stricter interface conversion rule: i.(T)

must have non-nil i.

R=ken
OCL=29136
CL=29136

diff --git a/src/cmd/gc/builtin.c.boot b/src/cmd/gc/builtin.c.boot
index 164a27822cb576f234eb324246758704e2dc76e7..38c8b4cb5e34fb021c2b75def1925e5a00c1a468 100644 (file)
--- a/src/cmd/gc/builtin.c.boot
+++ b/src/cmd/gc/builtin.c.boot
@@ -32,6 +32,7 @@ char *sysimport =
        "func sys.ifaceI2T (sigt *uint8, iface any) (ret any)\n"
        "func sys.ifaceI2T2 (sigt *uint8, iface any) (ret any, ok bool)\n"
        "func sys.ifaceI2I (sigi *uint8, iface any) (ret any)\n"
+       "func sys.ifaceI2Ix (sigi *uint8, iface any) (ret any)\n"
        "func sys.ifaceI2I2 (sigi *uint8, iface any) (ret any, ok bool)\n"
        "func sys.ifaceeq (i1 any, i2 any) (ret bool)\n"
        "func sys.efaceeq (i1 any, i2 any) (ret bool)\n"

diff --git a/src/cmd/gc/sys.go b/src/cmd/gc/sys.go
index e139e759c603ccc91db3e559f3769f31e93c54e8..b5a6ddc2bb2775222fa09a13e3451013b6c83425 100644 (file)
--- a/src/cmd/gc/sys.go
+++ b/src/cmd/gc/sys.go
@@ -42,6 +42,7 @@ func  ifaceT2I(sigi *byte, sigt *byte, elem any) (ret any);
 func   ifaceI2T(sigt *byte, iface any) (ret any);
 func   ifaceI2T2(sigt *byte, iface any) (ret any, ok bool);
 func   ifaceI2I(sigi *byte, iface any) (ret any);
+func   ifaceI2Ix(sigi *byte, iface any) (ret any);
 func   ifaceI2I2(sigi *byte, iface any) (ret any, ok bool);
 func   ifaceeq(i1 any, i2 any) (ret bool);
 func   efaceeq(i1 any, i2 any) (ret bool);

diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 18cd2c7eb618031cd40133e936eb1a3438d4b881..0f160a8a4cc7ff23af80e2ac00e973209f95ac18 100644 (file)
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -12,6 +12,7 @@ enum
        I2T,
        I2T2,
        I2I,
+       I2Ix,
        I2I2,
        T2I,
        I2Isame,
@@ -524,7 +525,7 @@ loop:
                                case I2T:
                                        et = I2T2;
                                        break;
-                               case I2I:
+                               case I2Ix:
                                        et = I2I2;
                                        break;
                                case E2I:
@@ -2947,6 +2948,8 @@ ifaceas1(Type *dst, Type *src, int explicit)
                        ifacecheck(dst, src, lineno, explicit);
                        if(isnilinter(src))
                                return E2I;
+                       if(explicit)
+                               return I2Ix;
                        return I2I;
                }
                if(isnilinter(dst))
@@ -2983,6 +2986,7 @@ ifacename[] =
        [I2T]           = "ifaceI2T",
        [I2T2]          = "ifaceI2T2",
        [I2I]           = "ifaceI2I",
+       [I2Ix]          = "ifaceI2Ix",
        [I2I2]          = "ifaceI2I2",
        [I2Isame]       = "ifaceI2Isame",
        [E2T]           = "ifaceE2T",
@@ -3038,6 +3042,7 @@ ifacecvt(Type *tl, Node *n, int et)
        case I2T:
        case I2T2:
        case I2I:
+       case I2Ix:
        case I2I2:
        case E2T:
        case E2T2:

diff --git a/src/runtime/iface.c b/src/runtime/iface.c
index 9e65a267aa0144357c66105220f3a2c07a827e06..2351f422d07d9367a9dd7a7a8ff87eeddbf0ffb6 100644 (file)
--- a/src/runtime/iface.c
+++ b/src/runtime/iface.c
@@ -431,6 +431,7 @@ sys·ifaceI2E(Iface i, Eface ret)
 }
 
 // ifaceI2I(sigi *byte, iface any) (ret any);
+// called only for implicit (no type assertion) conversions
 void
 sys·ifaceI2I(Sigi *si, Iface i, Iface ret)
 {
@@ -438,7 +439,6 @@ sys·ifaceI2I(Sigi *si, Iface i, Iface ret)
 
        im = i.type;
        if(im == nil) {
-//TODO(rsc): fixme
                // If incoming interface is uninitialized (zeroed)
                // make the outgoing interface zeroed as well.
                ret = niliface;
@@ -451,6 +451,27 @@ sys·ifaceI2I(Sigi *si, Iface i, Iface ret)
        FLUSH(&ret);
 }
 
+// ifaceI2Ix(sigi *byte, iface any) (ret any);
+// called only for explicit conversions (with type assertion).
+void
+sys·ifaceI2Ix(Sigi *si, Iface i, Iface ret)
+{
+       Itype *im;
+
+       im = i.type;
+       if(im == nil) {
+               // explicit conversions require non-nil interface value.
+               printf("interface is nil, not %s\n", si->name);
+               throw("interface conversion");
+       } else {
+               ret = i;
+               if(im->sigi != si)
+                       ret.type = itype(si, im->sigt, 0);
+       }
+
+       FLUSH(&ret);
+}
+
 // ifaceI2I2(sigi *byte, iface any) (ret any, ok bool);
 void
 sys·ifaceI2I2(Sigi *si, Iface i, Iface ret, bool ok)
@@ -458,14 +479,13 @@ sys·ifaceI2I2(Sigi *si, Iface i, Iface ret, bool ok)
        Itype *im;
 
        im = i.type;
-       ok = true;
        if(im == nil) {
-//TODO: fixme
-               // If incoming interface is uninitialized (zeroed)
-               // make the outgoing interface zeroed as well.
+               // If incoming interface is nil, the conversion fails.
                ret = niliface;
+               ok = false;
        } else {
                ret = i;
+               ok = true;
                if(im->sigi != si) {
                        ret.type = itype(si, im->sigt, 1);
                        if(ret.type == nil) {
@@ -480,6 +500,7 @@ sys·ifaceI2I2(Sigi *si, Iface i, Iface ret, bool ok)
 }
 
 // ifaceE2I(sigi *byte, iface any) (ret any);
+// Called only for explicit conversions (with type assertion).
 void
 sys·ifaceE2I(Sigi *si, Eface e, Iface ret)
 {
@@ -487,8 +508,9 @@ sys·ifaceE2I(Sigi *si, Eface e, Iface ret)
 
        t = e.type;
        if(t == nil) {
-//TODO(rsc): fixme
-               ret = niliface;
+               // explicit conversions require non-nil interface value.
+               printf("interface is nil, not %s\n", si->name);
+               throw("interface conversion");
        } else {
                ret.data = e.data;
                ret.type = itype(si, t, 0);
@@ -505,8 +527,9 @@ sys·ifaceE2I2(Sigi *si, Eface e, Iface ret, bool ok)
        t = e.type;
        ok = true;
        if(t == nil) {
-//TODO(rsc): fixme
+               // If incoming interface is nil, the conversion fails.
                ret = niliface;
+               ok = false;
        } else {
                ret.data = e.data;
                ret.type = itype(si, t, 1);