[src/trunk]: src/usr.bin/xlint/lint1 lint: improve initialization of arrays w...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/5e8606aa49f2
branches:  trunk
changeset: 960677:5e8606aa49f2
user:      rillig <rillig%NetBSD.org@localhost>
date:      Thu Mar 25 22:15:38 2021 +0000

description:
lint: improve initialization of arrays with designators

Initialization is still buggy but better than before.  The remaining bug
is that only the first designator determines the array size, and after
that, the array is no longer considered of unknown size.  This
contradicts C99.  More improvements to come.

diffstat:

 tests/usr.bin/xlint/lint1/msg_168.c   |   4 ++--
 tests/usr.bin/xlint/lint1/msg_168.exp |   4 ++--
 usr.bin/xlint/lint1/init.c            |  21 +++++++++++++++++++--
 3 files changed, 23 insertions(+), 6 deletions(-)

diffs (79 lines):

diff -r d3d2116db182 -r 5e8606aa49f2 tests/usr.bin/xlint/lint1/msg_168.c
--- a/tests/usr.bin/xlint/lint1/msg_168.c       Thu Mar 25 21:51:55 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_168.c       Thu Mar 25 22:15:38 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: msg_168.c,v 1.3 2021/03/07 16:40:20 rillig Exp $       */
+/*     $NetBSD: msg_168.c,v 1.4 2021/03/25 22:15:38 rillig Exp $       */
 # 3 "msg_168.c"
 
 // Test for message: array subscript cannot be > %d: %ld [168]
@@ -9,7 +9,7 @@
 void
 example(void)
 {
-       char buf[20] = {};
+       char buf[20] = {};      /* empty initializer is a GCC extension */
 
        print_string(buf + 19); /* inside the array */
 
diff -r d3d2116db182 -r 5e8606aa49f2 tests/usr.bin/xlint/lint1/msg_168.exp
--- a/tests/usr.bin/xlint/lint1/msg_168.exp     Thu Mar 25 21:51:55 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_168.exp     Thu Mar 25 22:15:38 2021 +0000
@@ -1,3 +1,3 @@
 msg_168.c(28): warning: array subscript cannot be > 19: 20 [168]
-msg_168.c(40): warning: array subscript cannot be > 2: 57 [168]
-msg_168.c(41): warning: array subscript cannot be > 2: 58 [168]
+msg_168.c(40): warning: array subscript cannot be > 51: 57 [168]
+msg_168.c(41): warning: array subscript cannot be > 51: 58 [168]
diff -r d3d2116db182 -r 5e8606aa49f2 usr.bin/xlint/lint1/init.c
--- a/usr.bin/xlint/lint1/init.c        Thu Mar 25 21:51:55 2021 +0000
+++ b/usr.bin/xlint/lint1/init.c        Thu Mar 25 22:15:38 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: init.c,v 1.131 2021/03/25 21:51:55 rillig Exp $        */
+/*     $NetBSD: init.c,v 1.132 2021/03/25 22:15:38 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: init.c,v 1.131 2021/03/25 21:51:55 rillig Exp $");
+__RCSID("$NetBSD: init.c,v 1.132 2021/03/25 22:15:38 rillig Exp $");
 #endif
 
 #include <stdlib.h>
@@ -517,9 +517,21 @@
 void
 designation_add_subscript(range_t range)
 {
+       initstack_element *istk;
+
        debug_enter();
        debug_step("subscript range is %zu ... %zu", range.lo, range.hi);
        debug_initstack();
+
+       istk = initstk_lvalue;
+       if (istk->i_array_of_unknown_size) {
+               int auto_dim = (int)(range.hi + 1);
+               if (auto_dim > istk->i_type->t_dim) {
+                       debug_step("setting the array size to %d", auto_dim);
+                       istk->i_type->t_dim = auto_dim;
+               }
+       }
+
        debug_leave();
 }
 
@@ -1280,6 +1292,11 @@
        len = strg->st_len;
 
        if (istk->i_array_of_unknown_size) {
+               /*
+                * FIXME: C99 6.7.8p22 explicitly says that only "at the end
+                * of its initializer list, the array no longer has incomplete
+                * type".
+                */
                istk->i_array_of_unknown_size = false;
                istk->i_type->t_dim = len + 1;
                setcomplete(istk->i_type, true);