Re: [PATCH] c++ modules: verify_type failure with typedef enum [PR106848]

[Patrick Palka <ppalka@redhat.com>]

On Mon, 24 Oct 2022, Nathan Sidwell wrote:

> On 10/21/22 09:11, Patrick Palka wrote:
> > On Fri, 21 Oct 2022, Nathan Sidwell wrote:
> 
> > > 
> > > Thanks for the explanation, it's a situation I didn;t anticipate and your
> > > fix
> > > is good.  Could you add a comment about why you need to propagate the
> > > values
> > > though?
> > 
> > Thanks a lot, will do.  Just to make sure since there are multiple
> > solutions proposed, do you prefer to go with
> > https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603487.html
> > or
> > https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603831.html ?
> > 
> > Both solutions fix the PR106848 issue (empty TYPE_MIN/MAX_VALUE on an
> > enum type variant), but the latter also fixes the related PR102600
> > (empty TYPE_MIN/MAX_VALUE on the main variant of an enum with no
> > enumerators).  (We could maybe even combine the two solutions: stream
> > TYPE_MIN/MAX_VALUE as part of ENUMERAL_TYPE, and also update TYPE_VALUES
> > of each variant during trees_in::read_enum_def)
> 
> 
> Oh, let's go with the latter:
> 
> 	* module.cc (trees_out::core_vals): Stream TYPE_MAX_VALUE and
> 	TYPE_MIN_VALUE of ENUMERAL_TYPE.
> 	(trees_in::core_vals): Likewise.
> 	(trees_out::write_enum_def): Don't stream them here.
> 	(trees_in::read_enum_def): Likewise.
> 
> but, again, some comments -- at the new streaming point, and in the defn
> streamer were we no longer stream them.
> 
> thanks.

Thanks a lot, here's what I ended up committing:

-- >8 --

Subject: [PATCH] c++ modules: enum TYPE_MIN/MAX_VALUE streaming [PR106848]

In the frontend, the TYPE_MIN/MAX_VALUE of ENUMERAL_TYPE is the same as
that of the enum's underlying type (see start_enum).  And the underlying
type of an enum is always known, even for an opaque enum that lacks a
definition.

But currently, we stream TYPE_MIN/MAX_VALUE of an enum only as part of
its definition.  So if the enum is declared but never defined, the
ENUMERAL_TYPE we stream in will have empty TYPE_MIN/MAX_VALUE fields
despite these fields being non-empty on stream out.

And even if the enum is defined, read_enum_def updates these fields only
on the main variant of the enum type, so for other variants (that we may
have streamed in earlier) these fields remain empty.  That these fields
are unexpectedly empty for some ENUMERAL_TYPEs is ultimately the cause
of the below two PRs.

This patch fixes this by making us stream TYPE_MIN/MAX_VALUE directly
for each ENUMERAL_TYPE rather than as part of the enum's definition, so
that we naturally also stream these fields for opaque enums (and each
enum type variant).

	PR c++/106848
	PR c++/102600

gcc/cp/ChangeLog:

	* module.cc (trees_out::core_vals): Stream TYPE_MAX_VALUE and
	TYPE_MIN_VALUE of ENUMERAL_TYPE.
	(trees_in::core_vals): Likewise.
	(trees_out::write_enum_def): Don't stream them here.
	(trees_in::read_enum_def): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/enum-9_a.H: New test.
	* g++.dg/modules/enum-9_b.C: New test.
	* g++.dg/modules/enum-10_a.H: New test.
	* g++.dg/modules/enum-10_b.C: New test.
	* g++.dg/modules/enum-11_a.H: New test.
	* g++.dg/modules/enum-11_b.C: New test.
---
 gcc/cp/module.cc                         | 39 +++++++++++++++---------
 gcc/testsuite/g++.dg/modules/enum-10_a.H |  5 +++
 gcc/testsuite/g++.dg/modules/enum-10_b.C |  6 ++++
 gcc/testsuite/g++.dg/modules/enum-11_a.H |  5 +++
 gcc/testsuite/g++.dg/modules/enum-11_b.C |  8 +++++
 gcc/testsuite/g++.dg/modules/enum-9_a.H  | 13 ++++++++
 gcc/testsuite/g++.dg/modules/enum-9_b.C  |  6 ++++
 7 files changed, 67 insertions(+), 15 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/modules/enum-10_a.H
 create mode 100644 gcc/testsuite/g++.dg/modules/enum-10_b.C
 create mode 100644 gcc/testsuite/g++.dg/modules/enum-11_a.H
 create mode 100644 gcc/testsuite/g++.dg/modules/enum-11_b.C
 create mode 100644 gcc/testsuite/g++.dg/modules/enum-9_a.H
 create mode 100644 gcc/testsuite/g++.dg/modules/enum-9_b.C

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 73971e7ff47..9957df510e6 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -6017,9 +6017,17 @@ trees_out::core_vals (tree t)
 
   if (CODE_CONTAINS_STRUCT (code, TS_TYPE_NON_COMMON))
     {
+      if (code == ENUMERAL_TYPE)
+	{
+	  /* These fields get set even for opaque enums that lack a
+	     definition, so we stream them directly for each ENUMERAL_TYPE.
+	     We stream TYPE_VALUES as part of the definition.  */
+	  WT (t->type_non_common.maxval);
+	  WT (t->type_non_common.minval);
+	}
       /* Records and unions hold FIELDS, VFIELD & BINFO on these
 	 things.  */
-      if (!RECORD_OR_UNION_CODE_P (code) && code != ENUMERAL_TYPE)
+      else if (!RECORD_OR_UNION_CODE_P (code))
 	{
 	  // FIXME: These are from tpl_parm_value's 'type' writing.
 	  // Perhaps it should just be doing them directly?
@@ -6530,9 +6538,17 @@ trees_in::core_vals (tree t)
 
   if (CODE_CONTAINS_STRUCT (code, TS_TYPE_NON_COMMON))
     {
+      if (code == ENUMERAL_TYPE)
+	{
+	  /* These fields get set even for opaque enums that lack a
+	     definition, so we stream them directly for each ENUMERAL_TYPE.
+	     We stream TYPE_VALUES as part of the definition.  */
+	  RT (t->type_non_common.maxval);
+	  RT (t->type_non_common.minval);
+	}
       /* Records and unions hold FIELDS, VFIELD & BINFO on these
 	 things.  */
-      if (!RECORD_OR_UNION_CODE_P (code) && code != ENUMERAL_TYPE)
+      else if (!RECORD_OR_UNION_CODE_P (code))
 	{
 	  /* This is not clobbering TYPE_CACHED_VALUES, because this
 	     is a type that doesn't have any.  */
@@ -12217,8 +12233,8 @@ trees_out::write_enum_def (tree decl)
   tree type = TREE_TYPE (decl);
 
   tree_node (TYPE_VALUES (type));
-  tree_node (TYPE_MIN_VALUE (type));
-  tree_node (TYPE_MAX_VALUE (type));
+  /* Note that we stream TYPE_MIN/MAX_VALUE directly as part of the
+     ENUMERAL_TYPE.  */
 }
 
 void
@@ -12242,8 +12258,6 @@ trees_in::read_enum_def (tree defn, tree maybe_template)
 {
   tree type = TREE_TYPE (defn);
   tree values = tree_node ();
-  tree min = tree_node ();
-  tree max = tree_node ();
 
   if (get_overrun ())
     return false;
@@ -12254,8 +12268,8 @@ trees_in::read_enum_def (tree defn, tree maybe_template)
   if (installing)
     {
       TYPE_VALUES (type) = values;
-      TYPE_MIN_VALUE (type) = min;
-      TYPE_MAX_VALUE (type) = max;
+      /* Note that we stream TYPE_MIN/MAX_VALUE directly as part of the
+	 ENUMERAL_TYPE.  */
 
       rest_of_type_compilation (type, DECL_NAMESPACE_SCOPE_P (defn));
     }
@@ -12269,22 +12283,17 @@ trees_in::read_enum_def (tree defn, tree maybe_template)
 	  tree new_decl = TREE_VALUE (values);
 
 	  if (DECL_NAME (known_decl) != DECL_NAME (new_decl))
-	    goto bad;
+	    break;
 	      
 	  new_decl = maybe_duplicate (new_decl);
 
 	  if (!cp_tree_equal (DECL_INITIAL (known_decl),
 			      DECL_INITIAL (new_decl)))
-	    goto bad;
+	    break;
 	}
 
       if (known || values)
-	goto bad;
-
-      if (!cp_tree_equal (TYPE_MIN_VALUE (type), min)
-	  || !cp_tree_equal (TYPE_MAX_VALUE (type), max))
 	{
-	bad:;
 	  error_at (DECL_SOURCE_LOCATION (maybe_dup),
 		    "definition of %qD does not match", maybe_dup);
 	  inform (DECL_SOURCE_LOCATION (defn),
diff --git a/gcc/testsuite/g++.dg/modules/enum-10_a.H b/gcc/testsuite/g++.dg/modules/enum-10_a.H
new file mode 100644
index 00000000000..fb7d10ad3b6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/enum-10_a.H
@@ -0,0 +1,5 @@
+// PR c++/106848
+// { dg-additional-options -fmodule-header }
+// { dg-module-cmi {} }
+
+typedef enum memory_order { memory_order_seq_cst } memory_order;
diff --git a/gcc/testsuite/g++.dg/modules/enum-10_b.C b/gcc/testsuite/g++.dg/modules/enum-10_b.C
new file mode 100644
index 00000000000..76dc3152963
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/enum-10_b.C
@@ -0,0 +1,6 @@
+// PR c++/106848
+// { dg-additional-options "-fmodules-ts -g" }
+
+import "enum-10_a.H";
+
+memory_order x = memory_order_seq_cst;
diff --git a/gcc/testsuite/g++.dg/modules/enum-11_a.H b/gcc/testsuite/g++.dg/modules/enum-11_a.H
new file mode 100644
index 00000000000..1aecabfd0bd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/enum-11_a.H
@@ -0,0 +1,5 @@
+// PR c++/102600
+// { dg-additional-options -fmodule-header }
+// { dg-module-cmi {} }
+
+enum class byte : unsigned char { };
diff --git a/gcc/testsuite/g++.dg/modules/enum-11_b.C b/gcc/testsuite/g++.dg/modules/enum-11_b.C
new file mode 100644
index 00000000000..4d77cab8953
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/enum-11_b.C
@@ -0,0 +1,8 @@
+// PR c++/102600
+// { dg-additional-options -fmodules-ts }
+
+import "enum-11_a.H";
+
+void push(byte) {}
+void write(char v) { push(static_cast<byte>(v)); }
+int main() { write(char{}); }
diff --git a/gcc/testsuite/g++.dg/modules/enum-9_a.H b/gcc/testsuite/g++.dg/modules/enum-9_a.H
new file mode 100644
index 00000000000..0dd4a0f2fb1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/enum-9_a.H
@@ -0,0 +1,13 @@
+// PR c++/106848
+// { dg-additional-options -fmodule-header }
+// { dg-module-cmi {} }
+
+template<typename _T1>
+struct pair {
+  using type = void(*)(const _T1&);
+};
+
+struct _ScannerBase {
+  enum _TokenT { _S_token_anychar };
+  pair<_TokenT> _M_token_tbl;
+};
diff --git a/gcc/testsuite/g++.dg/modules/enum-9_b.C b/gcc/testsuite/g++.dg/modules/enum-9_b.C
new file mode 100644
index 00000000000..95e2812b81e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/enum-9_b.C
@@ -0,0 +1,6 @@
+// PR c++/106848
+// { dg-additional-options "-fmodules-ts -g" }
+
+import "enum-9_a.H";
+
+_ScannerBase s;
-- 
2.38.1.143.g1fc3c0ad40