Re: [PATCH] c++: Check module attachment instead of purview when necessary [PR112631]

[Nathan Sidwell]

On 11/20/23 04:47, Nathaniel Shead wrote:
Bootstrapped and regtested on x86_64-pc-linux-gnu. I don't have write
access.
-- >8 --

Block-scope declarations of functions or extern values are not allowed
when attached to a named module. Similarly, class member functions are
not inline if attached to a named module. However, in both these cases
we currently only check if the declaration is within the module purview;
it is possible for such a declaration to occur within the module purview
but not be attached to a named module (e.g. in an 'extern "C++"' block).
This patch makes the required adjustments.


Ah I'd been puzzling over the default inlinedness of  member-fns of block-scope 
structs.  Could you augment the testcase to make sure that's right too?

Something like:

// dg-module-do link
export module Mod;

export auto Get () {
  struct X { void Fn () {} };
  return X();
}


///
import Mod
void Frob () { Get().Fn(); }


        PR c++/112631

gcc/cp/ChangeLog:

        * cp-tree.h (named_module_attach_p): New function.
        * decl.cc (start_decl): Use named_module_attach_p instead of
        named_module_purview_p.
        (grokmethod): Likewise.

gcc/testsuite/ChangeLog:

        * g++.dg/modules/pr112631.C: New test.
---
  gcc/cp/cp-tree.h                        |  2 ++
  gcc/cp/decl.cc                          | 10 +++++-----
  gcc/testsuite/g++.dg/modules/pr112631.C |  8 ++++++++
  3 files changed, 15 insertions(+), 5 deletions(-)
  create mode 100644 gcc/testsuite/g++.dg/modules/pr112631.C

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 7b0b7c6a17e..9a3981cef58 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7315,6 +7315,8 @@ inline bool module_attach_p ()
  
  inline bool named_module_purview_p ()
  { return named_module_p () && module_purview_p (); }
+inline bool named_module_attach_p ()
+{ return named_module_p () && module_attach_p (); }
  
  /* We're currently exporting declarations.  */
  inline bool module_exporting_p ()
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index e6f75d771e0..395f108aec7 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -5917,10 +5917,10 @@ start_decl (const cp_declarator *declarator,
      {
        /* A function-scope decl of some namespace-scope decl.  */
        DECL_LOCAL_DECL_P (decl) = true;
-      if (named_module_purview_p ())
+      if (named_module_attach_p ())
        error_at (declarator->id_loc,
-                 "block-scope extern declaration %q#D not permitted"
-                 " in module purview", decl);
+                 "block-scope extern declaration %q#D must not be"
+                 " attached to a named module", decl);
      }
  
    /* Enter this declaration into the symbol table.  Don't push the plain
@@ -18513,10 +18513,10 @@ grokmethod (cp_decl_specifier_seq *declspecs,
    check_template_shadow (fndecl);
  
    /* p1779 ABI-Isolation makes inline not a default for in-class
-     definitions in named module purview.  If the user explicitly
+     definitions attached to a named module.  If the user explicitly
       made it inline, grokdeclarator will already have done the right
       things.  */
-  if ((!named_module_purview_p ()
+  if ((!named_module_attach_p ()
         || flag_module_implicit_inline
        /* Lambda's operator function remains inline.  */
         || LAMBDA_TYPE_P (DECL_CONTEXT (fndecl)))
diff --git a/gcc/testsuite/g++.dg/modules/pr112631.C 
b/gcc/testsuite/g++.dg/modules/pr112631.C
new file mode 100644
index 00000000000..b5e81a1041b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr112631.C
@@ -0,0 +1,8 @@
+// { dg-additional-options "-fmodules-ts" }
+// { dg-module-cmi bla }
+
+export module bla;
+
+extern "C++" inline void fun() {
+  void oops();  // { dg-bogus "block-scope extern declaration" }
+}

--
Nathan Sidwell