[src/trunk]: src/usr.bin/xlint/lint1 lint: add error about out-of-bounds arra...

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

details:   https://anonhg.NetBSD.org/src/rev/df1b3524b6b6
branches:  trunk
changeset: 960855:df1b3524b6b6
user:      rillig <rillig%NetBSD.org@localhost>
date:      Tue Mar 30 16:07:07 2021 +0000

description:
lint: add error about out-of-bounds array subscripts

This check is not strictly necessary since any C99 compiler must
diagnose them as well, it is rather meant for demonstrating how to do
the check in lint, and for symmetry with the 'unknown member' error
message.  These provide insight into how the data structures in init.c
are meant to be accessed.

diffstat:

 tests/usr.bin/xlint/lint1/d_c99_init.c   |  12 ++++++------
 tests/usr.bin/xlint/lint1/d_c99_init.exp |   3 +++
 usr.bin/xlint/lint1/init.c               |   9 +++++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diffs (81 lines):

diff -r 60422942e72b -r df1b3524b6b6 tests/usr.bin/xlint/lint1/d_c99_init.c
--- a/tests/usr.bin/xlint/lint1/d_c99_init.c    Tue Mar 30 15:31:51 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/d_c99_init.c    Tue Mar 30 16:07:07 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: d_c99_init.c,v 1.26 2021/03/30 15:18:19 rillig Exp $   */
+/*     $NetBSD: d_c99_init.c,v 1.27 2021/03/30 16:07:07 rillig Exp $   */
 # 3 "d_c99_init.c"
 
 /*
@@ -135,7 +135,7 @@
 struct point point_with_mixed_designators = {
        .x = 3,
        4,
-       /* TODO: remove me */
+
        5,                      /* expect: too many struct/union initializers */
        .x = 3,
 };
@@ -211,15 +211,15 @@
  * structs.
  */
 struct geometry geometry = {
-       /* TODO: remove me */
+
        .pentagons[0].points[4].x = 1,
        .points[0][0][0] = { 0, 0 },
        .points[2][4][1] = {301, 302 },
-       /* TODO: expect+1: array index 3 must be between 0 and 2 */
+       /* expect+1: array subscript cannot be > 2: 3 */
        .points[3][0][0] = {3001, 3002 },
-       /* TODO: expect+1: array index 5 must be between 0 and 4 */
+       /* expect+1: array subscript cannot be > 4: 5 */
        .points[0][5][0] = {501, 502 },
-       /* TODO: expect+1: array index 2 must be between 0 and 1 */
+       /* expect+1: array subscript cannot be > 1: 2 */
        .points[0][0][2] = {21, 22 },
 };
 
diff -r 60422942e72b -r df1b3524b6b6 tests/usr.bin/xlint/lint1/d_c99_init.exp
--- a/tests/usr.bin/xlint/lint1/d_c99_init.exp  Tue Mar 30 15:31:51 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/d_c99_init.exp  Tue Mar 30 16:07:07 2021 +0000
@@ -3,6 +3,9 @@
 d_c99_init.c(80): error: too many array initializers, expected 3 [173]
 d_c99_init.c(139): error: too many struct/union initializers [172]
 d_c99_init.c(145): error: syntax error 'designator '.member' is only for struct/union' [249]
+d_c99_init.c(219): error: array subscript cannot be > 2: 3 [168]
+d_c99_init.c(221): error: array subscript cannot be > 4: 5 [168]
+d_c99_init.c(223): error: array subscript cannot be > 1: 2 [168]
 d_c99_init.c(232): error: too many struct/union initializers [172]
 d_c99_init.c(238): warning: illegal combination of integer (char) and pointer (pointer to char) [183]
 d_c99_init.c(242): warning: illegal combination of integer (char) and pointer (pointer to char) [183]
diff -r 60422942e72b -r df1b3524b6b6 usr.bin/xlint/lint1/init.c
--- a/usr.bin/xlint/lint1/init.c        Tue Mar 30 15:31:51 2021 +0000
+++ b/usr.bin/xlint/lint1/init.c        Tue Mar 30 16:07:07 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: init.c,v 1.182 2021/03/30 15:18:19 rillig Exp $        */
+/*     $NetBSD: init.c,v 1.183 2021/03/30 16:07:07 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -38,7 +38,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: init.c,v 1.182 2021/03/30 15:18:19 rillig Exp $");
+__RCSID("$NetBSD: init.c,v 1.183 2021/03/30 16:07:07 rillig Exp $");
 #endif
 
 #include <stdlib.h>
@@ -455,6 +455,11 @@
                        error(249,
                            "designator '.member' is only for struct/union");
                }
+               if (!tp->t_incomplete_array &&
+                   dr->dr_subscript >= (size_t)tp->t_dim) {
+                       /* array subscript cannot be > %d: %ld */
+                       error(168, tp->t_dim - 1, (long)dr->dr_subscript);
+               }
                return tp->t_subt;
        default:
                /* syntax error '%s' */