[src/trunk]: src/usr.bin/xlint/lint1 lint: extend documentation about handlin...

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

details:   https://anonhg.NetBSD.org/src/rev/4ec4a0c90994
branches:  trunk
changeset: 961410:4ec4a0c90994
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Apr 18 09:53:03 2021 +0000

description:
lint: extend documentation about handling initializations

diffstat:

 usr.bin/xlint/lint1/init.c |  28 +++++++++++++++++++++++-----
 usr.bin/xlint/lint1/tree.c |   7 +++++--
 2 files changed, 28 insertions(+), 7 deletions(-)

diffs (119 lines):

diff -r 146270849b6a -r 4ec4a0c90994 usr.bin/xlint/lint1/init.c
--- a/usr.bin/xlint/lint1/init.c        Sun Apr 18 09:50:00 2021 +0000
+++ b/usr.bin/xlint/lint1/init.c        Sun Apr 18 09:53:03 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: init.c,v 1.197 2021/04/18 09:50:00 rillig Exp $        */
+/*     $NetBSD: init.c,v 1.198 2021/04/18 09:53:03 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 1.197 2021/04/18 09:50:00 rillig Exp $");
+__RCSID("$NetBSD: init.c,v 1.198 2021/04/18 09:53:03 rillig Exp $");
 #endif
 
 #include <stdlib.h>
@@ -68,7 +68,7 @@
  * array_flat or spelled out like in array_nested.  This is unusual in
  * practice and therefore only supported very basically.
  *
- * During initialization, the grammar parser calls these functions:
+ * During an initialization, the grammar parser calls these functions:
  *
  *     begin_initialization
  *             init_lbrace                     for each '{'
@@ -79,7 +79,8 @@
  *     end_initialization
  *
  * Each '{' begins a new brace level, each '}' ends the current brace level.
- * Each brace level has an associated "current object".
+ * Each brace level has an associated "current object", which is the starting
+ * point for resolving the optional designations such as '.member[3]'.
  *
  * See also:
  *     C99 6.7.8 "Initialization"
@@ -131,6 +132,12 @@
        struct brace_level *bl_enclosing;
 };
 
+/*
+ * An ongoing initialization.
+ *
+ * In most cases there is only ever a single initialization going on.  See
+ * pointer_to_compound_literal in msg_171.c for an exception.
+ */
 struct initialization {
        /* The symbol that is to be initialized. */
        sym_t           *in_sym;
@@ -210,7 +217,7 @@
 
 #define debug_indent()         do { } while (false)
 #define debug_enter()          do { } while (false)
-#define debug_step0(msg)       do { } while (false)
+#define debug_step0(fmt)       do { } while (false)
 #define debug_step1(fmt, arg0) do { } while (false)
 #define debug_step2(fmt, arg1, arg2) do { } while (false)
 #define debug_leave()          do { } while (false)
@@ -316,6 +323,10 @@
        return sym_type(member);
 }
 
+/*
+ * C99 6.7.8p22 says that the type of an array of unknown size becomes known
+ * at the end of its initializer list.
+ */
 static void
 update_type_of_array_of_unknown_size(sym_t *sym, size_t size)
 {
@@ -514,6 +525,8 @@
 /*
  * Starting at the type of the current object, resolve the type of the
  * sub-object by following each designator in the list.
+ *
+ * C99 6.7.8p18
  */
 static const type_t *
 designation_look_up(const struct designation *dn, const type_t *tp)
@@ -815,6 +828,11 @@
            in->in_brace_level->bl_enclosing == NULL)
                update_type_of_array_of_unknown_size(in->in_sym,
                    in->in_brace_level->bl_subscript);
+       /*
+        * XXX: bl_subscript is not entirely correct.
+        * It should rather be max(actually used subscript) + 1.
+        * int arr[] = { [100] = 100, [0] = 0 };
+        */
 }
 
 static void
diff -r 146270849b6a -r 4ec4a0c90994 usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Sun Apr 18 09:50:00 2021 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Sun Apr 18 09:53:03 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.277 2021/04/17 16:58:04 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.278 2021/04/18 09:53:03 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: tree.c,v 1.277 2021/04/17 16:58:04 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.278 2021/04/18 09:53:03 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -4054,6 +4054,9 @@
  * The expression can consist of PLUS, MINUS, ADDR, NAME, STRING and
  * CON. Type conversions are allowed if they do not change binary
  * representation (including width).
+ *
+ * C99 6.6 "Constant expressions"
+ * C99 6.7.8p4 restricts initializers for static storage duration
  */
 bool
 constant_addr(const tnode_t *tn, const sym_t **symp, ptrdiff_t *offsp)