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cmd/gc: don't dereference a nil Type pointer in widstruct

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The nil dereference in the next few lines doesn't seem
to cause a segmentation fault on Unix, but does seem
to halt the Go compiler.

The following is a test case:

>>>
package main

func mine(int b) int {
        return b + 2
}

func main() {
        mine()

        c = mine()
}
<<<

Without this change only the following is caught:

typecheck.go:3: undefined: b
typecheck.go:4: undefined: b

with it, we catch all the errors:

typecheck.go:3: undefined: b
typecheck.go:4: undefined: b
typecheck.go:10: undefined: c
typecheck.go:10: cannot assign to c .

R=rsc, minux.ma
CC=golang-dev
https://golang.org/cl/6542060
This commit is contained in:
Akshat Kumar 2012-10-07 14:11:59 +08:00 committed by Shenghou Ma
parent a45777fe99
commit 51e8fe5b1b
2 changed files with 20 additions and 0 deletions
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2
src/cmd/gc/align.c
View File

@ -54,6 +54,8 @@ widstruct(Type *errtype, Type *t, vlong o, int flag)
for(f=t->type; f!=T; f=f->down) {
if(f->etype != TFIELD)
fatal("widstruct: not TFIELD: %lT", f);
if(f->type == T)
break;
dowidth(f->type);
if(f->type->align > maxalign)
maxalign = f->type->align;

18
test/typecheck.go Normal file
View File

@ -0,0 +1,18 @@
// errorcheck
// Verify that the Go compiler will not
// die after running into an undefined
// type in the argument list for a
// function.
// Does not compile.
package main
func mine(int b) int { // ERROR "undefined.*b"
return b + 2 // ERROR "undefined.*b"
}
func main() {
mine()
c = mine() // ERROR "undefined.*c" "cannot assign to c"
}