lint: add comments about things left to do, from code review
No functional change.
This commit is contained in:
rillig
parent
e11a27e948
commit
6d41f06e4c
@ -1,4 +1,4 @@
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/* $NetBSD: init.c,v 1.118 2021/03/25 01:42:53 rillig Exp $ */
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/* $NetBSD: init.c,v 1.119 2021/03/25 13:10:19 rillig Exp $ */
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/*
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* Copyright (c) 1994, 1995 Jochen Pohl
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@ -37,7 +37,7 @@
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#include <sys/cdefs.h>
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#if defined(__RCSID) && !defined(lint)
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__RCSID("$NetBSD: init.c,v 1.118 2021/03/25 01:42:53 rillig Exp $");
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__RCSID("$NetBSD: init.c,v 1.119 2021/03/25 13:10:19 rillig Exp $");
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#endif
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#include <stdlib.h>
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@ -59,21 +59,30 @@ __RCSID("$NetBSD: init.c,v 1.118 2021/03/25 01:42:53 rillig Exp $");
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* int array_nested[2][2] = { { 11, 12 }, { 21, 22 } };
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*
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* struct { int x, y; } point = { 3, 4 };
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* struct { int x, y; } point = { .y = 3, .x = 4 };
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* struct { int x, y; } point = { .y = 4, .x = 3 };
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*
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* Any scalar expression in the initializer may be surrounded by an extra pair
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* of braces, like in the example 'number_with_braces' (C99 6.7.8p11). For
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* multi-dimensional arrays, the inner braces may be omitted like in
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* Any scalar expression in the initializer may be surrounded by arbitrarily
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* many extra pairs of braces, like in the example 'number_with_braces' (C99
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* 6.7.8p11).
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*
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* For multi-dimensional arrays, the inner braces may be omitted like in
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* array_flat or spelled out like in array_nested.
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*
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* For the initializer, the grammar parser calls these functions:
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*
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* init_lbrace for each '{'
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* init_using_expr for each value
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* init_rbrace for each '}'
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* begin_initialization
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* init_lbrace for each '{'
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* designator_push_name for each '.member' before '='
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* designator_push_subscript for each '[123]' before '='
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* init_using_expr for each expression
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* init_rbrace for each '}'
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* end_initialization
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*
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* The state of the current initialization is stored in initstk, a stack of
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* initstack_element, one element per type aggregate level.
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* XXX: Or is that "one element per brace level"? C99 mandates in 6.7.8p17
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* that "each brace-enclosed initializer list has an associated current
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* object".
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*
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* Most of the time, the topmost level of initstk contains a scalar type, and
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* its remaining count toggles between 1 and 0.
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@ -87,16 +96,11 @@ __RCSID("$NetBSD: init.c,v 1.118 2021/03/25 01:42:53 rillig Exp $");
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/*
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* Type of stack which is used for initialization of aggregate types.
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*
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* XXX: Since C99, a stack is an inappropriate data structure for modelling
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* an initialization, since the designators don't have to be listed in a
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* particular order and can designate parts of sub-objects. The member names
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* XXX: Since C99, the initializers can be listed in arbitrary order by using
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* designators to specify the sub-object to be initialized. The member names
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* of non-leaf structs may thus appear repeatedly, as demonstrated in
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* d_init_pop_member.c.
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*
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* XXX: During initialization, there may be members of the top-level struct
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* that are partially initialized. The simple i_remaining cannot model this
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* appropriately.
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*
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* See C99 6.7.8, which spans 6 pages full of tricky details and carefully
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* selected examples.
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*/
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@ -107,8 +111,11 @@ typedef struct initstack_element {
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*
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* On the outermost element, this is always NULL since the outermost
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* initializer-expression may be enclosed in an optional pair of
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* braces. This optional pair of braces is handled by the combination
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* of i_type and i_subt.
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* braces, as of the current implementation.
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*
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* FIXME: This approach is wrong. It's not that the outermost
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* initializer may be enclosed in additional braces, it's every scalar
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* that may be enclosed in additional braces, as of C99 6.7.8p11.
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*
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* Everywhere else it is nonnull.
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*/
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@ -131,28 +138,48 @@ typedef struct initstack_element {
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*
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* During initialization, only the top 2 elements of the stack are
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* looked at.
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*
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* XXX: Having i_subt here is the wrong approach, it should not be
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* necessary at all; see i_type.
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*/
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type_t *i_subt;
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/*
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* This level of the initializer requires a '}' to be completed.
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* Whether this level of the initializer requires a '}' to be
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* completed.
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*
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* Multidimensional arrays do not need a closing brace to complete
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* an inner array; for example, { 1, 2, 3, 4 } is a valid initializer
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* for int arr[2][2].
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* for 'int arr[2][2]'.
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*
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* TODO: Do structs containing structs need a closing brace?
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* TODO: Do arrays of structs need a closing brace after each struct?
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*
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* XXX: Double-check whether this is the correct approach at all; see
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* i_type.
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*/
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bool i_brace: 1;
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/* Whether i_type is an array of unknown size. */
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bool i_array_of_unknown_size: 1;
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/*
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* XXX: This feels wrong. Whether or not there has been a named
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* initializer (called 'designation' since C99) should not matter at
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* all. Even after an initializer with designation, counting of the
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* remaining elements continues, see C99 6.7.8p17.
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*/
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bool i_seen_named_member: 1;
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/*
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* For structs, the next member to be initialized by an initializer
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* without an optional designator.
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*
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* FIXME: The name is wrong. C99 defines the "current object" as
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* being the subobject being initialized, while this is rather the
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* next member. This only makes sense for structs anyway and should
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* be amended by i_next_subscript for arrays. See C99 6.7.8p17 and
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* footnote 128 for unions.
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*/
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sym_t *i_current_object;
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@ -170,14 +197,23 @@ typedef struct initstack_element {
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* XXX: for structs?
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* XXX: for unions?
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* XXX: for arrays?
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*
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* XXX: Having the count of remaining objects should not be necessary.
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* It is probably clearer to use i_next_member and i_next_subscript
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* (as suggested in i_current_object) for this purpose.
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*/
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int i_remaining;
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/*
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* The initialization state of the enclosing data structure
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* (struct, union, array).
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*
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* XXX: Or for a scalar, for the top-level element, or for expressions
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* in redundant braces such as '{{{{ 0 }}}}' (not yet implemented as
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* of 2021-03-25).
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*/
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struct initstack_element *i_enclosing;
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} initstack_element;
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/*
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@ -223,8 +259,12 @@ struct initialization {
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static struct initialization *init;
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/* XXX: unnecessary prototype since it is not recursive */
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static bool init_array_using_string(tnode_t *);
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/* TODO: replace the following functions with current_init */
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bool *
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current_initerr(void)
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{
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@ -253,10 +293,10 @@ current_initstk(void)
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return &init->initstk;
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}
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#define initerr (*current_initerr())
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#define initsym (*current_initsym())
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#define initstk (*current_initstk())
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#define namedmem (*current_namedmem())
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#define initerr (*current_initerr())
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#define initsym (*current_initsym())
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#define initstk (*current_initstk())
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#define namedmem (*current_namedmem())
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#ifndef DEBUG
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@ -330,9 +370,18 @@ debug_named_member(void)
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debug_printf("\n");
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}
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/*
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* TODO: try whether a single-line output is more readable
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*
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* TODO: only log the top of the stack after each modifying operation
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*
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* TODO: wrap all write accesses to initstack_element in setter functions
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*/
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static void
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debug_initstack_element(const initstack_element *elem)
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{
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/* TODO: use debug_ind++ instead of the leading spaces here */
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if (elem->i_type != NULL)
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debug_step(" i_type = %s", type_name(elem->i_type));
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if (elem->i_subt != NULL)
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@ -354,6 +403,9 @@ debug_initstack_element(const initstack_element *elem)
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debug_step(" i_remaining = %d", elem->i_remaining);
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}
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/*
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* TODO: only call debug_initstack after each push/pop.
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*/
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static void
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debug_initstack(void)
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{
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@ -410,7 +462,7 @@ designator_push_name(sbuf_t *sb)
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/*
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* XXX: Why is this a circular list?
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* XXX: Why is this a doubly-linked list?
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* A simple stack should suffice.
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* A simple queue should suffice.
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*/
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nam->n_prev = nam->n_next = nam;
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namedmem = nam;
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@ -425,11 +477,21 @@ designator_push_name(sbuf_t *sb)
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}
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/*
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* A struct member that has array type is initialized using a designator.
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* A sub-object of an array is initialized using a designator. This does not
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* have to be an array element directly, it can also be used to initialize
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* only a sub-object of the array element.
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*
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* C99 example: struct { int member[4]; } var = { [2] = 12345 };
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*
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* GNU example: struct { int member[4]; } var = { [1 ... 3] = 12345 };
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*
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* TODO: test the following initialization with an outer and an inner type:
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*
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* .deeply[0].nested = {
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* .deeply[1].nested = {
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* 12345,
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* },
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* }
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*/
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void
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designator_push_subscript(range_t range)
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@ -440,6 +502,7 @@ designator_push_subscript(range_t range)
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debug_leave();
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}
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/* TODO: add support for array subscripts, not only named members */
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static void
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designator_shift_name(void)
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{
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@ -460,6 +523,8 @@ designator_shift_name(void)
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/*
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* Initialize the initialization stack by putting an entry for the object
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* which is to be initialized on it.
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*
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* TODO: merge into begin_initialization
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*/
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void
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initstack_init(void)
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@ -469,11 +534,14 @@ initstack_init(void)
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if (initerr)
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return;
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/* TODO: merge into end_initialization */
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/* free memory used in last initialization */
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while ((istk = initstk) != NULL) {
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initstk = istk->i_enclosing;
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free(istk);
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}
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/* TODO: merge into init_using_expr */
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while (namedmem != NULL)
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designator_shift_name();
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@ -485,6 +553,7 @@ initstack_init(void)
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*/
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if (initsym->s_type->t_tspec == ARRAY && is_incomplete(initsym->s_type))
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initsym->s_type = duptyp(initsym->s_type);
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/* TODO: does 'duptyp' create a memory leak? */
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istk = initstk = xcalloc(1, sizeof (initstack_element));
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istk->i_subt = initsym->s_type;
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@ -494,12 +563,17 @@ initstack_init(void)
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debug_leave();
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}
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/* TODO: document me */
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static void
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initstack_pop_item_named_member(void)
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{
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initstack_element *istk = initstk;
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sym_t *m;
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/*
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* TODO: fix wording of the debug message; this doesn't seem to be
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* related to initializing the named member.
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*/
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debug_step("initializing named member '%s'", namedmem->n_name);
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if (istk->i_type->t_tspec != STRUCT &&
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@ -534,6 +608,7 @@ initstack_pop_item_named_member(void)
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istk->i_seen_named_member = true;
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}
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/* TODO: think of a better name than 'pop' */
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static void
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initstack_pop_item_unnamed(void)
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{
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@ -558,6 +633,7 @@ initstack_pop_item_unnamed(void)
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}
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}
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/* TODO: think of a better name than 'pop' */
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static void
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initstack_pop_item(void)
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{
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@ -600,6 +676,7 @@ initstack_pop_brace(void)
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debug_initstack();
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do {
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brace = initstk->i_brace;
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/* TODO: improve wording of the debug message */
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debug_step("loop brace=%d", brace);
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initstack_pop_item();
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} while (!brace);
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@ -611,6 +688,7 @@ initstack_pop_brace(void)
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* Take all entries which cannot be used for further initializers from the
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* stack, but do this only if they do not require a closing brace.
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*/
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/* TODO: think of a better name than 'pop' */
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static void
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initstack_pop_nobrace(void)
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{
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@ -647,6 +725,8 @@ extend_if_array_of_unknown_size(void)
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debug_step("extended type is '%s'", type_name(istk->i_type));
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}
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/* TODO: document me */
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/* TODO: think of a better name than 'push' */
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static void
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initstack_push_array(void)
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{
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@ -674,9 +754,15 @@ initstack_push_array(void)
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type_name(istk->i_type), istk->i_remaining);
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}
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/* TODO: document me */
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/* TODO: think of a better name than 'push' */
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static bool
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initstack_push_struct_or_union(void)
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{
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/*
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* TODO: remove unnecessary 'const' for variables in functions that
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* fit on a single screen. Keep it for larger functions.
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*/
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initstack_element *const istk = initstk;
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int cnt;
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sym_t *m;
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@ -698,7 +784,16 @@ initstack_push_struct_or_union(void)
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m != NULL; m = m->s_next) {
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if (m->s_bitfield && m->s_name == unnamed)
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continue;
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/*
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* TODO: split into separate functions:
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*
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* look_up_array_next
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* look_up_array_designator
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* look_up_struct_next
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* look_up_struct_designator
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*/
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if (namedmem != NULL) {
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/* XXX: this log entry looks unnecessarily verbose */
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debug_step("have member '%s', want member '%s'",
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m->s_name, namedmem->n_name);
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if (strcmp(m->s_name, namedmem->n_name) == 0) {
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@ -739,6 +834,8 @@ initstack_push_struct_or_union(void)
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return false;
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}
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/* TODO: document me */
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/* TODO: think of a better name than 'push' */
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static void
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initstack_push(void)
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{
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@ -786,6 +883,7 @@ again:
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if (namedmem != NULL) {
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debug_step("pop scalar");
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pop:
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/* TODO: extract this into end_initializer_level */
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inxt = initstk->i_enclosing;
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free(istk);
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initstk = inxt;
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@ -807,6 +905,9 @@ check_too_many_initializers(void)
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const initstack_element *istk = initstk;
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if (istk->i_remaining > 0)
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return;
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/*
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* FIXME: even with named members, there can be too many initializers
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*/
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if (istk->i_array_of_unknown_size || istk->i_seen_named_member)
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return;
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@ -857,6 +958,7 @@ initstack_next_brace(void)
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debug_leave();
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}
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/* TODO: document me, or think of a better name */
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static void
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initstack_next_nobrace(tnode_t *tn)
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{
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@ -892,6 +994,7 @@ initstack_next_nobrace(tnode_t *tn)
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debug_leave();
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}
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/* TODO: document me */
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void
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init_lbrace(void)
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{
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@ -951,6 +1054,7 @@ check_bit_field_init(const tnode_t *ln, tspec_t lt, tspec_t rt)
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static void
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check_non_constant_initializer(const tnode_t *tn, scl_t sclass)
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{
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/* TODO: rename CON to CONSTANT to avoid ambiguity with CONVERT */
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if (tn == NULL || tn->tn_op == CON)
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return;
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@ -969,8 +1073,8 @@ check_non_constant_initializer(const tnode_t *tn, scl_t sclass)
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}
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/*
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* Local initialization of non-array-types with only one expression without
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* braces is done by ASSIGN.
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* Initialize a non-array object with automatic storage duration and only a
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* single initializer expression without braces by delegating to ASSIGN.
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*/
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static bool
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init_using_assign(tnode_t *rn)
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@ -983,11 +1087,14 @@ init_using_assign(tnode_t *rn)
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return false;
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debug_step("handing over to ASSIGN");
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ln = new_name_node(initsym, 0);
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ln->tn_type = tduptyp(ln->tn_type);
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ln->tn_type->t_const = false;
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tn = build(ASSIGN, ln, rn);
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expr(tn, false, false, false, false);
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/* XXX: why not clean up the initstack here already? */
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return true;
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}
|
||||
@ -1018,7 +1125,7 @@ check_init_expr(tnode_t *tn, scl_t sclass)
|
||||
return;
|
||||
|
||||
/*
|
||||
* Store the tree memory. This is necessary because otherwise
|
||||
* Preserve the tree memory. This is necessary because otherwise
|
||||
* expr() would free it.
|
||||
*/
|
||||
tmem = tsave();
|
||||
@ -1110,9 +1217,14 @@ init_array_using_string(tnode_t *tn)
|
||||
return false;
|
||||
}
|
||||
/* XXX: duplicate code, see below */
|
||||
|
||||
/* Put the array at top of stack */
|
||||
initstack_push();
|
||||
istk = initstk;
|
||||
|
||||
|
||||
/* TODO: what if both i_type and i_subt are ARRAY? */
|
||||
|
||||
} else if (istk->i_type != NULL && istk->i_type->t_tspec == ARRAY) {
|
||||
debug_step("type array");
|
||||
t = istk->i_type->t_subt->t_tspec;
|
||||
@ -1123,6 +1235,11 @@ init_array_using_string(tnode_t *tn)
|
||||
return false;
|
||||
}
|
||||
/* XXX: duplicate code, see above */
|
||||
|
||||
/*
|
||||
* TODO: is this really not needed in the branch above this
|
||||
* one?
|
||||
*/
|
||||
/*
|
||||
* If the array is already partly initialized, we are
|
||||
* wrong here.
|
||||
@ -1144,10 +1261,21 @@ init_array_using_string(tnode_t *tn)
|
||||
istk->i_type->t_dim = len + 1;
|
||||
setcomplete(istk->i_type, true);
|
||||
} else {
|
||||
/*
|
||||
* TODO: check for buffer overflow in the object to be
|
||||
* initialized
|
||||
*/
|
||||
/* XXX: double-check for off-by-one error */
|
||||
if (istk->i_type->t_dim < len) {
|
||||
/* non-null byte ignored in string initializer */
|
||||
warning(187);
|
||||
}
|
||||
|
||||
/*
|
||||
* TODO: C99 6.7.8p14 allows a string literal to be enclosed
|
||||
* in optional redundant braces, just like scalars. Add tests
|
||||
* for this.
|
||||
*/
|
||||
}
|
||||
|
||||
/* In every case the array is initialized completely. */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user