https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85526
--- Comment #6 from Steve Kargl <sgk at troutmask dot apl.washington.edu> --- On Thu, Apr 26, 2018 at 12:54:05AM +0000, sgk at troutmask dot apl.washington.edu wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85526 > > --- Comment #3 from Steve Kargl <sgk at troutmask dot apl.washington.edu> --- > On Wed, Apr 25, 2018 at 11:33:34PM +0000, dominiq at lps dot ens.fr wrote: > > The code compiles with 6.4.0 and 7.3.0, but not with 6.4.1, 7.3.1, > > 8.0.1 and trunk (9.0). This is likely r258347 for gcc8, r258367 > > for gcc7, and r258368 for gcc6. > > Bummer. > > Don't know how to fix this one. > > Workaround is to move checkFmt() to above its first use > in another function. > Well, I understand the problem a bit now. In decl.c (lines 3229 to 3248), we have /* If gfortran ends up here, then the len may be reducible to a constant. Try to do that here. If it does not reduce, simply assign len to the charlen. */ if (len && len->expr_type != EXPR_CONSTANT) { gfc_expr *e; e = gfc_copy_expr (len); gfc_reduce_init_expr (e); if (e->expr_type == EXPR_CONSTANT) { gfc_replace_expr (len, e); if (mpz_cmp_si (len->value.integer, 0) < 0) mpz_set_ui (len->value.integer, 0); } else { gfc_free_expr (e); } cl->length = len; } 'gfc_reduce_init_expr (e)' is causing the symbol checkFmt, which has not previously been seen, to be committed to the current namespace before the symbol has been resolved. So, checkFmt() doesn't have a proper type and gfortran cannot set it when she finally parses the function. During the translation, checkFmt is implicitly typed, which can be gleaned from 0x6ce630 gfc_conv_expr(gfc_se*, gfc_expr*) ../../gcc8/gcc/fortran/trans-expr.c:7918 0x6d0967 gfc_conv_expr_val(gfc_se*, gfc_expr*) <-- from stepping in gdb ../../gcc8/gcc/fortran/trans-expr.c:7975 0x6fed87 gfc_trans_if_1 ../../gcc8/gcc/fortran/trans-stmt.c:1427 0x70715a gfc_trans_if(gfc_code*) What needs to be done is that symbols in the gfc_current_ns must be save before the call to 'gfc_reduce_init_expr (e)'. If reduction fails, then the old symbols need to be restored in the gfc_current_ns and any new symbols added by 'gfc_reduce_init_expr (e)' need to be removed. Unfortunately, I don't know how to do this.
