/*
* type check switch statement
*/
void
typecheckswitch(Node *n)
{
int top, lno;
Type *t;
NodeList *l, *ll;
Node *ncase, *nvar;
Node *def;
lno = lineno;
typechecklist(n->ninit, Etop);
if(n->ntest != N && n->ntest->op == OTYPESW) {
// type switch
top = Etype;
typecheck(&n->ntest->right, Erv);
t = n->ntest->right->type;
if(t != T && t->etype != TINTER)
yyerror("cannot type switch on non-interface value %+N", n->ntest->right);
} else {
// value switch
top = Erv;
if(n->ntest) {
typecheck(&n->ntest, Erv);
defaultlit(&n->ntest, T);
t = n->ntest->type;
} else
t = types[TBOOL];
}
n->type = t;
def = N;
for(l=n->list; l; l=l->next) {
ncase = l->n;
setlineno(n);
if(ncase->list == nil) {
// default
if(def != N)
yyerror("multiple defaults in switch (first at %L)", def->lineno);
else
def = ncase;
} else {
for(ll=ncase->list; ll; ll=ll->next) {
setlineno(ll->n);
typecheck(&ll->n, Erv | Etype);
if(ll->n->type == T || t == T)
continue;
switch(top) {
case Erv: // expression switch
defaultlit(&ll->n, t);
if(ll->n->op == OTYPE)
yyerror("type %T is not an expression", ll->n->type);
else if(ll->n->type != T && !eqtype(ll->n->type, t))
yyerror("case %+N in %T switch", ll->n, t);
break;
case Etype: // type switch
if(ll->n->op == OLITERAL && istype(ll->n->type, TNIL))
;
else if(ll->n->op != OTYPE && ll->n->type != T)
yyerror("%#N is not a type", ll->n);
break;
}
}
}
if(top == Etype && n->type != T) {
ll = ncase->list;
nvar = ncase->nname;
if(nvar != N) {
if(ll && ll->next == nil && ll->n->type != T && !istype(ll->n->type, TNIL)) {
// single entry type switch
nvar->ntype = typenod(ll->n->type);
} else {
// multiple entry type switch or default
nvar->ntype = typenod(n->type);
}
}
}
typechecklist(ncase->nbody, Etop);
}
lineno = lno;
}
/*
* type check switch statement
*/
void
typecheckswitch(Node *n)
{
int top, lno, ptr;
char *nilonly;
Type *t, *badtype, *missing, *have;
NodeList *l, *ll;
Node *ncase, *nvar;
Node *def;
lno = lineno;
typechecklist(n->ninit, Etop);
nilonly = nil;
if(n->ntest != N && n->ntest->op == OTYPESW) {
// type switch
top = Etype;
typecheck(&n->ntest->right, Erv);
t = n->ntest->right->type;
if(t != T && t->etype != TINTER)
yyerror("cannot type switch on non-interface value %lN", n->ntest->right);
} else {
// value switch
top = Erv;
if(n->ntest) {
typecheck(&n->ntest, Erv);
defaultlit(&n->ntest, T);
t = n->ntest->type;
} else
t = types[TBOOL];
if(t) {
if(!okforeq[t->etype])
yyerror("cannot switch on %lN", n->ntest);
else if(t->etype == TARRAY && !isfixedarray(t))
nilonly = "slice";
else if(t->etype == TARRAY && isfixedarray(t) && algtype1(t, nil) == ANOEQ)
yyerror("cannot switch on %lN", n->ntest);
else if(t->etype == TSTRUCT && algtype1(t, &badtype) == ANOEQ)
yyerror("cannot switch on %lN (struct containing %T cannot be compared)", n->ntest, badtype);
else if(t->etype == TFUNC)
nilonly = "func";
else if(t->etype == TMAP)
nilonly = "map";
}
}
n->type = t;
def = N;
for(l=n->list; l; l=l->next) {
ncase = l->n;
setlineno(n);
if(ncase->list == nil) {
// default
if(def != N)
yyerror("multiple defaults in switch (first at %L)", def->lineno);
else
def = ncase;
} else {
for(ll=ncase->list; ll; ll=ll->next) {
setlineno(ll->n);
typecheck(&ll->n, Erv | Etype);
if(ll->n->type == T || t == T)
continue;
setlineno(ncase);
switch(top) {
case Erv: // expression switch
defaultlit(&ll->n, t);
if(ll->n->op == OTYPE)
yyerror("type %T is not an expression", ll->n->type);
else if(ll->n->type != T && !assignop(ll->n->type, t, nil) && !assignop(t, ll->n->type, nil)) {
if(n->ntest)
yyerror("invalid case %N in switch on %N (mismatched types %T and %T)", ll->n, n->ntest, ll->n->type, t);
else
yyerror("invalid case %N in switch (mismatched types %T and bool)", ll->n, ll->n->type);
} else if(nilonly && !isconst(ll->n, CTNIL)) {
yyerror("invalid case %N in switch (can only compare %s %N to nil)", ll->n, nilonly, n->ntest);
}
break;
case Etype: // type switch
if(ll->n->op == OLITERAL && istype(ll->n->type, TNIL)) {
;
} else if(ll->n->op != OTYPE && ll->n->type != T) { // should this be ||?
yyerror("%lN is not a type", ll->n);
// reset to original type
ll->n = n->ntest->right;
} else if(ll->n->type->etype != TINTER && t->etype == TINTER && !implements(ll->n->type, t, &missing, &have, &ptr)) {
if(have && !missing->broke && !have->broke)
yyerror("impossible type switch case: %lN cannot have dynamic type %T"
" (wrong type for %S method)\n\thave %S%hT\n\twant %S%hT",
n->ntest->right, ll->n->type, missing->sym, have->sym, have->type,
missing->sym, missing->type);
else if(!missing->broke)
yyerror("impossible type switch case: %lN cannot have dynamic type %T"
" (missing %S method)", n->ntest->right, ll->n->type, missing->sym);
}
break;
}
}
}
if(top == Etype && n->type != T) {
ll = ncase->list;
nvar = ncase->nname;
if(nvar != N) {
if(ll && ll->next == nil && ll->n->type != T && !istype(ll->n->type, TNIL)) {
// single entry type switch
nvar->ntype = typenod(ll->n->type);
} else {
// multiple entry type switch or default
nvar->ntype = typenod(n->type);
}
}
}
typechecklist(ncase->nbody, Etop);
}
lineno = lno;
}
/*
* look for
* unsafe.Sizeof
* unsafe.Offsetof
* rewrite with a constant
*/
Node*
unsafenmagic(Node *nn)
{
Node *r, *n;
Sym *s;
Type *t, *tr;
long v;
Val val;
Node *fn;
NodeList *args;
fn = nn->left;
args = nn->list;
if(safemode || fn == N || fn->op != ONAME || (s = fn->sym) == S)
goto no;
if(s->pkg != unsafepkg)
goto no;
if(args == nil) {
yyerror("missing argument for %S", s);
goto no;
}
r = args->n;
if(strcmp(s->name, "Sizeof") == 0) {
typecheck(&r, Erv);
defaultlit(&r, T);
tr = r->type;
if(tr == T)
goto bad;
dowidth(tr);
v = tr->width;
goto yes;
}
if(strcmp(s->name, "Offsetof") == 0) {
typecheck(&r, Erv);
if(r->op != ODOT && r->op != ODOTPTR)
goto bad;
typecheck(&r, Erv);
v = r->xoffset;
goto yes;
}
if(strcmp(s->name, "Alignof") == 0) {
typecheck(&r, Erv);
defaultlit(&r, T);
tr = r->type;
if(tr == T)
goto bad;
// make struct { byte; T; }
t = typ(TSTRUCT);
t->type = typ(TFIELD);
t->type->type = types[TUINT8];
t->type->down = typ(TFIELD);
t->type->down->type = tr;
// compute struct widths
dowidth(t);
// the offset of T is its required alignment
v = t->type->down->width;
goto yes;
}
no:
return N;
bad:
yyerror("invalid expression %#N", nn);
v = 0;
goto ret;
yes:
if(args->next != nil)
yyerror("extra arguments for %S", s);
ret:
// any side effects disappear; ignore init
val.ctype = CTINT;
val.u.xval = mal(sizeof(*n->val.u.xval));
mpmovecfix(val.u.xval, v);
n = nod(OLITERAL, N, N);
n->val = val;
n->type = types[TINT];
return n;
}
