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cmd/gc: fix comparison of struct with _ field

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Fixes #2989.

R=ken2
CC=golang-dev
https://golang.org/cl/5674091
This commit is contained in:
Russ Cox 2012-02-17 14:45:29 -05:00
parent ce020ffacd
commit c4c92ebeb6
4 changed files with 45 additions and 5 deletions
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1
src/cmd/gc/go.h
View File

@ -1172,6 +1172,7 @@ int implements(Type *t, Type *iface, Type **missing, Type **have, int *ptr);
void importdot(Pkg *opkg, Node *pack);
int is64(Type *t);
int isblank(Node *n);
int isblanksym(Sym *s);
int isfixedarray(Type *t);
int isideal(Type *t);
int isinter(Type *t);

25
src/cmd/gc/subr.c
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@ -571,6 +571,8 @@ algtype1(Type *t, Type **bad)
}
ret = AMEM;
for(t1=t->type; t1!=T; t1=t1->down) {
if(isblanksym(t1->sym))
continue;
a = algtype1(t1->type, bad);
if(a == ANOEQ)
return ANOEQ; // not comparable
@ -887,12 +889,20 @@ isslice(Type *t)
int
isblank(Node *n)
{
if(n == N)
return 0;
return isblanksym(n->sym);
}
int
isblanksym(Sym *s)
{
char *p;
if(n == N || n->sym == S)
if(s == S)
return 0;
p = n->sym->name;
p = s->name;
if(p == nil)
return 0;
return p[0] == '_' && p[1] == '\0';
@ -2652,12 +2662,14 @@ genhash(Sym *sym, Type *t)
// and calling specific hash functions for the others.
first = T;
for(t1=t->type;; t1=t1->down) {
if(t1 != T && algtype1(t1->type, nil) == AMEM) {
if(t1 != T && (isblanksym(t1->sym) || algtype1(t1->type, nil) == AMEM)) {
if(first == T)
first = t1;
continue;
}
// Run memhash for fields up to this one.
while(first != T && isblanksym(first->sym))
first = first->down;
if(first != T) {
if(first->down == t1)
size = first->type->width;
@ -2867,7 +2879,7 @@ geneq(Sym *sym, Type *t)
// and calling specific equality tests for the others.
first = T;
for(t1=t->type;; t1=t1->down) {
if(t1 != T && algtype1(t1->type, nil) == AMEM) {
if(t1 != T && (isblanksym(t1->sym) || algtype1(t1->type, nil) == AMEM)) {
if(first == T)
first = t1;
continue;
@ -2875,13 +2887,16 @@ geneq(Sym *sym, Type *t)
// Run memequal for fields up to this one.
// TODO(rsc): All the calls to newname are wrong for
// cross-package unexported fields.
while(first != T && isblanksym(first->sym))
first = first->down;
if(first != T) {
if(first->down == t1) {
fn->nbody = list(fn->nbody, eqfield(np, nq, newname(first->sym), neq));
} else if(first->down->down == t1) {
fn->nbody = list(fn->nbody, eqfield(np, nq, newname(first->sym), neq));
first = first->down;
fn->nbody = list(fn->nbody, eqfield(np, nq, newname(first->sym), neq));
if(!isblanksym(first->sym))
fn->nbody = list(fn->nbody, eqfield(np, nq, newname(first->sym), neq));
} else {
// More than two fields: use memequal.
if(t1 == T)

19
test/cmp.go
View File

@ -281,6 +281,25 @@ func main() {
isfalse(ix != z)
isfalse(iz != x)
}
// structs with _ fields
{
var x = struct {
x int
_ []int
y float64
_ float64
z int
}{
x: 1, y: 2, z: 3,
}
var ix interface{} = x
istrue(x == x)
istrue(x == ix)
istrue(ix == x)
istrue(ix == ix)
}
// arrays
{

5
test/cmp6.go
View File

@ -15,6 +15,10 @@ type T3 struct{ z []int }
var t3 T3
type T4 struct { _ []int; a float64 }
var t4 T4
func main() {
// Arguments to comparison must be
// assignable one to the other (or vice versa)
@ -46,6 +50,7 @@ func main() {
// Comparison of structs should have a good message
use(t3 == t3) // ERROR "struct|expected"
use(t4 == t4) // ok; the []int is a blank field
// Slices, functions, and maps too.
var x []int