Folding and check_function_arguments

This patch eliminates the arglocs array I introduced to build_over_call
in r264887, and eliminates the call to maybe_constant_value when building
"fargs" (thus retaining location wrapper nodes).

Instead, this patch requires that any checks within
check_function_arguments that need folded arguments do their own folding.

Of the various checks:
(a) check_function_nonnull already calls fold_for_warn,
(b) check_function_format doesn't need folding
(c) check_function_sentinel needs fold_for_warn in one place, which the
patch adds, and
(d) check_function_restrict needs per-argument folding, which the patch
adds.  Given that it scans before and after resetting TREE_VISITED on
each argument, it seemed best to make a copy of the array, folding each
argument from the outset, rather than repeatedly calling fold_for_warn;

gcc/c-family/ChangeLog:
	PR c++/56856
	* c-common.c (check_function_sentinel): Call fold_for_warn on the
	argument.
	(check_function_restrict): Rename param "argarray" to
	"unfolded_argarray", and make a copy named "argarray", calling
	fold_for_warn on each argument.
	(check_function_arguments): Add note about responsibility for
	folding the arguments.

gcc/cp/ChangeLog:
	PR c++/56856
	* call.c (build_over_call): Eliminate the "arglocs" array, and the
	call to maybe_constant_value when building "fargs".

From-SVN: r265609

gcc/c-family/ChangeLog

@@ -1,3 +1,14 @@
+2018-10-29  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c++/56856
+	* c-common.c (check_function_sentinel): Call fold_for_warn on the
+	argument.
+	(check_function_restrict): Rename param "argarray" to
+	"unfolded_argarray", and make a copy named "argarray", calling
+	fold_for_warn on each argument.
+	(check_function_arguments): Add note about responsibility for
+	folding the arguments.
+
 2018-10-17  Joseph Myers  <joseph@codesourcery.com>
 
 	* c-common.c (flag_isoc2x): New variable.

gcc/c-family/c-common.c

@@ -5301,7 +5301,7 @@ check_function_sentinel (const_tree fntype, int nargs, tree *argarray)
 	}
 
       /* Validate the sentinel.  */
-      sentinel = argarray[nargs - 1 - pos];
+      sentinel = fold_for_warn (argarray[nargs - 1 - pos]);
       if ((!POINTER_TYPE_P (TREE_TYPE (sentinel))
 	   || !integer_zerop (sentinel))
 	  /* Although __null (in C++) is only an integer we allow it
@@ -5320,11 +5320,16 @@ check_function_sentinel (const_tree fntype, int nargs, tree *argarray)
 
 static bool
 check_function_restrict (const_tree fndecl, const_tree fntype,
-			 int nargs, tree *argarray)
+			 int nargs, tree *unfolded_argarray)
 {
   int i;
   tree parms = TYPE_ARG_TYPES (fntype);
 
+  /* Call fold_for_warn on all of the arguments.  */
+  auto_vec<tree> argarray (nargs);
+  for (i = 0; i < nargs; i++)
+    argarray.quick_push (fold_for_warn (unfolded_argarray[i]));
+
   if (fndecl
       && TREE_CODE (fndecl) == FUNCTION_DECL)
     {
@@ -5361,7 +5366,7 @@ check_function_restrict (const_tree fndecl, const_tree fntype,
       if (POINTER_TYPE_P (type)
 	  && TYPE_RESTRICT (type)
 	  && !TYPE_READONLY (TREE_TYPE (type)))
-	warned |= warn_for_restrict (i, argarray, nargs);
+	warned |= warn_for_restrict (i, argarray.address (), nargs);
     }
 
   for (i = 0; i < nargs; i++)
@@ -5608,7 +5613,11 @@ attribute_fallthrough_p (tree attr)
 /* Check for valid arguments being passed to a function with FNTYPE.
    There are NARGS arguments in the array ARGARRAY.  LOC should be used
    for diagnostics.  Return true if either -Wnonnull or -Wrestrict has
-   been issued.  */
+   been issued.
+
+   The arguments in ARGARRAY may not have been folded yet (e.g. for C++,
+   to preserve location wrappers); checks that require folded arguments
+   should call fold_for_warn on them.  */
 
 bool
 check_function_arguments (location_t loc, const_tree fndecl, const_tree fntype,

gcc/cp/ChangeLog

@@ -1,3 +1,9 @@
+2018-10-29  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c++/56856
+	* call.c (build_over_call): Eliminate the "arglocs" array, and the
+	call to maybe_constant_value when building "fargs".
+
 2018-10-29  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* decl.c (create_array_type_for_decl): Add location_t parameter

gcc/cp/call.c

@@ -8198,7 +8198,6 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
     {
       tree *fargs = (!nargs ? argarray
 			    : (tree *) alloca (nargs * sizeof (tree)));
-      auto_vec<location_t> arglocs (nargs);
       for (j = 0; j < nargs; j++)
 	{
 	  /* For -Wformat undo the implicit passing by hidden reference
@@ -8207,12 +8206,11 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
 	      && TYPE_REF_P (TREE_TYPE (argarray[j])))
 	    fargs[j] = TREE_OPERAND (argarray[j], 0);
 	  else
-	    fargs[j] = maybe_constant_value (argarray[j]);
+	    fargs[j] = argarray[j];
-	  arglocs.quick_push (EXPR_LOC_OR_LOC (argarray[j], input_location));
 	}
 
       warned_p = check_function_arguments (input_location, fn, TREE_TYPE (fn),
-					   nargs, fargs, &arglocs);
+					   nargs, fargs, NULL);
     }
 
   if (DECL_INHERITED_CTOR (fn))