Fix C23 empty initializers

These should should act as zero initializers, but since init==NULL
was used to mean both "no initializer" and "empty initializer",
empty initializers weren't zero-initializing the variable.

5 files changed, 13 insertions, 6 deletions

diff --git a/cc.h b/cc.h
index 860ca94..956e2e9 100644
--- a/cc.h
+++ b/cc.h
@@ -542,7 +542,7 @@ void funcjnz(struct func *, struct value *, struct type *, struct block *, struc
 void funcret(struct func *, struct value *);
 struct gotolabel *funcgoto(struct func *, char *);
 void funcswitch(struct func *, struct value *, struct switchcases *, struct block *);
-void funcinit(struct func *, struct decl *, struct init *);
+void funcinit(struct func *, struct decl *, struct init *, _Bool);
 
 void emitfunc(struct func *, _Bool);
 void emitdata(struct decl *,  struct init *);
diff --git a/decl.c b/decl.c
index 8ffc058..111c0e3 100644
--- a/decl.c
+++ b/decl.c
@@ -890,6 +890,7 @@ decl(struct scope *s, struct func *f)
 	enum storageclass sc;
 	enum funcspec fs;
 	struct init *init;
+	bool hasinit;
 	struct param *p;
 	char *name, *asmname;
 	int allowfunc = !f;
@@ -952,12 +953,14 @@ decl(struct scope *s, struct func *f)
 			if (d->u.obj.align < align)
 				d->u.obj.align = align;
 			init = NULL;
+			hasinit = false;
 			if (consume(TASSIGN)) {
 				if (f && d->linkage != LINKNONE)
 					error(&tok.loc, "object '%s' with block scope and %s linkage cannot have initializer", name, d->linkage == LINKEXTERN ? "external" : "internal");
 				if (d->defined)
 					error(&tok.loc, "object '%s' redefined", name);
 				init = parseinit(s, d->type);
+				hasinit = true;
 			} else if (d->linkage != LINKNONE) {
 				if (!(sc & SCEXTERN) && !d->defined && !d->u.obj.tentative.next)
 					listinsert(tentativedefns.prev, &d->u.obj.tentative);
@@ -966,7 +969,7 @@ decl(struct scope *s, struct func *f)
 			if (d->linkage != LINKNONE || sc & SCSTATIC)
 				emitdata(d, init);
 			else
-				funcinit(f, d, init);
+				funcinit(f, d, init, hasinit);
 			d->defined = true;
 			if (d->u.obj.tentative.next)
 				listremove(&d->u.obj.tentative);
diff --git a/qbe.c b/qbe.c
index cce245e..08d10b5 100644
--- a/qbe.c
+++ b/qbe.c
@@ -498,7 +498,7 @@ mkfunc(struct decl *decl, char *name, struct type *t, struct scope *s)
 			d->value = p->value;
 		} else {
 			v = typecompatible(p->type, pt) ? p->value : convert(f, pt, p->type, p->value);
-			funcinit(f, d, NULL);
+			funcalloc(f, d);
 			funcstore(f, p->type, QUALNONE, (struct lvalue){d->value}, v);
 		}
 		scopeputdecl(s, p->name, d);
@@ -640,7 +640,7 @@ funclval(struct func *f, struct expr *e)
 		break;
 	case EXPRCOMPOUND:
 		d = mkdecl(DECLOBJECT, e->type, e->qual, LINKNONE);
-		funcinit(f, d, e->u.compound.init);
+		funcinit(f, d, e->u.compound.init, true);
 		lval.addr = d->value;
 		break;
 	case EXPRUNARY:
@@ -931,7 +931,7 @@ zero(struct func *func, struct value *addr, int align, unsigned long long offset
 }
 
 void
-funcinit(struct func *func, struct decl *d, struct init *init)
+funcinit(struct func *func, struct decl *d, struct init *init, bool hasinit)
 {
 	struct lvalue dst;
 	struct value *src, *v;
@@ -939,7 +939,7 @@ funcinit(struct func *func, struct decl *d, struct init *init)
 	size_t i, w;
 
 	funcalloc(func, d);
-	if (!init)
+	if (!hasinit)
 		return;
 	for (; init; init = init->next) {
 		zero(func, d->value, d->type->align, offset, init->start);
diff --git a/test/initializer-empty-struct.qbe b/test/initializer-empty-struct.qbe
index 9bbfb34..400f504 100644
--- a/test/initializer-empty-struct.qbe
+++ b/test/initializer-empty-struct.qbe
@@ -4,5 +4,8 @@ function $f() {
 @start.1
 	%.1 =l alloc8 16
 @body.2
+	storel 0, %.1
+	%.2 =l add %.1, 8
+	storel 0, %.2
 	ret
 }
diff --git a/test/initializer-empty.qbe b/test/initializer-empty.qbe
index 2ed8249..f3358bd 100644
--- a/test/initializer-empty.qbe
+++ b/test/initializer-empty.qbe
@@ -4,5 +4,6 @@ function $f() {
 @start.1
 	%.1 =l alloc4 4
 @body.2
+	storew 0, %.1
 	ret
 }