[Bug fortran/68815] New: Error/warning diagnostic: '%s' should be converted to %qs-like or %<%s%>-like string strings

["burnus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68815

            Bug ID: 68815
           Summary: Error/warning diagnostic: '%s' should be converted to
                    %qs-like or %<%s%>-like string strings
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

Fortran has code like:

   sprintf (msg, _("Unknown operator '%s' at %%L"), ...

Expected: The strings are handled like %qs, i.e. the proper quotes are used.
(Of cause, except for run-time errors.)

In several cases - as in this one - the code enters as fmt string of a
diagnostic function (visible as %%L is used). In those cases, '%s' can be
replaced by %%<%s%%>.

The question is how to deal with those strings (if any), which enter as
argument to "%s" and are used as verbatim.

(When working on it: Don't convert strings used by the run-time diagnostic.)

 * * *

Related but simpler: The following goes as fmt string directly into the
diagnostic system and can thus simply be applied (untested):

--- a/gcc/fortran/check.c
+++ b/gcc/fortran/check.c
@@ -3866 +3866 @@ gfc_check_reshape (gfc_expr *source, gfc_expr *shape,
-                            "%<%d%> duplicated)",
+                            "%qd duplicated)",
--- a/gcc/fortran/decl.c
+++ b/gcc/fortran/decl.c
@@ -1197 +1197 @@ gfc_verify_c_interop_param (gfc_symbol *sym)
-                                 "procedure '%s' at %L", sym->name, 
+                                 "procedure %qs at %L", sym->name,
@@ -2026 +2026 @@ variable_decl (int elem)
-         gfc_error ("'%s' at %C is a redefinition of the declaration "
+         gfc_error ("%qs at %C is a redefinition of the declaration "
@@ -2028 +2028 @@ variable_decl (int elem)
-                    "PROCEDURE '%s'", sym->name,
+                    "PROCEDURE %qs", sym->name,
--- a/gcc/fortran/io.c
+++ b/gcc/fortran/io.c
@@ -552 +552 @@ check_format (bool is_input)
-  const char *unexpected_element  = _("Unexpected element %<%c%> in format "
+  const char *unexpected_element  = _("Unexpected element %qc in format "
--- a/gcc/fortran/symbol.c
+++ b/gcc/fortran/symbol.c
@@ -168 +168 @@ gfc_add_new_implicit_range (int c1, int c2)
-         gfc_error ("Letter %<%c%> already set in IMPLICIT statement at %C",
+         gfc_error ("Letter %qc already set in IMPLICIT statement at %C",
@@ -468 +468 @@ check_conflict (symbol_attribute *attr, const char *name, locus
*where)
-    gfc_error_now ("internal procedure '%s' at %L conflicts with "
+    gfc_error_now ("internal procedure %qs at %L conflicts with "
--- a/gcc/fortran/trans-common.c
+++ b/gcc/fortran/trans-common.c
@@ -1169 +1169 @@ translate_common (gfc_common_head *common, gfc_symbol
*var_list)
-      gfc_error ("COMMON '%s' at %L does not exist",
+      gfc_error ("COMMON %qs at %L does not exist",