[gcc r15-6750] c++: be permissive about eh spec mismatch for op new

[Jason Merrill via Gcc-cvs]

https://gcc.gnu.org/g:3cae3a80695e5aabd7353c02e179c997158eef30

commit r15-6750-g3cae3a80695e5aabd7353c02e179c997158eef30
Author: Jason Merrill <ja...@redhat.com>
Date:   Thu Jan 9 15:12:07 2025 -0500

    c++: be permissive about eh spec mismatch for op new
    
    r15-3532 made us more strict about exception-specification mismatches with
    the standard library, but let's still be permissive about operator new,
    since previously you needed to say throw(std::bad_alloc).
    
    gcc/cp/ChangeLog:
    
            * decl.cc (check_redeclaration_exception_specification): Be more
            lenient about ::operator new.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/noexcept88.C: New test.

Diff:
---
 gcc/cp/decl.cc                          | 11 +++++++++--
 gcc/testsuite/g++.dg/cpp0x/noexcept88.C |  9 +++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 288da65fd8db..5c6a4996a89e 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -1398,7 +1398,14 @@ check_redeclaration_exception_specification (tree 
new_decl,
       location_t new_loc = DECL_SOURCE_LOCATION (new_decl);
       auto_diagnostic_group d;
 
-      if (DECL_IN_SYSTEM_HEADER (old_decl) && DECL_EXTERN_C_P (old_decl))
+      /* Be permissive about C++98 vs C++11 operator new declarations.  */
+      bool global_new = (IDENTIFIER_NEW_OP_P (DECL_NAME (new_decl))
+                        && CP_DECL_CONTEXT (new_decl) == global_namespace
+                        && (nothrow_spec_p (new_exceptions)
+                            == nothrow_spec_p (old_exceptions)));
+
+      if (DECL_IN_SYSTEM_HEADER (old_decl)
+         && (global_new || DECL_EXTERN_C_P (old_decl)))
        /* Don't fuss about the C library; the C library functions are not
           specified to have exception specifications (just behave as if they
           have them), but some implementations include them.  */
@@ -1407,7 +1414,7 @@ check_redeclaration_exception_specification (tree 
new_decl,
        /* We used to silently permit mismatched eh specs with
           -fno-exceptions, so only complain if -pedantic.  */
        complained = pedwarn (new_loc, OPT_Wpedantic, msg, new_decl);
-      else if (!new_exceptions)
+      else if (!new_exceptions || global_new)
        /* Reduce to pedwarn for omitted exception specification.  No warning
           flag for this; silence the warning by correcting the code.  */
        complained = pedwarn (new_loc, 0, msg, new_decl);
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept88.C 
b/gcc/testsuite/g++.dg/cpp0x/noexcept88.C
new file mode 100644
index 000000000000..9b57fddbf0a9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept88.C
@@ -0,0 +1,9 @@
+// { dg-options -Wsystem-headers }
+
+#include <cstdlib>
+#include <new>
+
+void *operator new (std::size_t) throw (std::bad_alloc); // { dg-line decl }
+// { dg-error "dynamic exception spec" "" { target c++17 } decl }
+// { dg-warning "dynamic exception spec" "" { target { c++11 && { ! c++17 } } 
} decl }
+// { dg-warning "different exception spec" "" { target { c++11 && { ! c++17 } 
} } decl }