +1,41 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2023 Ekaitz Zarraga <ekaitz@elenq.tech>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+struct A
+{
+  int a;
+  int b;
+  int c;
+};
+
+
+int
+main ()
+{
+  struct A x = {0};
+  if (x.a != 0)
+    return 1;
+  if (x.b != 0)
+    return 2;
+  if (x.c != 0)
+    return 3;
+
+  return 0;
+}

module/mescc/compile.scm

@@ -2177,7 +2177,7 @@
                             (let* ((missing (max 0 (- (length field+counts) (length inits))))
                                    (counts (map cdr field+counts))
                                    (fields (map car field+counts))
-                                   (info (fold (cut init-struct-field local <> <> <> <>) info fields counts (append inits (map (const '(p-expr (fixed "22"))) (iota missing))))))
+                                   (info (fold (cut init-struct-field local <> <> <> <>) info fields counts (append inits (map (const '(p-expr (fixed "0"))) (iota missing))))))
                               ;; bah, loopme!
                               ;;(loop (list-tail field+counts (length field-fields)) (list-tail inits (length field-inits)) info)
                               info)))))))