[PR87768] reset location wrapper suppression when reentering top level

Concepts-checking and other kinds of early tsubsting may often take
place while location wrappers are suppressed, e.g. because we've
triggered template instantiation within template parameter lists.

With that, exprs that are usually wrapped by VIEW_CONVERT_EXPRs
location wrappers may end up wrapped by NON_LVALUE_EXPRs that are not
marked as location wrappers.  If such NON_LVALUE_EXPRs tsubsted exprs
undergo another round of tsubsting, say for constraint checking, or
even for another round of specialization, they will be rejected by
tsubst_copy_and_build.

This patch arranges for suppress_location_wrappers to be saved and
reset when pushing to the top level, and restored when popping from
it.

for  gcc/cp/ChangeLog

	PR c++/87768
	* cp-tree.h (saved_scope): Add suppress_location_wrappers.
	* name-lookup.c (do_push_to_top_level): Save and reset it.
	(do_pop_from_top_level): Restore it.

for  gcc/testsuite/ChangeLog

	PR c++/87768
	* g++.dg/concepts/pr87768.C: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@268006 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 73f1b76e5ff4dfb1be2cf3ecaf7dd240b04a9830..524fbd366c030b769cec1baebad2c7fb034beb4e 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,10 @@
 2019-01-17  Alexandre Oliva <aoliva@redhat.com>
 
+       PR c++/87768
+       * cp-tree.h (saved_scope): Add suppress_location_wrappers.
+       * name-lookup.c (do_push_to_top_level): Save and reset it.
+       (do_pop_from_top_level): Restore it.
+
        PR c++/86648
        * pt.c (make_template_placeholder): Use auto_identifier.
        (is_auto): Drop CLASS_PLACEHOLDER_TEMPLATE test.

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 1c85b37ba7fb33a6a28b5458a545b2c4c91423e1..5cc8f88d52228ae57f0b7fe8f6e5f1d08f52bf6a 100644 (file)
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -1626,6 +1626,7 @@ struct GTY(()) saved_scope {
 
   int x_processing_template_decl;
   int x_processing_specialization;
+  int suppress_location_wrappers;
   BOOL_BITFIELD x_processing_explicit_instantiation : 1;
   BOOL_BITFIELD need_pop_function_context : 1;
 

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index b65fd5f463a1e7f501c86861201690bc3f402cbe..d7b9029b0a3a5c33609713c51dac7977f303db59 100644 (file)
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -7133,6 +7133,7 @@ do_push_to_top_level (void)
   s->function_decl = current_function_decl;
   s->unevaluated_operand = cp_unevaluated_operand;
   s->inhibit_evaluation_warnings = c_inhibit_evaluation_warnings;
+  s->suppress_location_wrappers = suppress_location_wrappers;
   s->x_stmt_tree.stmts_are_full_exprs_p = true;
 
   scope_chain = s;
@@ -7143,6 +7144,7 @@ do_push_to_top_level (void)
   push_class_stack ();
   cp_unevaluated_operand = 0;
   c_inhibit_evaluation_warnings = 0;
+  suppress_location_wrappers = 0;
 }
 
 static void
@@ -7175,6 +7177,7 @@ do_pop_from_top_level (void)
   current_function_decl = s->function_decl;
   cp_unevaluated_operand = s->unevaluated_operand;
   c_inhibit_evaluation_warnings = s->inhibit_evaluation_warnings;
+  suppress_location_wrappers = s->suppress_location_wrappers;
 
   /* Make this saved_scope structure available for reuse by
      push_to_top_level.  */

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3ce3da7940db0c68952aca55d82344a9c33959c5..15cdb1ed432060bb46a7b4c932689c33b7afcbc1 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2019-01-17  Alexandre Oliva <aoliva@redhat.com>
 
+       PR c++/87768
+       * g++.dg/concepts/pr87768.C: New.
+
        PR c++/86648
        * gcc.dg/cpp1z/pr86648.C: New.
 

diff --git a/gcc/testsuite/g++.dg/concepts/pr87768.C b/gcc/testsuite/g++.dg/concepts/pr87768.C
new file mode 100644 (file)
index 0000000..de436e5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/pr87768.C
@@ -0,0 +1,14 @@
+// { dg-do compile { target c++17 } }
+// { dg-options "-fconcepts" }
+
+struct a {};
+template <bool> using b = a;
+
+template <typename> struct c;
+template <typename d>
+  requires requires(d e) { e[0]; }
+struct c<d> {
+  static constexpr bool f = [] { return false; }();
+};
+
+struct g : b<c<unsigned[]>::f> {};