runtime: make type assertion a runtime.Error, the first of many
R=r
CC=golang-dev
https://golang.org/cl/805043
diff --git a/src/pkg/runtime/386/asm.s b/src/pkg/runtime/386/asm.s
index e2eca81..862c274 100644
--- a/src/pkg/runtime/386/asm.s
+++ b/src/pkg/runtime/386/asm.s
@@ -369,20 +369,6 @@
INT $3
RET
-// callString(f, arg, out)
-// call Go f(arg), which returns a string, and store in out
-TEXT callString(SB), 7, $24
- MOVL arg+4(FP), BX
- MOVL f+0(FP), CX
- MOVL BX, 0(SP)
- CALL *CX
- MOVL out+8(FP), DI
- LEAL 4(SP), SI
- MOVSL
- MOVSL
- MOVSL
- RET
-
GLOBL m0(SB), $1024
GLOBL g0(SB), $1024
GLOBL tls0(SB), $32
diff --git a/src/pkg/runtime/Makefile b/src/pkg/runtime/Makefile
index 2ea11c0..8828426 100644
--- a/src/pkg/runtime/Makefile
+++ b/src/pkg/runtime/Makefile
@@ -21,6 +21,7 @@
CFLAGS=-I$(GOOS) -I$(GOOS)/$(GOARCH) -wF $(CFLAGS_$(SIZE)) $(CFLAGS_$(GOARCH)) $(CFLAGS_$(GOOS))
GOFILES=\
+ error.go\
extern.go\
type.go\
version.go\
diff --git a/src/pkg/runtime/amd64/asm.s b/src/pkg/runtime/amd64/asm.s
index fb32be05..9c966c5 100644
--- a/src/pkg/runtime/amd64/asm.s
+++ b/src/pkg/runtime/amd64/asm.s
@@ -311,16 +311,3 @@
INT $3
RET
-// callString(f, arg, out)
-// call Go f(arg), which returns a string, and store in out
-TEXT callString(SB), 7, $24
- MOVQ arg+8(FP), BX
- MOVQ f+0(FP), CX
- MOVQ BX, 0(SP)
- CALL *CX
- MOVQ out+16(FP), DI
- LEAQ 8(SP), SI
- MOVSQ
- MOVSQ
- RET
-
diff --git a/src/pkg/runtime/arm/asm.s b/src/pkg/runtime/arm/asm.s
index 4961045..19fa1cc 100644
--- a/src/pkg/runtime/arm/asm.s
+++ b/src/pkg/runtime/arm/asm.s
@@ -264,18 +264,3 @@
MOVW $0, R0
MOVW (R0), R1
-// callString(f, arg, out)
-// call Go f(arg), which returns a string, and store in out
-TEXT callString(SB), 7, $24
- MOVW arg+4(FP), R1
- MOVW f+0(FP), R0
- MOVW R1, 0(SP)
- BL (R0)
- MOVW 4(SP), R1
- MOVW 8(SP), R2
- MOVW 12(SP), R3
- MOVW out+8(FP), R0
- MOVW R1, 0(R0)
- MOVW R2, 4(R0)
- MOVW R3, 8(R0)
- RET
diff --git a/src/pkg/runtime/error.go b/src/pkg/runtime/error.go
new file mode 100644
index 0000000..a7d3bed
--- /dev/null
+++ b/src/pkg/runtime/error.go
@@ -0,0 +1,112 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+// The Error interface identifies a run time error.
+type Error interface {
+ String() string
+ RuntimeError() // no-op that uniquely identifies runtime.Error
+}
+
+// A TypeAssertionError explains a failed type assertion.
+type TypeAssertionError struct {
+ interfaceType Type // interface had this type
+ concreteType Type // concrete value had this type
+ assertedType Type // asserted type
+ interfaceString string
+ concreteString string
+ assertedString string
+ missingMethod string // one method needed by Interface, missing from Concrete
+}
+
+func (e *TypeAssertionError) String() string {
+ inter := e.interfaceString
+ if inter == "" {
+ inter = "interface"
+ }
+ if e.concreteType == nil {
+ return "interface conversion: " + inter + " is nil, not " + e.assertedString
+ }
+ if e.missingMethod == "" {
+ return "interface conversion: " + inter + " is " + e.concreteString +
+ ", not " + e.assertedString
+ }
+ return "interface conversion: " + e.concreteString + " is not " + e.assertedString +
+ ": missing method " + e.missingMethod
+}
+
+// Concrete returns the type of the concrete value in the failed type assertion.
+// If the interface value was nil, Concrete returns nil.
+func (e *TypeAssertionError) Concrete() Type {
+ return e.concreteType
+}
+
+// Asserted returns the type incorrectly asserted by the type assertion.
+func (e *TypeAssertionError) Asserted() Type {
+ return e.assertedType
+}
+
+// If the type assertion is to an interface type, MissingMethod returns the
+// name of a method needed to satisfy that interface type but not implemented
+// by Concrete. If there are multiple such methods,
+// MissingMethod returns one; which one is unspecified.
+// If the type assertion is not to an interface type, MissingMethod returns an empty string.
+func (e *TypeAssertionError) MissingMethod() string {
+ return e.missingMethod
+}
+
+func (*TypeAssertionError) RuntimeError() {}
+
+// For calling from C.
+func newTypeAssertionError(pt1, pt2, pt3 *Type, ps1, ps2, ps3 *string, pmeth *string, ret *interface{}) {
+ var t1, t2, t3 Type
+ var s1, s2, s3, meth string
+
+ if pt1 != nil {
+ t1 = *pt1
+ }
+ if pt2 != nil {
+ t2 = *pt2
+ }
+ if pt3 != nil {
+ t3 = *pt3
+ }
+ if ps1 != nil {
+ s1 = *ps1
+ }
+ if ps2 != nil {
+ s2 = *ps2
+ }
+ if ps3 != nil {
+ s3 = *ps3
+ }
+ if pmeth != nil {
+ meth = *pmeth
+ }
+ *ret = &TypeAssertionError{t1, t2, t3, s1, s2, s3, meth}
+}
+
+type stringer interface {
+ String() string
+}
+
+// For calling from C.
+// Prints an argument to panic.
+// There's room for arbitrary complexity here, but we keep it
+// simple and handle just a few important cases: int, string, and Stringer.
+func printany(i interface{}) {
+ switch v := i.(type) {
+ case nil:
+ print("nil")
+ case stringer:
+ print(v.String())
+ case int:
+ print(v)
+ case string:
+ print(v)
+ default:
+ print(i)
+ }
+}
diff --git a/src/pkg/runtime/iface.c b/src/pkg/runtime/iface.c
index ce42346..1af7ca7 100644
--- a/src/pkg/runtime/iface.c
+++ b/src/pkg/runtime/iface.c
@@ -46,10 +46,13 @@
Itab *m;
UncommonType *x;
Type *itype;
+ Eface err;
if(inter->mhdr.len == 0)
throw("internal error - misuse of itab");
+ locked = 0;
+
// easy case
x = type->x;
if(x == nil) {
@@ -114,9 +117,12 @@
if(!canfail) {
throw:
// didn't find method
- printf("%S is not %S: missing method %S\n",
- *type->string, *inter->string, *iname);
- throw("interface conversion");
+ ·newTypeAssertionError(nil, type, inter,
+ nil, type->string, inter->string,
+ iname, &err);
+ if(locked)
+ unlock(&ifacelock);
+ ·panic(err);
return nil; // not reached
}
m->bad = 1;
@@ -211,16 +217,21 @@
{
Itab *tab;
byte *ret;
+ Eface err;
ret = (byte*)(&i+1);
tab = i.tab;
if(tab == nil) {
- printf("interface is nil, not %S\n", *t->string);
- throw("interface conversion");
+ ·newTypeAssertionError(nil, nil, t,
+ nil, nil, t->string,
+ nil, &err);
+ ·panic(err);
}
if(tab->type != t) {
- printf("%S is %S, not %S\n", *tab->inter->string, *tab->type->string, *t->string);
- throw("interface conversion");
+ ·newTypeAssertionError(tab->inter, tab->type, t,
+ tab->inter->string, tab->type->string, t->string,
+ nil, &err);
+ ·panic(err);
}
copyout(t, &i.data, ret);
}
@@ -254,15 +265,21 @@
·ifaceE2T(Type *t, Eface e, ...)
{
byte *ret;
+ Eface err;
ret = (byte*)(&e+1);
+ if(e.type == nil) {
+ ·newTypeAssertionError(nil, nil, t,
+ nil, nil, t->string,
+ nil, &err);
+ ·panic(err);
+ }
if(e.type != t) {
- if(e.type == nil)
- printf("interface is nil, not %S\n", *t->string);
- else
- printf("interface is %S, not %S\n", *e.type->string, *t->string);
- throw("interface conversion");
+ ·newTypeAssertionError(nil, e.type, t,
+ nil, e.type->string, t->string,
+ nil, &err);
+ ·panic(err);
}
copyout(t, &e.data, ret);
}
@@ -336,12 +353,15 @@
·ifaceI2Ix(InterfaceType *inter, Iface i, Iface ret)
{
Itab *tab;
+ Eface err;
tab = i.tab;
if(tab == nil) {
// explicit conversions require non-nil interface value.
- printf("interface is nil, not %S\n", *inter->string);
- throw("interface conversion");
+ ·newTypeAssertionError(nil, nil, inter,
+ nil, nil, inter->string,
+ nil, &err);
+ ·panic(err);
} else {
ret = i;
if(tab->inter != inter)
@@ -385,12 +405,15 @@
ifaceE2I(InterfaceType *inter, Eface e, Iface *ret)
{
Type *t;
+ Eface err;
t = e.type;
if(t == nil) {
// explicit conversions require non-nil interface value.
- printf("interface is nil, not %S\n", *inter->string);
- throw("interface conversion");
+ ·newTypeAssertionError(nil, nil, inter,
+ nil, nil, inter->string,
+ nil, &err);
+ ·panic(err);
} else {
ret->data = e.data;
ret->tab = itab(inter, t, 0);
diff --git a/src/pkg/runtime/print.c b/src/pkg/runtime/print.c
index 5e4f2f5..1248432 100644
--- a/src/pkg/runtime/print.c
+++ b/src/pkg/runtime/print.c
@@ -348,68 +348,3 @@
{
write(fd, "\n", 1);
}
-
-// print an empty interface, for use by panic.
-// this could be arbitrarily complex in general,
-// so we pick off only a few important cases:
-// int, string, and values with a String() string method.
-void
-printany(Eface e)
-{
- int32 i;
- FuncType *ft;
- Method *m;
- String s;
- Type *rt;
- UncommonType *x;
-
- if(e.type == nil) {
- write(fd, "nil", 3);
- return;
- }
-
- if((x=e.type->x) != nil) {
- for(i=0; i<x->mhdr.len; i++) {
- // Look for String() string method.
- m = &x->m[i];
- if(m->name->len == 6 &&
- mcmp(m->name->str, (byte*)"String", 6) == 0 &&
- // Found String; check method signature for func() string.
- m->mtyp->kind == KindFunc &&
- (ft = (FuncType*)m->mtyp)->in.len == 0 &&
- ft->out.len == 1 &&
- // Found single output. Is it string?
- // Only base types have name != nil but pkgPath == nil.
- (rt = *(Type**)ft->out.array)->kind == KindString &&
- rt->x != nil &&
- rt->x->name != nil && rt->x->pkgPath == nil) {
- // Found the method!
- // Have to use assembly to call it
- // and save the return value.
- callString(m->ifn, e.data, &s);
- ·printstring(s);
- return;
- }
- }
- }
-
- switch(e.type->kind & ~KindNoPointers) {
- case KindInt:
- mcpy((byte*)&i, (byte*)&e.data, sizeof(i));
- ·printint(i);
- break;
-
- case KindString:
- ·printstring(*(String*)e.data);
- break;
-
- default:
- // Could print the other numeric types,
- // but that's overkill: good panics have
- // a string method anyway.
- ·printstring(*e.type->string);
- write(fd, "(???)", 5);
- break;
- }
-
-}
diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index 6001c22..3dd9977 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -935,7 +935,7 @@
printf("\t");
}
printf("panic: ");
- printany(p->arg);
+ ·printany(p->arg);
if(p->recovered)
printf(" [recovered]");
printf("\n");
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index adb8311..b4011b7 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -361,7 +361,6 @@
/*
* very low level c-called
*/
-void callString(void(*fn)(void), void *arg, String *out);
void gogo(Gobuf*, uintptr);
void gogocall(Gobuf*, void(*)(void));
uintptr gosave(Gobuf*);
@@ -372,7 +371,6 @@
void throw(int8*);
uint32 rnd(uint32, uint32);
void prints(int8*);
-void printany(Eface);
void printf(int8*, ...);
byte* mchr(byte*, byte, byte*);
void mcpy(byte*, byte*, uint32);
@@ -432,6 +430,7 @@
void gettime(int64*, int32*);
int32 callers(int32, uintptr*, int32);
int64 nanotime(void);
+void panic(int32);
#pragma varargck argpos printf 1
@@ -530,8 +529,15 @@
void runtime_printhex(uint64);
void runtime_printslice(Slice);
void runtime_printcomplex(Complex128);
-void panic(int32);
void reflect·call(byte*, byte*, uint32);
+void ·panic(Eface);
+
+/*
+ * runtime c-called (but written in Go)
+ */
+void ·newError(String, Eface*);
+void ·printany(Eface);
+void ·newTypeAssertionError(Type*, Type*, Type*, String*, String*, String*, String*, Eface*);
/*
* wrapped for go users
