runtime: distinct panic message for call of nil func value

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/5531062

src/pkg/runtime/thread_darwin.c

@@ -382,13 +382,19 @@ runtime·sigpanic(void)
 {
 	switch(g->sig) {
 	case SIGBUS:
-		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000)
+		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGSEGV:
-		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000)
+		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGFPE:

src/pkg/runtime/thread_freebsd.c

@@ -128,13 +128,19 @@ runtime·sigpanic(void)
 {
 	switch(g->sig) {
 	case SIGBUS:
-		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000)
+		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGSEGV:
-		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000)
+		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGFPE:

src/pkg/runtime/thread_linux.c

@@ -184,13 +184,19 @@ runtime·sigpanic(void)
 {
 	switch(g->sig) {
 	case SIGBUS:
-		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000)
+		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
+			}
 			runtime·panicstring("invalid memory address or nil pointer dereference");
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGSEGV:
-		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000)
+		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGFPE:

src/pkg/runtime/thread_netbsd.c

@@ -175,13 +175,19 @@ runtime·sigpanic(void)
 {
 	switch(g->sig) {
 	case SIGBUS:
-		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000)
+		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGSEGV:
-		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000)
+		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGFPE:

src/pkg/runtime/thread_openbsd.c

@@ -175,13 +175,19 @@ runtime·sigpanic(void)
 {
 	switch(g->sig) {
 	case SIGBUS:
-		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000)
+		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGSEGV:
-		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000)
+		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case SIGFPE:

src/pkg/runtime/thread_windows.c

@@ -270,8 +270,11 @@ runtime·sigpanic(void)
 {
 	switch(g->sig) {
 	case EXCEPTION_ACCESS_VIOLATION:
-		if(g->sigcode1 < 0x1000)
+		if(g->sigcode1 < 0x1000) {
+			if(g->sigpc == 0)
+				runtime·panicstring("call of nil func value");
 			runtime·panicstring("invalid memory address or nil pointer dereference");
+		}
 		runtime·printf("unexpected fault address %p\n", g->sigcode1);
 		runtime·throw("fault");
 	case EXCEPTION_INT_DIVIDE_BY_ZERO: