Fix type-checking of va_list arguments to varargs built-ins

If the argument was a function parameter, its type has already been
adjusted. So on x86_64, we can't just ignore the automatic
array-to-pointer conversion, since it was never a pointer to begin
with.

Instead, keep track of the adjusted va_list type, and check that
the arguments to varargs built-ins match that type.

5 files changed, 36 insertions, 28 deletions

diff --git a/cc.h b/cc.h
index c4dbee9..396a4ae 100644
--- a/cc.h
+++ b/cc.h
@@ -415,6 +415,7 @@ struct type *typecomposite(struct type *, struct type *);
 struct type *typeunqual(struct type *, enum typequal *);
 struct type *typecommonreal(struct type *, unsigned, struct type *, unsigned);
 struct type *typepromote(struct type *, unsigned);
+struct type *typeadjust(struct type *);
 enum typeprop typeprop(struct type *);
 struct member *typemember(struct type *, const char *, uint64_t *);
 
@@ -428,6 +429,7 @@ extern struct type typeint, typeuint;
 extern struct type typelong, typeulong;
 extern struct type typellong, typeullong;
 extern struct type typefloat, typedouble, typeldouble;
+extern struct type *typeadjvalist;
 
 /* targ */
 
diff --git a/decl.c b/decl.c
index 8b5bfad..de129d5 100644
--- a/decl.c
+++ b/decl.c
@@ -618,21 +618,6 @@ declarator(struct scope *s, struct qualtype base, char **name, bool allowabstrac
 	return base;
 }
 
-static struct type *
-adjust(struct type *t)
-{
-	switch (t->kind) {
-	case TYPEARRAY:
-		t = mkpointertype(t->base, t->qual);
-		break;
-	case TYPEFUNC:
-		t = mkpointertype(t, QUALNONE);
-		break;
-	}
-
-	return t;
-}
-
 static struct param *
 parameter(struct scope *s)
 {
@@ -647,7 +632,7 @@ parameter(struct scope *s)
 		error(&tok.loc, "parameter declaration has invalid storage-class specifier");
 	t = declarator(s, t, &name, true);
 
-	return mkparam(name, adjust(t.type), t.qual);
+	return mkparam(name, typeadjust(t.type), t.qual);
 }
 
 static bool
@@ -669,7 +654,7 @@ paramdecl(struct scope *s, struct param *params)
 			;
 		if (!p)
 			error(&tok.loc, "old-style function declarator has no parameter named '%s'", name);
-		p->type = adjust(t.type);
+		p->type = typeadjust(t.type);
 		p->qual = t.qual;
 		if (tok.kind == TSEMICOLON)
 			break;
diff --git a/expr.c b/expr.c
index 1c91556..323cbb7 100644
--- a/expr.c
+++ b/expr.c
@@ -642,31 +642,31 @@ builtinfunc(struct scope *s, enum builtinkind kind)
 	case BUILTINVAARG:
 		e = mkexpr(EXPRBUILTIN, NULL);
 		e->builtin.kind = BUILTINVAARG;
-		e->base = mkunaryexpr(TBAND, assignexpr(s));
-		if (e->base->base->type != targ->typevalist)
+		e->base = assignexpr(s);
+		if (!typesame(e->base->type, typeadjvalist))
 			error(&tok.loc, "va_arg argument must have type va_list");
+		if (!e->base->decayed)
+			e->base = mkunaryexpr(TBAND, e->base);
 		expect(TCOMMA, "after va_list");
 		e->type = typename(s, &e->qual);
 		break;
 	case BUILTINVACOPY:
 		e = mkexpr(EXPRASSIGN, &typevoid);
 		e->assign.l = assignexpr(s);
+		if (!typesame(e->assign.l->type, typeadjvalist))
+			error(&tok.loc, "va_copy destination must have type va_list");
 		if (e->assign.l->decayed)
 			e->assign.l = e->assign.l->base;
-		if (e->assign.l->type != targ->typevalist)
-			error(&tok.loc, "va_copy destination must have type va_list");
 		expect(TCOMMA, "after target va_list");
 		e->assign.r = assignexpr(s);
+		if (!typesame(e->assign.r->type, typeadjvalist))
+			error(&tok.loc, "va_copy source must have type va_list");
 		if (e->assign.r->decayed)
 			e->assign.r = e->assign.r->base;
-		if (e->assign.r->type != targ->typevalist)
-			error(&tok.loc, "va_copy source must have type va_list");
 		break;
 	case BUILTINVAEND:
 		e = assignexpr(s);
-		if (e->decayed)
-			e = e->base;
-		if (e->type != targ->typevalist)
+		if (!typesame(e->type, typeadjvalist))
 			error(&tok.loc, "va_end argument must have type va_list");
 		e = mkexpr(EXPRBUILTIN, &typevoid);
 		e->builtin.kind = BUILTINVAEND;
@@ -674,9 +674,11 @@ builtinfunc(struct scope *s, enum builtinkind kind)
 	case BUILTINVASTART:
 		e = mkexpr(EXPRBUILTIN, &typevoid);
 		e->builtin.kind = BUILTINVASTART;
-		e->base = mkunaryexpr(TBAND, assignexpr(s));
-		if (e->base->base->type != targ->typevalist)
+		e->base = assignexpr(s);
+		if (!typesame(e->base->type, typeadjvalist))
 			error(&tok.loc, "va_start argument must have type va_list");
+		if (!e->base->decayed)
+			e->base = mkunaryexpr(TBAND, e->base);
 		expect(TCOMMA, "after va_list");
 		param = assignexpr(s);
 		if (param->kind != EXPRIDENT)
diff --git a/targ.c b/targ.c
index f2be127..6e89c51 100644
--- a/targ.c
+++ b/targ.c
@@ -55,4 +55,5 @@ targinit(const char *name)
 	if (!targ)
 		fatal("unknown target '%s'", name);
 	typechar.basic.issigned = targ->signedchar;
+	typeadjvalist = typeadjust(targ->typevalist);
 }
diff --git a/type.c b/type.c
index 1d28213..2653310 100644
--- a/type.c
+++ b/type.c
@@ -39,6 +39,8 @@ struct type typefloat   = FLTTYPE(TYPEFLOAT, 4);
 struct type typedouble  = FLTTYPE(TYPEDOUBLE, 8);
 struct type typeldouble = FLTTYPE(TYPELDOUBLE, 16);
 
+struct type *typeadjvalist;
+
 struct type *
 mktype(enum typekind kind, enum typeprop prop)
 {
@@ -216,6 +218,22 @@ typecommonreal(struct type *t1, unsigned w1, struct type *t2, unsigned w2)
 	fatal("internal error; could not find common real type");
 }
 
+/* function parameter type adjustment (C11 6.7.6.3p7) */
+struct type *
+typeadjust(struct type *t)
+{
+	switch (t->kind) {
+	case TYPEARRAY:
+		t = mkpointertype(t->base, t->qual);
+		break;
+	case TYPEFUNC:
+		t = mkpointertype(t, QUALNONE);
+		break;
+	}
+
+	return t;
+}
+
 struct member *
 typemember(struct type *t, const char *name, uint64_t *offset)
 {