cmd/gc: fix comparison of struct with _ field
Fixes #2989.
R=ken2
CC=golang-dev
https://golang.org/cl/5674091
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index bb909b9..fcbea2c 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -1172,6 +1172,7 @@
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);
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 3fd5209..5621ed9 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -571,6 +571,8 @@
}
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
@@ -888,11 +890,19 @@
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 @@
// 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 @@
// 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 @@
// 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)
diff --git a/test/cmp.go b/test/cmp.go
index 795245f..a9d0375 100644
--- a/test/cmp.go
+++ b/test/cmp.go
@@ -281,6 +281,25 @@
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
{
diff --git a/test/cmp6.go b/test/cmp6.go
index 71f1284..1e28675 100644
--- a/test/cmp6.go
+++ b/test/cmp6.go
@@ -15,6 +15,10 @@
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 @@
// 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
