diff options
Diffstat (limited to 'src/cmd/gc/walk.c')
| -rw-r--r-- | src/cmd/gc/walk.c | 47 |
1 files changed, 46 insertions, 1 deletions
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c index b1c1c2d22..8b4fc40f2 100644 --- a/src/cmd/gc/walk.c +++ b/src/cmd/gc/walk.c @@ -2047,13 +2047,58 @@ loop: } /* + * do the export rules allow writing to this type? + * cannot be implicitly assigning to any type with + * an unavailable field. + */ +int +exportasok(Type *t) +{ + Type *f; + Sym *s; + + if(t == T) + return 1; + switch(t->etype) { + default: + // most types can't contain others; they're all fine. + break; + case TSTRUCT: + for(f=t->type; f; f=f->down) { + if(f->etype != TFIELD) + fatal("structas: not field"); + s = f->sym; + // s == nil doesn't happen for embedded fields (they get the type symbol). + // it only happens for fields in a ... struct. + if(s != nil && !exportname(s->name) && strcmp(package, s->package) != 0) { + yyerror("implicit assignment of %T field '%s'", t, s->name); + return 0; + } + if(!exportasok(f->type)) + return 0; + } + break; + + case TARRAY: + if(t->bound < 0) // slices are pointers; that's fine + break; + if(!exportasok(t->type)) + return 0; + break; + } + return 1; +} + +/* * can we assign var of type src to var of type dst */ int ascompat(Type *dst, Type *src) { - if(eqtype(dst, src)) + if(eqtype(dst, src)) { + exportasok(src); return 1; + } if(dst == T || src == T) return 0; |