diff mbox series

c++/modules: anon union member of as-base class [PR112580]

Message ID 20240201171833.3240525-1-ppalka@redhat.com
State New
Headers show
Series c++/modules: anon union member of as-base class [PR112580] | expand

Commit Message

Patrick Palka Feb. 1, 2024, 5:18 p.m. UTC 
Tested on x86_64-pc-linux-gnu, does this look OK for trunk?

-- >8 --

Here when streaming in the fields of the as-base version of
_Formatting_scanner<int> we end up clobbering ANON_AGGR_TYPE_FIELD
of the anonymous union type, since it turns out this type is shared
between the original FIELD_DECL and the as-base FIELD_DECL copy (copied
during layout_class_type).  ANON_AGGR_TYPE_FIELD first gets properly set
to the original FIELD_DECL when streaming in the canonical definition of
_Formatting_scanner<int>, and then gets overwritten to the as-base
FIELD_DECL when streaming in the the as-base definition.  This leads to
lookup_anon_field giving the wrong answer when resolving the _M_values
use.

This patch makes us avoid overwriting ANON_AGGR_TYPE_FIELD when streaming
in an as-base class definition, it should already be properly set at that
point.

	PR c++/112580

gcc/cp/ChangeLog:

	* module.cc (trees_in::read_class_def): When streaming in
	an anonymous union field of an as-base class, don't clobber
	ANON_AGGR_TYPE_FIELD.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/anon-3_a.H: New test.
	* g++.dg/modules/anon-3_b.C: New test.
---
 gcc/cp/module.cc                        | 12 ++++++++++--
 gcc/testsuite/g++.dg/modules/anon-3_a.H | 21 +++++++++++++++++++++
 gcc/testsuite/g++.dg/modules/anon-3_b.C |  8 ++++++++
 3 files changed, 39 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/modules/anon-3_a.H
 create mode 100644 gcc/testsuite/g++.dg/modules/anon-3_b.C

Comments

Patrick Palka Feb. 8, 2024, 1:58 p.m. UTC | #1 
On Thu, 1 Feb 2024, Patrick Palka wrote:

> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?

Ping.  FWIW this fixes the remaining reported xtreme-header FAILs on
x86_64-linux with -mx32 (not totally sure why the fails don't happen
without -mx32).

> 
> -- >8 --
> 
> Here when streaming in the fields of the as-base version of
> _Formatting_scanner<int> we end up clobbering ANON_AGGR_TYPE_FIELD
> of the anonymous union type, since it turns out this type is shared
> between the original FIELD_DECL and the as-base FIELD_DECL copy (copied
> during layout_class_type).  ANON_AGGR_TYPE_FIELD first gets properly set
> to the original FIELD_DECL when streaming in the canonical definition of
> _Formatting_scanner<int>, and then gets overwritten to the as-base
> FIELD_DECL when streaming in the the as-base definition.  This leads to
> lookup_anon_field giving the wrong answer when resolving the _M_values
> use.
> 
> This patch makes us avoid overwriting ANON_AGGR_TYPE_FIELD when streaming
> in an as-base class definition, it should already be properly set at that
> point.
> 
> 	PR c++/112580
> 
> gcc/cp/ChangeLog:
> 
> 	* module.cc (trees_in::read_class_def): When streaming in
> 	an anonymous union field of an as-base class, don't clobber
> 	ANON_AGGR_TYPE_FIELD.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/modules/anon-3_a.H: New test.
> 	* g++.dg/modules/anon-3_b.C: New test.
> ---
>  gcc/cp/module.cc                        | 12 ++++++++++--
>  gcc/testsuite/g++.dg/modules/anon-3_a.H | 21 +++++++++++++++++++++
>  gcc/testsuite/g++.dg/modules/anon-3_b.C |  8 ++++++++
>  3 files changed, 39 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/g++.dg/modules/anon-3_a.H
>  create mode 100644 gcc/testsuite/g++.dg/modules/anon-3_b.C
> 
> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
> index 3c2fef0e3f4..d36ba2eeeb3 100644
> --- a/gcc/cp/module.cc
> +++ b/gcc/cp/module.cc
> @@ -12178,8 +12178,16 @@ trees_in::read_class_def (tree defn, tree maybe_template)
>  
>  	      if (TREE_CODE (decl) == FIELD_DECL
>  		  && ANON_AGGR_TYPE_P (TREE_TYPE (decl)))
> -		ANON_AGGR_TYPE_FIELD
> -		  (TYPE_MAIN_VARIANT (TREE_TYPE (decl))) = decl;
> +		{
> +		  tree anon_type = TYPE_MAIN_VARIANT (TREE_TYPE (decl));
> +		  if (DECL_NAME (defn) == as_base_identifier)
> +		    /* ANON_AGGR_TYPE_FIELD should already point to the
> +		       original FIELD_DECL, don't overwrite it to point
> +		       to the as-base FIELD_DECL copy.  */
> +		    gcc_checking_assert (ANON_AGGR_TYPE_FIELD (anon_type));
> +		  else
> +		    ANON_AGGR_TYPE_FIELD (anon_type) = decl;
> +		}
>  
>  	      if (TREE_CODE (decl) == USING_DECL
>  		  && TREE_CODE (USING_DECL_SCOPE (decl)) == RECORD_TYPE)
> diff --git a/gcc/testsuite/g++.dg/modules/anon-3_a.H b/gcc/testsuite/g++.dg/modules/anon-3_a.H
> new file mode 100644
> index 00000000000..64a6aab51dd
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/anon-3_a.H
> @@ -0,0 +1,21 @@
> +// PR c++/112580
> +// { dg-additional-options "-fmodule-header" }
> +// { dg-module-cmi {} }
> +
> +template <typename _Out>
> +struct _Formatting_scanner {
> +  union {
> +    int _M_values = 42;
> +  };
> +  virtual int _M_format_arg() { return _M_values; }
> +};
> +
> +template <typename _Tp>
> +auto __do_vformat_to() {
> +  _Formatting_scanner<int> s;
> +  return s;
> +}
> +
> +inline auto vformat() {
> +  return __do_vformat_to<int>();
> +}
> diff --git a/gcc/testsuite/g++.dg/modules/anon-3_b.C b/gcc/testsuite/g++.dg/modules/anon-3_b.C
> new file mode 100644
> index 00000000000..d676fe47536
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/anon-3_b.C
> @@ -0,0 +1,8 @@
> +// PR c++/112580
> +// { dg-additional-options "-fmodules-ts" }
> +
> +import "anon-3_a.H";
> +
> +int main() {
> +  vformat()._M_format_arg();
> +}
> -- 
> 2.43.0.493.gbc7ee2e5e1
> 
>
Jason Merrill Feb. 9, 2024, 4:49 p.m. UTC | #2 
On 2/1/24 12:18, Patrick Palka wrote:
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?

OK.

> -- >8 --
> 
> Here when streaming in the fields of the as-base version of
> _Formatting_scanner<int> we end up clobbering ANON_AGGR_TYPE_FIELD
> of the anonymous union type, since it turns out this type is shared
> between the original FIELD_DECL and the as-base FIELD_DECL copy (copied
> during layout_class_type).  ANON_AGGR_TYPE_FIELD first gets properly set
> to the original FIELD_DECL when streaming in the canonical definition of
> _Formatting_scanner<int>, and then gets overwritten to the as-base
> FIELD_DECL when streaming in the the as-base definition.  This leads to
> lookup_anon_field giving the wrong answer when resolving the _M_values
> use.
> 
> This patch makes us avoid overwriting ANON_AGGR_TYPE_FIELD when streaming
> in an as-base class definition, it should already be properly set at that
> point.
> 
> 	PR c++/112580
> 
> gcc/cp/ChangeLog:
> 
> 	* module.cc (trees_in::read_class_def): When streaming in
> 	an anonymous union field of an as-base class, don't clobber
> 	ANON_AGGR_TYPE_FIELD.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/modules/anon-3_a.H: New test.
> 	* g++.dg/modules/anon-3_b.C: New test.
> ---
>   gcc/cp/module.cc                        | 12 ++++++++++--
>   gcc/testsuite/g++.dg/modules/anon-3_a.H | 21 +++++++++++++++++++++
>   gcc/testsuite/g++.dg/modules/anon-3_b.C |  8 ++++++++
>   3 files changed, 39 insertions(+), 2 deletions(-)
>   create mode 100644 gcc/testsuite/g++.dg/modules/anon-3_a.H
>   create mode 100644 gcc/testsuite/g++.dg/modules/anon-3_b.C
> 
> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
> index 3c2fef0e3f4..d36ba2eeeb3 100644
> --- a/gcc/cp/module.cc
> +++ b/gcc/cp/module.cc
> @@ -12178,8 +12178,16 @@ trees_in::read_class_def (tree defn, tree maybe_template)
>   
>   	      if (TREE_CODE (decl) == FIELD_DECL
>   		  && ANON_AGGR_TYPE_P (TREE_TYPE (decl)))
> -		ANON_AGGR_TYPE_FIELD
> -		  (TYPE_MAIN_VARIANT (TREE_TYPE (decl))) = decl;
> +		{
> +		  tree anon_type = TYPE_MAIN_VARIANT (TREE_TYPE (decl));
> +		  if (DECL_NAME (defn) == as_base_identifier)
> +		    /* ANON_AGGR_TYPE_FIELD should already point to the
> +		       original FIELD_DECL, don't overwrite it to point
> +		       to the as-base FIELD_DECL copy.  */
> +		    gcc_checking_assert (ANON_AGGR_TYPE_FIELD (anon_type));
> +		  else
> +		    ANON_AGGR_TYPE_FIELD (anon_type) = decl;
> +		}
>   
>   	      if (TREE_CODE (decl) == USING_DECL
>   		  && TREE_CODE (USING_DECL_SCOPE (decl)) == RECORD_TYPE)
> diff --git a/gcc/testsuite/g++.dg/modules/anon-3_a.H b/gcc/testsuite/g++.dg/modules/anon-3_a.H
> new file mode 100644
> index 00000000000..64a6aab51dd
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/anon-3_a.H
> @@ -0,0 +1,21 @@
> +// PR c++/112580
> +// { dg-additional-options "-fmodule-header" }
> +// { dg-module-cmi {} }
> +
> +template <typename _Out>
> +struct _Formatting_scanner {
> +  union {
> +    int _M_values = 42;
> +  };
> +  virtual int _M_format_arg() { return _M_values; }
> +};
> +
> +template <typename _Tp>
> +auto __do_vformat_to() {
> +  _Formatting_scanner<int> s;
> +  return s;
> +}
> +
> +inline auto vformat() {
> +  return __do_vformat_to<int>();
> +}
> diff --git a/gcc/testsuite/g++.dg/modules/anon-3_b.C b/gcc/testsuite/g++.dg/modules/anon-3_b.C
> new file mode 100644
> index 00000000000..d676fe47536
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/anon-3_b.C
> @@ -0,0 +1,8 @@
> +// PR c++/112580
> +// { dg-additional-options "-fmodules-ts" }
> +
> +import "anon-3_a.H";
> +
> +int main() {
> +  vformat()._M_format_arg();
> +}
diff mbox series

Patch

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 3c2fef0e3f4..d36ba2eeeb3 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -12178,8 +12178,16 @@  trees_in::read_class_def (tree defn, tree maybe_template)
 
 	      if (TREE_CODE (decl) == FIELD_DECL
 		  && ANON_AGGR_TYPE_P (TREE_TYPE (decl)))
-		ANON_AGGR_TYPE_FIELD
-		  (TYPE_MAIN_VARIANT (TREE_TYPE (decl))) = decl;
+		{
+		  tree anon_type = TYPE_MAIN_VARIANT (TREE_TYPE (decl));
+		  if (DECL_NAME (defn) == as_base_identifier)
+		    /* ANON_AGGR_TYPE_FIELD should already point to the
+		       original FIELD_DECL, don't overwrite it to point
+		       to the as-base FIELD_DECL copy.  */
+		    gcc_checking_assert (ANON_AGGR_TYPE_FIELD (anon_type));
+		  else
+		    ANON_AGGR_TYPE_FIELD (anon_type) = decl;
+		}
 
 	      if (TREE_CODE (decl) == USING_DECL
 		  && TREE_CODE (USING_DECL_SCOPE (decl)) == RECORD_TYPE)
diff --git a/gcc/testsuite/g++.dg/modules/anon-3_a.H b/gcc/testsuite/g++.dg/modules/anon-3_a.H
new file mode 100644
index 00000000000..64a6aab51dd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/anon-3_a.H
@@ -0,0 +1,21 @@ 
+// PR c++/112580
+// { dg-additional-options "-fmodule-header" }
+// { dg-module-cmi {} }
+
+template <typename _Out>
+struct _Formatting_scanner {
+  union {
+    int _M_values = 42;
+  };
+  virtual int _M_format_arg() { return _M_values; }
+};
+
+template <typename _Tp>
+auto __do_vformat_to() {
+  _Formatting_scanner<int> s;
+  return s;
+}
+
+inline auto vformat() {
+  return __do_vformat_to<int>();
+}
diff --git a/gcc/testsuite/g++.dg/modules/anon-3_b.C b/gcc/testsuite/g++.dg/modules/anon-3_b.C
new file mode 100644
index 00000000000..d676fe47536
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/anon-3_b.C
@@ -0,0 +1,8 @@ 
+// PR c++/112580
+// { dg-additional-options "-fmodules-ts" }
+
+import "anon-3_a.H";
+
+int main() {
+  vformat()._M_format_arg();
+}