From 8ec7e1225b783f66f6c233918a64d598fa392611 Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Mon, 17 Jul 2017 07:54:48 +0200
Subject: [PATCH] mescc: Tinycc support: sizeof struct field.

* module/language/c99/compiler.mes (expr->accu): Sizeof struct field.
* scaffold/tests/72-typedef-struct-def.c (test): Test it.
---
 module/language/c99/compiler.mes       | 12 ++++++++++++
 scaffold/tests/72-typedef-struct-def.c |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/module/language/c99/compiler.mes b/module/language/c99/compiler.mes
index cf0c56ea..b74be83a 100644
--- a/module/language/c99/compiler.mes
+++ b/module/language/c99/compiler.mes
@@ -511,6 +511,11 @@
                 (size (ast-type->size info type)))
            (append-text info (wrap-as (i386:value->accu size)))))
 
+        ((sizeof-expr (i-sel (ident ,field) (p-expr (ident ,array))))
+         (let* ((type (ident->type info array))
+                (size (field-size info type field)))
+           (append-text info (wrap-as (i386:value->accu size)))))
+
         ((sizeof-type (type-name (decl-spec-list (type-spec (fixed-type ,name)))))
          (let* ((type name)
                 (size (ast-type->size info type)))
@@ -1040,6 +1045,13 @@
                (prefix (and=> (member field (reverse fields) (lambda (a b) (equal? a (car b)))) cdr)))
           (apply + (map field:size prefix))))))
 
+(define (field-size info struct field)
+  (let ((xtype (ast-type->type info struct)))
+    (if (eq? (type:type xtype) 'union) 0
+        (let* ((fields (type:description xtype))
+               (field (and=> (member field fields (lambda (a b) (equal? a (car b)))) car)))
+          (field:size field)))))
+
 (define (ast->type o)
   (pmatch o
     ((fixed-type ,type)
diff --git a/scaffold/tests/72-typedef-struct-def.c b/scaffold/tests/72-typedef-struct-def.c
index 73ff7356..b6565cc7 100644
--- a/scaffold/tests/72-typedef-struct-def.c
+++ b/scaffold/tests/72-typedef-struct-def.c
@@ -54,5 +54,7 @@ test ()
   (*pp)->i = 3;
   printf ("(*pp)->i=%d\n", b.i);
 
+  printf ("sizeof i:%d\n", sizeof (p->i));
+
   return 0;
 }