c++: Diagnose a deduction guide in a wrong scope [PR91759]

The following testcase is accepts-invalid since r7-6608-ga56c0ac08242269b.
Before that change we had this
"deduction guide %qD must be declared in the same scope as %qT"
diagnostics for it, after the change it is expected to be diagnosed
in set_decl_namespace at the not_found: label in there.  On this testcase
nothing is diagnosed though, because set_decl_namespace isn't called at all,
as in_namespace is NULL.

The following patch restores the old warning but does it only in case we
don't call set_decl_namespace.

2020-03-18  Jakub Jelinek  <jakub@redhat.com>

	PR c++/91759
	* decl.c (grokfndecl): Restore old diagnostics about deduction
	guide declared in different scope if in_namespace is NULL_TREE.

	* g++.dg/cpp1z/class-deduction72.C: New test.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 1db1e090e51a004365f79cffdea0e552ce006249..9aaa81a17bb24e0ba0abdca8e251713f48fd5b9c 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-03-18  Jakub Jelinek  <jakub@redhat.com>
+
+       PR c++/91759
+       * decl.c (grokfndecl): Restore old diagnostics about deduction
+       guide declared in different scope if in_namespace is NULL_TREE.
+
 2020-03-17  Jakub Jelinek  <jakub@redhat.com>
 
        PR c++/90995

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index d240436d84ac948d50fb61885ff14db14742e1db..319b7ee5c1c4766984086efc9f449da774b62df6 100644 (file)
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -9644,6 +9644,15 @@ grokfndecl (tree ctype,
                    "namespace scope", decl);
          return NULL_TREE;
        }
+      tree type = TREE_TYPE (DECL_NAME (decl));
+      if (in_namespace == NULL_TREE
+         && CP_DECL_CONTEXT (decl) != CP_TYPE_CONTEXT (type))
+       {
+         error_at (location, "deduction guide %qD must be declared in the "
+                             "same scope as %qT", decl, type);
+         inform (location_of (type), "  declared here");
+         return NULL_TREE;
+       }
       if (funcdef_flag)
        error_at (location,
                  "deduction guide %qD must not have a function body", decl);

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 775837d840fa774a27b23571fb25cb467706e9a2..8efb773437be323b4fea4c55dccfcceb139c7cf7 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-18  Jakub Jelinek  <jakub@redhat.com>
+
+       PR c++/91759
+       * g++.dg/cpp1z/class-deduction72.C: New test.
+
 2020-03-17  Uroš Bizjak  <ubizjak@gmail.com>
 
        * g++.dg/debug/dwarf2/const2b.C (dg-do): Fix target selector.

diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction72.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction72.C
new file mode 100644 (file)
index 0000000..60c5599
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction72.C
@@ -0,0 +1,11 @@
+// PR c++/91759
+// { dg-do compile { target c++17 } }
+
+namespace N {
+  template <typename T>
+  struct X{ X(int); }; // { dg-message "declared here" }
+}
+
+using N::X;
+
+X(int) -> X<int>;      // { dg-error "must be declared in the same scope as" }