C++: more location wrapper nodes (PR c++/43064, PR c++/43486)

This is v6 of the patch, as posted to:
  https://gcc.gnu.org/ml/gcc-patches/2018-12/msg01331.html


The C++ frontend gained various location wrapper nodes in r256448 (GCC 8).
That patch:
  https://gcc.gnu.org/ml/gcc-patches/2018-01/msg00799.html
added wrapper nodes around all nodes with !CAN_HAVE_LOCATION_P for:

* arguments at callsites, and for

* typeid, alignof, sizeof, and offsetof.

This is a followup to that patch, adding many more location wrappers
to the C++ frontend.  It adds location wrappers for nodes with
!CAN_HAVE_LOCATION_P to:

* all literal nodes (in cp_parser_primary_expression)

* all id-expression nodes (in finish_id_expression), except within a
  decltype.

* all mem-initializer nodes within a mem-initializer-list
  (in cp_parser_mem_initializer)

However, the patch also adds some suppressions: regions in the parser
for which wrapper nodes will not be created:

* within a template-parameter-list or template-argument-list (in
  cp_parser_template_parameter_list and cp_parser_template_argument_list
  respectively), to avoid encoding the spelling location of the nodes
  in types.  For example, "array<10>" and "array<10>" are the same type,
  despite the fact that the two different "10" tokens are spelled in
  different locations in the source.

* within a gnu-style attribute (none of are handlers are set up to cope
  with location wrappers yet)

* within various OpenMP clauses

The patch enables various improvements to locations for bad
initializations, for -Wchar-subscripts, and enables various other
improvements in the followup patch.

For example, given the followup buggy mem-initializer:

class X {
  X() : bad(42),
        good(42)
  { }
  void* bad;
  int good;
};

previously, our diagnostic was on the final close parenthesis of the
mem-initializer-list, leaving it unclear where the problem is:

t.cc: In constructor 'X::X()':
t.cc:3:16: error: invalid conversion from 'int' to 'void*' [-fpermissive]
    3 |         good(42)
      |                ^
      |                |
      |                int

whereas with the patch we highlight which expression is bogus:

t.cc: In constructor 'X::X()':
t.cc:2:13: error: invalid conversion from 'int' to 'void*' [-fpermissive]
    2 |   X() : bad(42),
      |             ^~
      |             |
      |             int

Similarly, the diagnostic for this bogus initialization:

i.cc:1:44: error: initializer-string for array of chars is too long [-fpermissive]
    1 | char test[3][4] = { "ok", "too long", "ok" };
      |                                            ^

is improved by the patch so that it indicates which string is too long:

i.cc:1:27: error: initializer-string for array of chars is too long [-fpermissive]
    1 | char test[3][4] = { "ok", "too long", "ok" };
      |                           ^~~~~~~~~~


gcc/c-family/ChangeLog:
	PR c++/43064
	PR c++/43486
	* c-common.c (unsafe_conversion_p): Fold any location wrapper.
	(verify_tree): Handle location wrappers.
	(c_common_truthvalue_conversion): Strip any location wrapper.
	Handle CONST_DECL.
	(fold_offsetof): Strip any location wrapper.
	(complete_array_type): Likewise for initial_value.
	(convert_vector_to_array_for_subscript): Call fold_for_warn on the
	index before checking for INTEGER_CST.
	* c-pretty-print.c (c_pretty_printer::primary_expression): Don't
	print parentheses around location wrappers.
	* c-warn.c (warn_logical_operator): Call fold_for_warn on op_right
	before checking for INTEGER_CST.
	(warn_tautological_bitwise_comparison): Call
	tree_strip_any_location_wrapper on lhs, rhs, and bitop's operand
	before checking for INTEGER_CST.
	(readonly_error): Strip any location wrapper.
	(warn_array_subscript_with_type_char): Strip location wrappers
	before checking for INTEGER_CST.  Use the location of the index if
	available.

gcc/ChangeLog:
	PR c++/43064
	PR c++/43486
	* convert.c: Include "selftest.h".
	(preserve_any_location_wrapper): New function.
	(convert_to_pointer_maybe_fold): Update to handle location
	wrappers.
	(convert_to_real_maybe_fold): Likewise.
	(convert_to_integer_1): Strip expr when using TREE_OVERFLOW.
	Handle location wrappers when checking for INTEGER_CST.
	(convert_to_integer_maybe_fold): Update to handle location
	wrappers.
	(convert_to_complex_maybe_fold): Likewise.
	(selftest::test_convert_to_integer_maybe_fold): New functions.
	(selftest::convert_c_tests): New function.
	* convert.h (preserve_any_location_wrapper): New decl.
	* fold-const.c (size_binop_loc): Strip location wrappers when
	using TREE_OVERFLOW.
	(operand_equal_p): Strip any location wrappers.
	(integer_valued_real_p): Strip any location wrapper.
	* selftest-run-tests.c (selftest::run_tests): Call
	selftest::convert_c_tests.
	* selftest.h (selftest::convert_c_tests): New decl.
	* tree.c (build_complex): Assert that REAL and IMAG are constants.
	(integer_zerop): Look through location wrappers.
	(integer_onep): Likewise.
	(integer_each_onep): Likewise.
	(integer_all_onesp): Likewise.
	(integer_minus_onep): Likewise.
	(integer_pow2p): Likewise.
	(integer_nonzerop): Likewise.
	(integer_truep): Likewise.
	(fixed_zerop): Likewise.
	(real_zerop): Likewise.
	(real_onep): Likewise.
	(real_minus_onep): Likewise.
	(tree_int_cst_equal): Likewise.
	(simple_cst_equal): Treat location wrappers with non-equal source
	locations as being unequal.
	(uniform_integer_cst_p): Look through location wrappers.
	(maybe_wrap_with_location): Don't create wrappers if any
	auto_suppress_location_wrappers are active.
	(suppress_location_wrappers): New variable.
	(selftest::test_predicates): New test.
	(selftest::tree_c_tests): Call it.
	* tree.h (CONSTANT_CLASS_OR_WRAPPER_P): New macro.
	(suppress_location_wrappers): New decl.
	(class auto_suppress_location_wrappers): New class.

gcc/cp/ChangeLog:
	PR c++/43064
	PR c++/43486
	* call.c (build_conditional_expr_1): Strip location wrappers when
	checking for CONST_DECL.
	(conversion_null_warnings): Use location of "expr" if available.
	* class.c (fixed_type_or_null): Handle location wrappers.
	* constexpr.c (potential_constant_expression_1): Likewise.
	* cvt.c (ignore_overflows): Strip location wrappers when
	checking for INTEGER_CST, and re-wrap the result if present.
	(ocp_convert): Call fold_for_warn before checking for INTEGER_CST.
	* decl.c (reshape_init_r): Strip any location wrapper.
	(undeduced_auto_decl): Likewise.
	* expr.c (mark_discarded_use): Likewise for expr.
	* init.c (build_aggr_init): Likewise before checking init for
	DECL_P.
	(warn_placement_new_too_small): Call fold_for_warn on adj before
	checking for CONSTANT_CLASS_P, and on nelts.  Strip any location
	wrapper from op0 and on oper before checking for VAR_P.
	* parser.c (cp_parser_primary_expression): Call
	maybe_add_location_wrapper on numeric and string literals.
	(cp_parser_postfix_expression): Strip any location wrapper when
	checking for DECL_IS_BUILTIN_CONSTANT_P.
	(cp_parser_unary_expression): Ensure that folding of NEGATE_EXPR
	around a constant happens in the presence of location wrappers and
	returns a wrapped result.
	(cp_parser_has_attribute_expression): Strip any location wrapper
	from "oper".
	(cp_parser_binary_expression): Strip any location wrapper when
	checking for DECL_P on the lhs.
	(cp_parser_decltype): Strip any location wrapper from result of
	cp_parser_decltype_expr.
	(cp_parser_mem_initializer): Add location wrappers to the
	parenthesized expression list.
	(cp_parser_template_parameter_list): Don't create wrapper nodes
	within a template-parameter-list.
	(cp_parser_template_argument_list): Don't create wrapper nodes
	within a template-argument-list.
	(cp_parser_parameter_declaration): Strip location wrappers from
	default arguments.
	(cp_parser_gnu_attribute_list): Don't create wrapper nodes.
	(cp_parser_std_attribute_spec_seq): Likewise.
	(cp_parser_omp_all_clauses): Don't create wrapper nodes within
	OpenMP clauses.
	(cp_parser_omp_for_loop): Likewise.
	(cp_parser_omp_declare_reduction_exprs): Likewise.
	* pt.c (convert_nontype_argument_function): Strip location
	wrappers from fn_no_ptr before checking for FUNCTION_DECL.
	(tsubst_default_argument): Move note about which callsite led to
	instantiation to after the check_default_argument call.
	(do_auto_deduction): Likewise from init before checking for
	DECL_P.
	* semantics.c (force_paren_expr): Likewise from expr before
	checking for DECL_P.
	(finish_parenthesized_expr): Likewise from expr before
	checking for STRING_CST.
	(perform_koenig_lookup): Likewise from fn.
	(finish_call_expr): Likewise.
	(finish_id_expression): Rename to...
	(finish_id_expression_1): ...this, calling
	maybe_add_location_wrapper on the result.
	(capture_decltype): Use lookup_name_real rather than value_member
	when looking up decl within the capture-list.
	* tree.c (cp_stabilize_reference): Strip any location wrapper.
	(builtin_valid_in_constant_expr_p): Likewise.
	(strip_typedefs_expr): Strip any location wrapper before checking
	for decls or constants.
	(is_overloaded_fn): Likewise.
	(maybe_get_fns): Likewise.
	(selftest::test_lvalue_kind): Verify lvalue_p.
	* typeck.c (cxx_sizeof_expr): Strip any location wrapper.
	(cxx_alignof_expr): Likewise.
	(is_bitfield_expr_with_lowered_type): Handle location wrappers.
	(cp_build_array_ref): Call maybe_constant_value on "idx".
	(cp_build_binary_op): Strip location wrapper from first_arg before
	checking for PARM_DECL.  Likewise for op1 before checking for
	INTEGER_CST in two places.  Likewise for orig_op0 and orig_op1
	when checking for STRING_CST.
	(cp_build_addr_expr_1): Likewise for arg when checking for
	FUNCTION_DECL.
	(cp_build_modify_expr): Likewise for newrhs when checking for
	STRING_CST.
	(convert_for_assignment): Don't strip location wrappers when
	stripping NON_LVALUE_EXPR.
	(maybe_warn_about_returning_address_of_local): Strip location
	wrapper from whats_returned before checking for DECL_P.
	(can_do_nrvo_p): Strip location wrapper from retval.
	(treat_lvalue_as_rvalue_p): Likewise.
	(check_return_expr): Likewise.
	* typeck2.c (cxx_incomplete_type_diagnostic): Strip location
	wrapper from value before checking for VAR_P or PARM_DECL.
	(digest_init_r): Strip location wrapper from init.  When
	copying "init", also copy the wrapped node.

gcc/objc/ChangeLog:
	PR c++/43064
	PR c++/43486
	* objc-act.c (objc_maybe_build_component_ref): Strip any location
	wrapper before checking for UOBJC_SUPER_decl and self_decl.
	(objc_finish_message_expr): Strip any location wrapper.
	(gen_declaration): Strip location wrappers from "w".

gcc/testsuite/ChangeLog:
	PR c++/43064
	PR c++/43486
	* c-c++-common/pr51712.c (valid2): Mark xfail as passing on C++.
	* g++.dg/cpp0x/constexpr-47969.C: Update column of expected error.
	* g++.dg/cpp0x/constexpr-ex2.C: Likewise.
	* g++.dg/cpp0x/scoped_enum2.C: Likewise.
	* g++.dg/cpp1z/decomp48.C: Update expected location of warning
	for named local variables to use that of the local variable.
	* g++.dg/ext/vla1.C: Update column.
	* g++.dg/init/array43.C: Update expected column to be that of the
	initializer.
	* g++.dg/init/initializer-string-too-long.C: New test.
	* g++.dg/init/new44.C: Add "-ftrack-macro-expansion=0".
	* g++.dg/init/pr43064-1.C: New test.
	* g++.dg/init/pr43064-2.C: New test.
	* g++.dg/init/pr43064-3.C: New test.
	* g++.dg/other/fold1.C: Update column of expected error.
	* g++.dg/parse/crash36.C: Likewise.
	* g++.dg/plugin/diagnostic-test-expressions-1.C: Add negative
	integer and float expressions.
	* g++.dg/template/defarg6.C: Move expected error to the default
	argument; add expected message about where instantiated.
	* g++.dg/wrappers/Wparentheses.C: New test.
	* g++.old-deja/g++.bugs/900402_02.C: Update column of expected
	error.

From-SVN: r267272

1 files changed, 58 insertions, 17 deletions

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index b57e35d..c0552b5 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -5232,7 +5232,8 @@ cp_parser_primary_expression (cp_parser *parser,
 	  if (!cast_p)
 	    cp_parser_non_integral_constant_expression (parser, NIC_FLOAT);
 	}
-      return cp_expr (token->u.value, token->location);
+      return (cp_expr (token->u.value, token->location)
+	      .maybe_add_location_wrapper ());
 
     case CPP_CHAR_USERDEF:
     case CPP_CHAR16_USERDEF:
@@ -5254,9 +5255,10 @@ cp_parser_primary_expression (cp_parser *parser,
       /* ??? Should wide strings be allowed when parser->translate_strings_p
 	 is false (i.e. in attributes)?  If not, we can kill the third
 	 argument to cp_parser_string_literal.  */
-      return cp_parser_string_literal (parser,
-				       parser->translate_strings_p,
-				       true);
+      return (cp_parser_string_literal (parser,
+					parser->translate_strings_p,
+					true)
+	      .maybe_add_location_wrapper ());
 
     case CPP_OPEN_PAREN:
       /* If we see `( { ' then we are looking at the beginning of
@@ -7169,8 +7171,10 @@ cp_parser_postfix_expression (cp_parser *parser, bool address_p, bool cast_p,
 
             is_member_access = false;
 
+	    tree stripped_expression
+	      = tree_strip_any_location_wrapper (postfix_expression);
 	    is_builtin_constant_p
-	      = DECL_IS_BUILTIN_CONSTANT_P (postfix_expression);
+	      = DECL_IS_BUILTIN_CONSTANT_P (stripped_expression);
 	    if (is_builtin_constant_p)
 	      {
 		/* The whole point of __builtin_constant_p is to allow
@@ -8363,18 +8367,22 @@ cp_parser_unary_expression (cp_parser *parser, cp_id_kind * pidk,
 	case NEGATE_EXPR:
 	  /* Immediately fold negation of a constant, unless the constant is 0
 	     (since -0 == 0) or it would overflow.  */
-	  if (unary_operator == NEGATE_EXPR && op_ttype == CPP_NUMBER
-	      && CONSTANT_CLASS_P (cast_expression)
-	      && !integer_zerop (cast_expression)
-	      && !TREE_OVERFLOW (cast_expression))
+	  if (unary_operator == NEGATE_EXPR && op_ttype == CPP_NUMBER)
 	    {
-	      tree folded = fold_build1 (unary_operator,
-					 TREE_TYPE (cast_expression),
-					 cast_expression);
-	      if (CONSTANT_CLASS_P (folded) && !TREE_OVERFLOW (folded))
+	      tree stripped_expr
+		= tree_strip_any_location_wrapper (cast_expression);
+	      if (CONSTANT_CLASS_P (stripped_expr)
+		  && !integer_zerop (stripped_expr)
+		  && !TREE_OVERFLOW (stripped_expr))
 		{
-		  expression = cp_expr (folded, loc);
-		  break;
+		  tree folded = fold_build1 (unary_operator,
+					     TREE_TYPE (stripped_expr),
+					     stripped_expr);
+		  if (CONSTANT_CLASS_P (folded) && !TREE_OVERFLOW (folded))
+		    {
+		      expression = maybe_wrap_with_location (folded, loc);
+		      break;
+		    }
 		}
 	    }
 	  /* Fall through.  */
@@ -8489,6 +8497,8 @@ cp_parser_has_attribute_expression (cp_parser *parser)
   if (!oper || oper == error_mark_node)
     oper = cp_parser_unary_expression (parser);
 
+  STRIP_ANY_LOCATION_WRAPPER (oper);
+
   /* Go back to evaluating expressions.  */
   --cp_unevaluated_operand;
   --c_inhibit_evaluation_warnings;
@@ -9508,7 +9518,7 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p,
 		      || (TREE_CODE (TREE_TYPE (TREE_OPERAND (current.lhs, 0)))
 			  != BOOLEAN_TYPE))))
 	  /* Avoid warning for !!b == y where b is boolean.  */
-	  && (!DECL_P (current.lhs)
+	  && (!DECL_P (tree_strip_any_location_wrapper (current.lhs))
 	      || TREE_TYPE (current.lhs) == NULL_TREE
 	      || TREE_CODE (TREE_TYPE (current.lhs)) != BOOLEAN_TYPE))
 	warn_logical_not_parentheses (current.loc, current.tree_type,
@@ -14546,6 +14556,7 @@ cp_parser_decltype (cp_parser *parser)
       ++c_inhibit_evaluation_warnings;
 
       expr = cp_parser_decltype_expr (parser, id_expression_or_member_access_p);
+      STRIP_ANY_LOCATION_WRAPPER (expr);
 
       /* Go back to evaluating expressions.  */
       --cp_unevaluated_operand;
@@ -14923,7 +14934,9 @@ cp_parser_mem_initializer (cp_parser* parser)
       vec = cp_parser_parenthesized_expression_list (parser, non_attr,
 						     /*cast_p=*/false,
 						     /*allow_expansion_p=*/true,
-						     /*non_constant_p=*/NULL);
+						     /*non_constant_p=*/NULL,
+						     /*close_paren_loc=*/NULL,
+						     /*wrap_locations_p=*/true);
       if (vec == NULL)
 	return error_mark_node;
       expression_list = build_tree_list_vec (vec);
@@ -15464,6 +15477,11 @@ cp_parser_template_parameter_list (cp_parser* parser)
 {
   tree parameter_list = NULL_TREE;
 
+  /* Don't create wrapper nodes within a template-parameter-list,
+     since we don't want to have different types based on the
+     spelling location of constants and decls within them.  */
+  auto_suppress_location_wrappers sentinel;
+
   begin_template_parm_list ();
 
   /* The loop below parses the template parms.  We first need to know
@@ -16636,6 +16654,9 @@ cp_parser_template_argument_list (cp_parser* parser)
   bool saved_ice_p;
   bool saved_non_ice_p;
 
+  /* Don't create location wrapper nodes within a template-argument-list.  */
+  auto_suppress_location_wrappers sentinel;
+
   saved_in_template_argument_list_p = parser->in_template_argument_list_p;
   parser->in_template_argument_list_p = true;
   /* Even if the template-id appears in an integral
@@ -22313,6 +22334,9 @@ cp_parser_parameter_declaration (cp_parser *parser,
   else
     default_argument = NULL_TREE;
 
+  if (default_argument)
+    STRIP_ANY_LOCATION_WRAPPER (default_argument);
+
   /* Generate a location for the parameter, ranging from the start of the
      initial token to the end of the final token (using input_location for
      the latter, set up by cp_lexer_set_source_position_from_token when
@@ -25661,6 +25685,10 @@ cp_parser_gnu_attribute_list (cp_parser* parser, bool exactly_one /* = false */)
   tree attribute_list = NULL_TREE;
   bool save_translate_strings_p = parser->translate_strings_p;
 
+  /* Don't create wrapper nodes within attributes: the
+     handlers don't know how to handle them.  */
+  auto_suppress_location_wrappers sentinel;
+
   parser->translate_strings_p = false;
   while (true)
     {
@@ -26106,6 +26134,10 @@ cp_parser_std_attribute_spec_seq (cp_parser *parser)
   tree attr_specs = NULL_TREE;
   tree attr_last = NULL_TREE;
 
+  /* Don't create wrapper nodes within attributes: the
+     handlers don't know how to handle them.  */
+  auto_suppress_location_wrappers sentinel;
+
   while (true)
     {
       tree attr_spec = cp_parser_std_attribute_spec (parser);
@@ -34880,6 +34912,9 @@ cp_parser_omp_all_clauses (cp_parser *parser, omp_clause_mask mask,
   bool first = true;
   cp_token *token = NULL;
 
+  /* Don't create location wrapper nodes within OpenMP clauses.  */
+  auto_suppress_location_wrappers sentinel;
+
   while (cp_lexer_next_token_is_not (parser->lexer, CPP_PRAGMA_EOL))
     {
       pragma_omp_clause c_kind;
@@ -36597,6 +36632,10 @@ cp_parser_omp_for_loop (cp_parser *parser, enum tree_code code, tree clauses,
 	}
       loc = cp_lexer_consume_token (parser->lexer)->location;
 
+      /* Don't create location wrapper nodes within an OpenMP "for"
+	 statement.  */
+      auto_suppress_location_wrappers sentinel;
+
       matching_parens parens;
       if (!parens.require_open (parser))
 	return NULL;
@@ -39168,6 +39207,8 @@ cp_parser_omp_declare_reduction_exprs (tree fndecl, cp_parser *parser)
       else
 	{
 	  cp_parser_parse_tentatively (parser);
+	  /* Don't create location wrapper nodes here.  */
+	  auto_suppress_location_wrappers sentinel;
 	  tree fn_name = cp_parser_id_expression (parser, /*template_p=*/false,
 						  /*check_dependency_p=*/true,
 						  /*template_p=*/NULL,