[PATCH] c++/modules: Allow exporting const-qualified namespace-scope variables [PR99232]

[PATCH] c++/modules: Allow exporting const-qualified namespace-scope variables [PR99232]

[Nathaniel Shead]

Bootstrapped and regtested on x86_64-pc-linux-gnu. I don't have write
access.

-- >8 --

By [basic.link] p3.2.1, a non-template non-volatile const-qualified
variable is not necessarily internal linkage in a module declaration,
and rather may have module linkage (or external linkage if it is
exported, see p4.8).

	PR c++/99232

gcc/cp/ChangeLog:

	* decl.cc (grokvardecl): Don't mark variables attached to
        modules as internal.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/pr99232_a.C: New test.
	* g++.dg/modules/pr99232_b.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---
 gcc/cp/decl.cc                           | 3 ++-
 gcc/testsuite/g++.dg/modules/pr99232_a.C | 8 ++++++++
 gcc/testsuite/g++.dg/modules/pr99232_b.C | 7 +++++++
 3 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/modules/pr99232_a.C
 create mode 100644 gcc/testsuite/g++.dg/modules/pr99232_b.C

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index d2ed46b1453..173dd93ef5b 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -10992,7 +10992,8 @@ grokvardecl (tree type,
 			    && (DECL_THIS_EXTERN (decl)
 				|| ! constp
 				|| volatilep
-				|| inlinep));
+				|| inlinep
+				|| module_attach_p ()));
       TREE_STATIC (decl) = ! DECL_EXTERNAL (decl);
     }
   /* Not at top level, only `static' makes a static definition.  */
diff --git a/gcc/testsuite/g++.dg/modules/pr99232_a.C b/gcc/testsuite/g++.dg/modules/pr99232_a.C
new file mode 100644
index 00000000000..33b3b783399
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99232_a.C
@@ -0,0 +1,8 @@
+// PR c++/99232
+// { dg-additional-options "-fmodules-ts" }
+// { dg-module-cmi pr99232 }
+
+export module pr99232;
+
+export const double lambda{ 1.3 };
+export constexpr int a = 42;
diff --git a/gcc/testsuite/g++.dg/modules/pr99232_b.C b/gcc/testsuite/g++.dg/modules/pr99232_b.C
new file mode 100644
index 00000000000..98f3c52a51c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99232_b.C
@@ -0,0 +1,7 @@
+// PR c++/99232
+// { dg-additional-options "-fmodules-ts" }
+
+import pr99232;
+
+double foo() { return lambda * 2.0; }
+static_assert(a == 42);
-- 
2.42.0

Re: [PATCH] c++/modules: Allow exporting const-qualified namespace-scope variables [PR99232]

[Nathan Sidwell]

On 11/15/23 07:24, Nathaniel Shead wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu. I don't have write
> access.
> 
> -- >8 --
> 
> By [basic.link] p3.2.1, a non-template non-volatile const-qualified
> variable is not necessarily internal linkage in a module declaration,
> and rather may have module linkage (or external linkage if it is
> exported, see p4.8).

ok, but can you augment the testcase to check the address is the same in both 
TUs?  (something like an accessor in the module and a runtime-check in the 
importer?)

nathan

> 
> 	PR c++/99232
> 
> gcc/cp/ChangeLog:
> 
> 	* decl.cc (grokvardecl): Don't mark variables attached to
>          modules as internal.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/modules/pr99232_a.C: New test.
> 	* g++.dg/modules/pr99232_b.C: New test.
> 
> Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
> ---
>   gcc/cp/decl.cc                           | 3 ++-
>   gcc/testsuite/g++.dg/modules/pr99232_a.C | 8 ++++++++
>   gcc/testsuite/g++.dg/modules/pr99232_b.C | 7 +++++++
>   3 files changed, 17 insertions(+), 1 deletion(-)
>   create mode 100644 gcc/testsuite/g++.dg/modules/pr99232_a.C
>   create mode 100644 gcc/testsuite/g++.dg/modules/pr99232_b.C
> 
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index d2ed46b1453..173dd93ef5b 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -10992,7 +10992,8 @@ grokvardecl (tree type,
>   			    && (DECL_THIS_EXTERN (decl)
>   				|| ! constp
>   				|| volatilep
> -				|| inlinep));
> +				|| inlinep
> +				|| module_attach_p ()));
>         TREE_STATIC (decl) = ! DECL_EXTERNAL (decl);
>       }
>     /* Not at top level, only `static' makes a static definition.  */
> diff --git a/gcc/testsuite/g++.dg/modules/pr99232_a.C b/gcc/testsuite/g++.dg/modules/pr99232_a.C
> new file mode 100644
> index 00000000000..33b3b783399
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr99232_a.C
> @@ -0,0 +1,8 @@
> +// PR c++/99232
> +// { dg-additional-options "-fmodules-ts" }
> +// { dg-module-cmi pr99232 }
> +
> +export module pr99232;
> +
> +export const double lambda{ 1.3 };
> +export constexpr int a = 42;
> diff --git a/gcc/testsuite/g++.dg/modules/pr99232_b.C b/gcc/testsuite/g++.dg/modules/pr99232_b.C
> new file mode 100644
> index 00000000000..98f3c52a51c
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr99232_b.C
> @@ -0,0 +1,7 @@
> +// PR c++/99232
> +// { dg-additional-options "-fmodules-ts" }
> +
> +import pr99232;
> +
> +double foo() { return lambda * 2.0; }
> +static_assert(a == 42);

-- 
Nathan Sidwell