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-rw-r--r--src/c.c42
-rw-r--r--src/c_type.c20
-rw-r--r--src/c_type.h8
-rw-r--r--test/20-empty.c28
4 files changed, 67 insertions, 31 deletions
diff --git a/src/c.c b/src/c.c
index 5fadedc..c1993e2 100644
--- a/src/c.c
+++ b/src/c.c
@@ -345,7 +345,6 @@ finddecl(CComp *cm, internstr name)
static Type
gettagged(CComp *cm, Span *span, enum typetag tt, internstr name, bool dodef)
{
- TypeData td = {0};
assert(name);
for (Env *e = cm->env; e; e = e->up) {
for (Tagged *l = NULL; envitertagged(&l, e);) {
@@ -361,14 +360,12 @@ gettagged(CComp *cm, Span *span, enum typetag tt, internstr name, bool dodef)
warn(span, "forward-declared enum is an extension");
}
Break2:
- td.t = tt;
- return envaddtagged(cm->env, mktagtype(name, &td), span)->ty;
+ return envaddtagged(cm->env, mktagtype(name, &(TypeData){tt, TFUNKNOWN}), span)->ty;
}
static Type
deftagged(CComp *cm, Span *span, enum typetag tt, internstr name, Type ty)
{
- TypeData td = {0};
assert(name);
for (Tagged *l = NULL; envitertagged(&l, cm->env);) {
if (name == tagtypetags[typedata[l->ty.dat].id]) {
@@ -376,8 +373,7 @@ deftagged(CComp *cm, Span *span, enum typetag tt, internstr name, Type ty)
return l->ty;
}
}
- td.t = tt;
- return envaddtagged(cm->env, ty.t ? ty : mktagtype(name, &td), span)->ty;
+ return envaddtagged(cm->env, ty.t ? ty : mktagtype(name, &(TypeData){tt, TFUNKNOWN}), span)->ty;
}
/*********************/
@@ -398,8 +394,7 @@ argpromote(Type t)
{
if (isint(t)) t.t = intpromote(t.t);
else if (t.t == TYFLOAT) t.t = TYDOUBLE;
- else if (t.t == TYARRAY) return mkptrtype(typechild(t), t.flag & TFCHLDQUAL);
- else if (t.t == TYFUNC) return mkptrtype(t, 0);
+ else if (t.t == TYARRAY || t.t == TYFUNC) t = typedecay(t);
return t;
}
@@ -1319,7 +1314,7 @@ static uint
nmemb(Type ty)
{
switch (ty.t) {
- case TYARRAY: return typearrlen(ty) ? typearrlen(ty) : -1u;
+ case TYARRAY: return isincomplete(ty) ? -1u : typearrlen(ty);
case TYUNION: case TYSTRUCT: return typedata[ty.dat].nmemb;
default: return 1;
}
@@ -1613,7 +1608,7 @@ ininext(InitParser *ip, CComp *cm)
Retry:
targ = membertype(&off, &bitsiz, &bitoff, ip->sub->ty, ip->sub->idx);
- if (isagg(ip->sub->ty) && targ.t == TYARRAY && !typearrlen(targ)) {
+ if (isagg(ip->sub->ty) && targ.t == TYARRAY && isincomplete(targ)) {
error(&ex.span, "cannot initialize flexible array member");
++ip->sub->idx;
return;
@@ -1876,8 +1871,8 @@ initializer(CComp *cm, Type *ty, enum evalmode ev, bool globl,
if (isincomplete(*ty)) {
uint len = ip->arrlen > ip->cur->idx ? ip->arrlen : ip->cur->idx;
- if (len == 0)
- error(&span, "array cannot have zero length");
+ if (len == 0 && ccopt.pedant)
+ warn(&span, "zero size array is an extension");
*ty = mkarrtype(typechild(*ty), ty->flag & TFCHLDQUAL, len);
}
Dynfix:
@@ -1906,8 +1901,8 @@ initializer(CComp *cm, Type *ty, enum evalmode ev, bool globl,
uint siz;
if (isincomplete(*ty)) {
uint len = ip->arrlen > ip->cur->idx ? ip->arrlen : ip->cur->idx;
- if (!len)
- error(&span, "initializer creates a zero-sized array");
+ if (!len && ccopt.pedant)
+ warn(&span, "initializer creates a zero size array");
*ty = mkarrtype(typechild(*ty), ty->flag & TFCHLDQUAL, len);
}
@@ -2011,7 +2006,7 @@ buildagg(CComp *cm, enum typetag tt, internstr name, int id)
td.flexi = 0;
error(&flexspan, "flexible array member is not at end of struct");
}
- if (!isunion && decl.ty.t == TYARRAY && !typearrlen(decl.ty)) {
+ if (!isunion && decl.ty.t == TYARRAY && typearrlen(decl.ty) == 0) {
td.flexi = 1;
flexspan = decl.span;
} else if (isincomplete(decl.ty)) {
@@ -2098,14 +2093,16 @@ buildagg(CComp *cm, enum typetag tt, internstr name, int id)
} while (st.more);
}
if (td.flexi && fld.n == 1)
- error(&flexspan, "flexible array member in otherwise empty aggregate");
+ warn(&flexspan, "flexible array member in otherwise empty aggregate");
if (td.flexi && ccopt.cstd < STDC99 && ccopt.pedant)
warn(&flexspan, "flexible array member in %M is an extension");
if (fld.n == 0) {
NamedField dummy = { intern(""), { mktype(TYCHAR), 0 }};
- error(&tk.span, "%s cannot have zero members", tag);
+ if (ccopt.pedant)
+ warn(&tk.span, "%s with zero members is an extension", tag);
vpush(&fld, dummy);
- td.siz = td.align = 1;
+ td.siz = 0;
+ td.align = 1;
}
td.siz = alignup(td.siz, td.align);
td.fld = fld.p;
@@ -2768,7 +2765,7 @@ declarator(DeclState *st, CComp *cm, Span span0) {
else if (decl.ty.t == TYFUNC)
error(&l->span, "array has element has function type '%ty'", decl.ty);
if (l->count.t == EARRAYUNSIZED) /* unsized '[]' */
- decl.ty = mkarrtype(decl.ty, decl.qual, 0);
+ decl.ty = mkunszarrtype(decl.ty, decl.qual);
else {
uint n = 0;
Expr *ex = &l->count;
@@ -2781,10 +2778,8 @@ declarator(DeclState *st, CComp *cm, Span span0) {
} else if (ex->u > (1ull << (8*sizeof n)) - 1) {
error(&ex->span, "array too long (%ul)", ex->u);
} else if (ex->u == 0) {
- /* when struct field, silently accept zero-length as synonym of '[]' for flexible array member */
- if (l->prev != &list || st->kind != DFIELD) {
- warn(&ex->span, "array cannot have zero length");
- }
+ if (ccopt.pedant)
+ warn(&ex->span, "zero size array is an extension");
} else {
n = ex->u;
}
@@ -4735,6 +4730,7 @@ docomp(CComp *cm)
cm->env = &toplevel;
}
if (!cvalistty.t) {
+ /* XXX hardcoded va_list impl */
TypeData td = {
.t = TYSTRUCT, .siz = targ_valistsize, .align = targ_primalign[TYPTR], .nmemb = 1,
.fld = &(NamedField){intern("-"), {mkarrtype(mktype(TYPTR), 0, 3)}}
diff --git a/src/c_type.c b/src/c_type.c
index 5853eb8..ef4770d 100644
--- a/src/c_type.c
+++ b/src/c_type.c
@@ -105,11 +105,13 @@ interntd(const TypeData *td)
*slot = *td;
switch (slot->t) {
case TYENUM:
+ assert(!(td->flag & TFUNKNOWN) || (!td->var && !td->siz));
if (slot->var)
slot->var = alloccopy(&datarena, td->var, nmemb * sizeof *slot->var, 0);
break;
case TYSTRUCT:
case TYUNION:
+ assert(!(td->flag & TFUNKNOWN) || (td->nmemb == 0 && !td->siz));
if (slot->fld)
slot->fld = alloccopy(&datarena, td->fld, nmemb * sizeof *slot->fld, 0);
break;
@@ -132,12 +134,11 @@ isincomplete(Type t)
{
switch (t.t) {
case TYVOID: return 1;
- case TYARRAY: return !typearrlen(t);
+ case TYARRAY: return t.flag & TFUNKNOWN;
+ case TYENUM:
case TYSTRUCT:
case TYUNION:
- return typedata[t.dat].nmemb == 0;
- case TYENUM:
- return !typedata[t.dat].backing;
+ return typedata[t.dat].flag & TFUNKNOWN;
}
return 0;
}
@@ -197,6 +198,15 @@ mkarrtype(Type t, int qual, uint n)
}
Type
+mkunszarrtype(Type t, int qual)
+{
+ if (isprim(t))
+ return mktype(TYARRAY, .flag = TFCHLDPRIM | (qual & TFCHLDQUAL) | TFUNKNOWN, .child = t.t);
+ return mktype(TYARRAY, .flag = TFUNKNOWN | (qual & TFCHLDQUAL),
+ .dat = interntd(&(TypeData) { TYARRAY, TFUNKNOWN, .child = t }));
+}
+
+Type
mkfntype(Type ret, uint n, const Type *par, bool kandr, bool variadic)
{
TypeData td = { TYFUNC, .ret = ret, .nmemb = n, .param = par };
@@ -214,7 +224,7 @@ completetype(internstr name, int id, TypeData *td)
assert(tagtypetags[id] == name && "bad redefn");
else
tagtypetags[id] = name;
- return mktype(td->t, .dat = interntd(td));
+ return mktype(td->t, .flag = td->flag, .dat = interntd(td));
}
Type
diff --git a/src/c_type.h b/src/c_type.h
index 6f9a265..6ef1bc3 100644
--- a/src/c_type.h
+++ b/src/c_type.h
@@ -25,12 +25,12 @@ enum typeflagmask {
TFCHLDQUAL = 3,
TFCHLDPRIM = 1<<2,
TFCHLDISDAT = 1<<3,
+ TFUNKNOWN = 1<<4, /* array of unknown size, tagged type of unknown content */
};
-
typedef union Type {
struct {
uchar t; /* type tag */
- uchar flag;
+ uchar flag; /* enum typeflagmask */
union {
struct {
uchar child; /* prim type tag */
@@ -85,6 +85,7 @@ typedef struct {
typedef struct TypeData {
uchar t;
+ uchar flag;
ushort id;
union {
Type child;
@@ -127,6 +128,7 @@ uint typesize(Type);
uint typealign(Type);
Type mkptrtype(Type, int qual);
Type mkarrtype(Type t, int qual, uint n);
+Type mkunszarrtype(Type t, int qual);
Type mkfntype(Type ret, uint n, const Type *, bool kandr, bool variadic);
Type mktagtype(internstr name, TypeData *td);
bool getfield(FieldData *res, Type, internstr);
@@ -141,7 +143,7 @@ typechild(Type t)
if (t.t == TYENUM) return mktype(typedata[t.dat].backing);
if (t.flag & TFCHLDPRIM) return mktype(t.child);
if (t.flag & TFCHLDISDAT) {
- Type chld = mktype(typedata[t.dat].t, .dat = t.dat);
+ Type chld = mktype(typedata[t.dat].t, .flag = typedata[t.dat].flag, .dat = t.dat);
return chld;
}
return typedata[t.dat].child;
diff --git a/test/20-empty.c b/test/20-empty.c
new file mode 100644
index 0000000..2926185
--- /dev/null
+++ b/test/20-empty.c
@@ -0,0 +1,28 @@
+/* EXPECT:
+sizeof (struct empty) === 0
+sizeof bleh[1] === 0
+sizeof (struct flx0) == sizeof (int) === 1
+sizeof (a) === 0
+sizeof (aa) === 0
+*/
+
+void f(){}
+
+struct empty {};
+extern struct empty bleh[10];
+struct flx0 { int t; int m[0]; };
+
+int main() {
+ int a[] = {};
+ int aa[][0] = {};
+ struct empty empty = {};
+
+ extern int printf(const char *, ...);
+#define P(x) printf(#x" === %d\n", (int)x)
+ P(sizeof (struct empty));
+ P(sizeof bleh[1]);
+ P(sizeof (struct flx0) == sizeof (int));
+ P(sizeof (a));
+ P(sizeof (aa));
+}
+
generated by cgit v1.2.3 (git 2.39.1) at 2026-05-01 18:37:23 +0000