The attach patch properly sets the length for a zero length string in a data. Built and regression tested on x86_64-*-freebsd. The testcase is self-explanatory.
OK to commit? 2015-10-21 Steven G. Kargl <ka...@gcc.gnu.org> PR fortran/67939 * data.c (create_character_initializer): Deal with zero length string. 2015-10-21 Steven G. Kargl <ka...@gcc.gnu.org> PR fortran/67939 * gfortran.dg/pr67939.f90: New test. -- Steve
Index: gcc/fortran/data.c =================================================================== --- gcc/fortran/data.c (revision 229138) +++ gcc/fortran/data.c (working copy) @@ -104,7 +104,7 @@ static gfc_expr * create_character_initializer (gfc_expr *init, gfc_typespec *ts, gfc_ref *ref, gfc_expr *rvalue) { - int len, start, end; + int len, start, end, tlen; gfc_char_t *dest; bool alloced_init = false; @@ -162,12 +162,22 @@ create_character_initializer (gfc_expr * else len = rvalue->value.character.length; - if (len > end - start) + tlen = end - start; + if (len > tlen) { - gfc_warning_now (0, "Initialization string starting at %L was " - "truncated to fit the variable (%d/%d)", - &rvalue->where, end - start, len); - len = end - start; + if (tlen < 0) + { + gfc_warning_now (0, "Unused initialization string at %L because " + "variable has zero length", &rvalue->where); + len = 0; + } + else + { + gfc_warning_now (0, "Initialization string at %L was truncated to " + "fit the variable (%d/%d)", &rvalue->where, + tlen, len); + len = tlen; + } } if (rvalue->ts.type == BT_HOLLERITH) @@ -181,7 +191,7 @@ create_character_initializer (gfc_expr * len * sizeof (gfc_char_t)); /* Pad with spaces. Substrings will already be blanked. */ - if (len < end - start && ref == NULL) + if (len < tlen && ref == NULL) gfc_wide_memset (&dest[start + len], ' ', end - (start + len)); if (rvalue->ts.type == BT_HOLLERITH) Index: gcc/testsuite/gfortran.dg/pr67939.f90 =================================================================== --- gcc/testsuite/gfortran.dg/pr67939.f90 (revision 0) +++ gcc/testsuite/gfortran.dg/pr67939.f90 (working copy) @@ -0,0 +1,21 @@ +! { dg-do compile } +! PR fortran/67939 +! Original code by Gerhard Steinmetz +! gerhard dot steinmetz dot fortran at t-online dot de +! +program p + character(100) :: x + data x(998:99) /'ab'/ ! { dg-warning "Unused initialization string" } + call a +end + +subroutine a + character(2) :: x + data x(:-1) /'ab'/ ! { dg-warning "Unused initialization string" } +end subroutine a + +subroutine b + character(8) :: x + data x(3:1) /'abc'/ ! { dg-warning "Unused initialization string" } +end subroutine b +