From 27e3cf0dedb657fe92c1c6928beb3d7882292262 Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Thu, 30 Jan 2020 13:20:54 -0800
Subject: decl: Use list link to determine presence in tentative definition
 list

---
 cc.h   | 10 +++++-----
 decl.c | 18 ++++++------------
 util.c |  1 +
 3 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/cc.h b/cc.h
index 4054dcd..47a2931 100644
--- a/cc.h
+++ b/cc.h
@@ -255,13 +255,13 @@ struct decl {
 	struct type *type;
 	enum typequal qual;
 	struct value *value;
+	_Bool defined;
 
-	/* objects and functions */
-	struct list link;
-	int align;  /* may be more strict than type requires */
-	_Bool tentative, defined;
+	/* link in list of tentative object definitions */
+	struct list tentative;
+	/* alignment of object storage (may be stricter than type requires) */
+	int align;
 
-	/* built-ins */
 	enum builtinkind builtin;
 };
 
diff --git a/decl.c b/decl.c
index 9013a09..26e9851 100644
--- a/decl.c
+++ b/decl.c
@@ -65,14 +65,11 @@ mkdecl(enum declkind k, struct type *t, enum typequal tq, enum linkage linkage)
 	struct decl *d;
 
 	d = xmalloc(sizeof(*d));
+	memset(d, 0, sizeof(*d));
 	d->kind = k;
 	d->linkage = linkage;
 	d->type = t;
 	d->qual = tq;
-	d->tentative = false;
-	d->defined = false;
-	d->align = 0;
-	d->value = NULL;
 
 	return d;
 }
@@ -971,13 +968,10 @@ decl(struct scope *s, struct func *f)
 				else
 					funcinit(f, d, init);
 				d->defined = true;
-				if (d->tentative) {
-					d->tentative = false;
-					listremove(&d->link);
-				}
-			} else if (!(sc & SCEXTERN) && !d->defined && !d->tentative) {
-				d->tentative = true;
-				listinsert(tentativedefns.prev, &d->link);
+				if (d->tentative.next)
+					listremove(&d->tentative);
+			} else if (!(sc & SCEXTERN) && !d->defined && !d->tentative.next) {
+				listinsert(tentativedefns.prev, &d->tentative);
 			}
 			break;
 		case DECLFUNC:
@@ -1053,5 +1047,5 @@ emittentativedefns(void)
 	struct list *l;
 
 	for (l = tentativedefns.next; l != &tentativedefns; l = l->next)
-		emitdata(listelement(l, struct decl, link), NULL);
+		emitdata(listelement(l, struct decl, tentative), NULL);
 }
diff --git a/util.c b/util.c
index 1e44194..1229f2c 100644
--- a/util.c
+++ b/util.c
@@ -130,4 +130,5 @@ listremove(struct list *list)
 {
 	list->next->prev = list->prev;
 	list->prev->next = list->next;
+	list->next = list->prev = NULL;
 }
-- 
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