[gcc r15-2695] c++: DR882, main cannot be deleted [PR116169]

[Marek Polacek via Gcc-cvs]

https://gcc.gnu.org/g:a790828ccb3b06a7771f871651e7b54d13c3a168

commit r15-2695-ga790828ccb3b06a7771f871651e7b54d13c3a168
Author: Marek Polacek <pola...@redhat.com>
Date:   Thu Aug 1 11:32:26 2024 -0400

    c++: DR882, main cannot be deleted [PR116169]
    
    This DR clarifies that "int main() = delete;" is ill-formed.
    
            PR c++/116169
    
    gcc/cp/ChangeLog:
    
            * decl.cc (cp_finish_decl): Disallow deleting ::main.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/DRs/dr882.C: New test.

Diff:
---
 gcc/cp/decl.cc                   | 26 ++++++++++++++++++--------
 gcc/testsuite/g++.dg/DRs/dr882.C |  5 +++++
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 279af21eed03..687ae6937f53 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -8649,15 +8649,25 @@ cp_finish_decl (tree decl, tree init, bool 
init_const_expr_p,
              && TREE_TYPE (init) == ridpointers[(int)RID_DELETE]))
        {
          /* FIXME check this is 1st decl.  */
-         DECL_DELETED_FN (decl) = 1;
-         DECL_DECLARED_INLINE_P (decl) = 1;
-         DECL_INITIAL (decl)
-           = TREE_CODE (init) == STRING_CST ? init : error_mark_node;
-         FOR_EACH_CLONE (clone, decl)
+         if (UNLIKELY (DECL_MAIN_P (decl)))
            {
-             DECL_DELETED_FN (clone) = 1;
-             DECL_DECLARED_INLINE_P (clone) = 1;
-             DECL_INITIAL (clone) = DECL_INITIAL (decl);
+             /* [basic.start.main]/3: A program that defines main as deleted
+                is ill-formed.  */
+             error ("%<::main%> cannot be deleted");
+             DECL_INITIAL (decl) = NULL_TREE;
+           }
+         else
+           {
+             DECL_DELETED_FN (decl) = 1;
+             DECL_DECLARED_INLINE_P (decl) = 1;
+             DECL_INITIAL (decl)
+               = TREE_CODE (init) == STRING_CST ? init : error_mark_node;
+             FOR_EACH_CLONE (clone, decl)
+               {
+                 DECL_DELETED_FN (clone) = 1;
+                 DECL_DECLARED_INLINE_P (clone) = 1;
+                 DECL_INITIAL (clone) = DECL_INITIAL (decl);
+               }
            }
          init = NULL_TREE;
        }
diff --git a/gcc/testsuite/g++.dg/DRs/dr882.C b/gcc/testsuite/g++.dg/DRs/dr882.C
new file mode 100644
index 000000000000..c41cf7416a29
--- /dev/null
+++ b/gcc/testsuite/g++.dg/DRs/dr882.C
@@ -0,0 +1,5 @@
+// DR882 - Defining main as deleted
+// PR c++/116169
+// { dg-do compile { target c++11 } }
+
+int main() = delete; // { dg-error "cannot be deleted" }