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struct-init: Correctly parse unnamed member initializers

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For
  union U { struct {int a,b}; int c; };
  union U u = {{ 1, 2, }};
The unnamed first member of union U needs to actually exist in the
structure so initializer parsing isn't confused about the double braces.
That means also the a and b members must be part of _that_, not of
union U directly.  Which in turn means we need to do a bit more work
for field lookup.

See the testcase extension for more things that need to work.
This commit is contained in:
Michael Matz 2016-08-01 22:11:49 +02:00
parent 21da73c383
commit 9e86ebee94
3 changed files with 78 additions and 21 deletions
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72
tccgen.c
View File

@ -3181,6 +3181,22 @@ static void parse_attribute(AttributeDef *ad)
}
}
static Sym * find_field (CType *type, int v)
{
Sym *s = type->ref;
v |= SYM_FIELD;
while ((s = s->next) != NULL) {
if ((s->v & SYM_FIELD) && (s->v & ~SYM_FIELD) >= SYM_FIRST_ANOM) {
Sym *ret = find_field (&s->type, v);
if (ret)
return ret;
}
if (s->v == v)
break;
}
return s;
}
/* enum/struct/union declaration. u is either VT_ENUM or VT_STRUCT */
static void struct_decl(CType *type, AttributeDef *ad, int u)
{
@ -3404,13 +3420,40 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
#endif
}
if (v == 0 && (type1.t & VT_BTYPE) == VT_STRUCT) {
/* An anonymous struct/union. Adjust member offsets
to reflect the real offset of our containing struct.
Also set the offset of this anon member inside
the outer struct to be zero. Via this it
works when accessing the field offset directly
(from base object), as well as when recursing
members in initializer handling. */
int v2 = btype.ref->v;
if (!(v2 & SYM_FIELD) &&
(v2 & ~SYM_STRUCT) < SYM_FIRST_ANOM) {
Sym **pps;
/* This happens only with MS extensions. The
anon member has a named struct type, so it
potentially is shared with other references.
We need to unshare members so we can modify
them. */
ass = type1.ref;
type1.ref = sym_push(anon_sym++ | SYM_FIELD,
&type1.ref->type, 0,
type1.ref->c);
pps = &type1.ref->next;
while ((ass = ass->next) != NULL) {
*pps = sym_push(ass->v, &ass->type, 0, ass->c);
pps = &((*pps)->next);
}
*pps = NULL;
}
ass = type1.ref;
while ((ass = ass->next) != NULL) {
ss = sym_push(ass->v, &ass->type, 0, offset + ass->c);
*ps = ss;
ps = &ss->next;
}
} else if (v) {
while ((ass = ass->next) != NULL)
ass->c += offset;
offset = 0;
v = anon_sym++;
}
if (v) {
ss = sym_push(v | SYM_FIELD, &type1, 0, offset);
*ps = ss;
ps = &ss->next;
@ -4536,13 +4579,7 @@ ST_FUNC void unary(void)
next();
if (tok == TOK_CINT || tok == TOK_CUINT)
expect("field name");
s = vtop->type.ref;
/* find field */
tok |= SYM_FIELD;
while ((s = s->next) != NULL) {
if (s->v == tok)
break;
}
s = find_field(&vtop->type, tok);
if (!s)
tcc_error("field not found: %s", get_tok_str(tok & ~SYM_FIELD, &tokc));
/* add field offset to pointer */
@ -5729,14 +5766,7 @@ static void decl_designator(CType *type, Section *sec, unsigned long c,
struct_field:
if ((type->t & VT_BTYPE) != VT_STRUCT)
expect("struct/union type");
s = type->ref;
l |= SYM_FIELD;
f = s->next;
while (f) {
if (f->v == l)
break;
f = f->next;
}
f = find_field(type, l);
if (!f)
expect("field");
if (!notfirst)

23
tests/tests2/86-struct-init.c
View File

@ -77,6 +77,25 @@ struct SU {
};
struct SU gsu = {5,6};
/* Unnamed struct/union members aren't ISO C, but it's a widely accepted
extension. See below for further extensions to that under -fms-extension.*/
union UV {
struct {u8 a,b;};
struct S s;
};
union UV guv = {{6,5}};
union UV guv2 = {{.b = 7, .a = 8}};
union UV guv3 = {.b = 8, .a = 7};
/* Under -fms-extensions also the following is valid:
union UV2 {
struct Anon {u8 a,b;}; // unnamed member, but tagged struct, ...
struct S s;
};
struct Anon gan = { 10, 11 }; // ... which makes it available here.
union UV2 guv4 = {{4,3}}; // and the other inits from above as well
*/
#include <stdio.h>
void print_ (const char *name, const u8 *p, long size)
{
@ -144,6 +163,10 @@ int main()
print(sinit16);
print(gw);
print(gsu);
print(guv);
print(guv.b);
print(guv2);
print(guv3);
foo(&gw);
//printf("q: %s\n", q);
return 0;

4
tests/tests2/86-struct-init.expect
View File

@ -13,6 +13,10 @@ gv3: 7 8 9 a 68 6f 68 6f 0 0 0 0 0 0 0 0 0 0 0 0 31 32
sinit16: 1 0 0 0 2 0 0 0
gw: 1 2 3 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
gsu: 5 6
guv: 6 5 0 0
guv.b: 5
guv2: 8 7 0 0
guv3: 7 8 0 0
ls: 1 2 3 4
ls2: 1 2 3 4
lt: 68 65 6c 6c 6f 0 0 0 0 0 0 0 0 0 0 0 2a