[1/2] c++: modules and non-dependent auto deduction
Commit Message
The modules streaming code seems to rely on the invariant that a
TEMPLATE_DECL and its DECL_TEMPLATE_RESULT have the same TREE_TYPE.
But for a templated VAR_DECL with deduced non-dependent type, the two
TREE_TYPEs end up diverging: cp_finish_decl deduces the type of the
initializer ahead of time and updates the TREE_TYPE of the VAR_DECL, but
neglects to update the corresponding TEMPLATE_DECL as well, which leads
to a "conflicting global module declaration" error for each of the
__phase_alignment decls in the below testcase (and for the xtreme-header
testcases if we try including <barrier>).
This patch makes cp_finish_decl update the TREE_TYPE of the corresponding
TEMPLATE_DECL so that the invariant is maintained.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?
gcc/cp/ChangeLog:
* decl.cc (cp_finish_decl): After updating the deduced type of a
VAR_DECL, also update the corresponding TEMPLATE_DECL if there
is one.
gcc/testsuite/ChangeLog:
* g++.dg/modules/auto-3.h: New test.
* g++.dg/modules/auto-3_a.H: New test.
* g++.dg/modules/auto-3_b.C: New test.
---
gcc/cp/decl.cc | 6 ++++++
gcc/testsuite/g++.dg/modules/auto-3.h | 10 ++++++++++
gcc/testsuite/g++.dg/modules/auto-3_a.H | 4 ++++
gcc/testsuite/g++.dg/modules/auto-3_b.C | 4 ++++
4 files changed, 24 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/modules/auto-3.h
create mode 100644 gcc/testsuite/g++.dg/modules/auto-3_a.H
create mode 100644 gcc/testsuite/g++.dg/modules/auto-3_b.C
Comments
On 9/20/22 15:54, Patrick Palka wrote:
> The modules streaming code seems to rely on the invariant that a
> TEMPLATE_DECL and its DECL_TEMPLATE_RESULT have the same TREE_TYPE.
It does indeed.
> But for a templated VAR_DECL with deduced non-dependent type, the two
> TREE_TYPEs end up diverging: cp_finish_decl deduces the type of the
> initializer ahead of time and updates the TREE_TYPE of the VAR_DECL, but
> neglects to update the corresponding TEMPLATE_DECL as well, which leads
> to a "conflicting global module declaration" error for each of the
> __phase_alignment decls in the below testcase (and for the xtreme-header
> testcases if we try including <barrier>).
>
> This patch makes cp_finish_decl update the TREE_TYPE of the corresponding
> TEMPLATE_DECL so that the invariant is maintained >
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?
Ok, thanks
>
> gcc/cp/ChangeLog:
>
> * decl.cc (cp_finish_decl): After updating the deduced type of a
> VAR_DECL, also update the corresponding TEMPLATE_DECL if there
> is one.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/modules/auto-3.h: New test.
> * g++.dg/modules/auto-3_a.H: New test.
> * g++.dg/modules/auto-3_b.C: New test.
> ---
> gcc/cp/decl.cc | 6 ++++++
> gcc/testsuite/g++.dg/modules/auto-3.h | 10 ++++++++++
> gcc/testsuite/g++.dg/modules/auto-3_a.H | 4 ++++
> gcc/testsuite/g++.dg/modules/auto-3_b.C | 4 ++++
> 4 files changed, 24 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/modules/auto-3.h
> create mode 100644 gcc/testsuite/g++.dg/modules/auto-3_a.H
> create mode 100644 gcc/testsuite/g++.dg/modules/auto-3_b.C
>
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index 070f673c3a2..80467c19254 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -8180,6 +8180,12 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
> return;
> }
> cp_apply_type_quals_to_decl (cp_type_quals (type), decl);
> +
> + /* Update the type of the corresponding TEMPLATE_DECL to match. */
> + if (DECL_LANG_SPECIFIC (decl)
> + && DECL_TEMPLATE_INFO (decl)
> + && DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (decl)) == decl)
> + TREE_TYPE (DECL_TI_TEMPLATE (decl)) = type;
> }
>
> if (ensure_literal_type_for_constexpr_object (decl) == error_mark_node)
> diff --git a/gcc/testsuite/g++.dg/modules/auto-3.h b/gcc/testsuite/g++.dg/modules/auto-3.h
> new file mode 100644
> index 00000000000..f129433cbcb
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/auto-3.h
> @@ -0,0 +1,10 @@
> +template<class>
> +struct __tree_barrier {
> + static const auto __phase_alignment_1 = 0;
> +
> + template<class>
> + static const auto __phase_alignment_2 = 0;
> +};
> +
> +template<class>
> +inline auto __phase_alignment_3 = 0;
> diff --git a/gcc/testsuite/g++.dg/modules/auto-3_a.H b/gcc/testsuite/g++.dg/modules/auto-3_a.H
> new file mode 100644
> index 00000000000..25a7a73e73e
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/auto-3_a.H
> @@ -0,0 +1,4 @@
> +// { dg-additional-options "-fmodule-header" }
> +// { dg-module-cmi {} }
> +
> +#include "auto-3.h"
> diff --git a/gcc/testsuite/g++.dg/modules/auto-3_b.C b/gcc/testsuite/g++.dg/modules/auto-3_b.C
> new file mode 100644
> index 00000000000..03b6d46f476
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/auto-3_b.C
> @@ -0,0 +1,4 @@
> +// { dg-additional-options "-fmodules-ts -fno-module-lazy" }
> +
> +#include "auto-3.h"
> +import "auto-3_a.H";
@@ -8180,6 +8180,12 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
return;
}
cp_apply_type_quals_to_decl (cp_type_quals (type), decl);
+
+ /* Update the type of the corresponding TEMPLATE_DECL to match. */
+ if (DECL_LANG_SPECIFIC (decl)
+ && DECL_TEMPLATE_INFO (decl)
+ && DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (decl)) == decl)
+ TREE_TYPE (DECL_TI_TEMPLATE (decl)) = type;
}
if (ensure_literal_type_for_constexpr_object (decl) == error_mark_node)
new file mode 100644
@@ -0,0 +1,10 @@
+template<class>
+struct __tree_barrier {
+ static const auto __phase_alignment_1 = 0;
+
+ template<class>
+ static const auto __phase_alignment_2 = 0;
+};
+
+template<class>
+inline auto __phase_alignment_3 = 0;
new file mode 100644
@@ -0,0 +1,4 @@
+// { dg-additional-options "-fmodule-header" }
+// { dg-module-cmi {} }
+
+#include "auto-3.h"
new file mode 100644
@@ -0,0 +1,4 @@
+// { dg-additional-options "-fmodules-ts -fno-module-lazy" }
+
+#include "auto-3.h"
+import "auto-3_a.H";