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* [gcc r13-2744] c++: modules and non-dependent auto deduction
@ 2022-09-20 20:14 Patrick Palka
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From: Patrick Palka @ 2022-09-20 20:14 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:4fac53d652218946b82af4431a801ab1551f0e79
commit r13-2744-g4fac53d652218946b82af4431a801ab1551f0e79
Author: Patrick Palka <ppalka@redhat.com>
Date: Tue Sep 20 16:08:14 2022 -0400
c++: modules and non-dependent auto deduction
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 non-dependent VAR_DECL with deduced 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
tests 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.
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.
Diff:
---
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(+)
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";
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