[gcc r11-7915] c++: duplicate const static members [PR 99283]

[gcc r11-7915] c++: duplicate const static members [PR 99283]

[Nathan Sidwell]

https://gcc.gnu.org/g:5f3c6027257118469a722816e228394b5978ddb0

commit r11-7915-g5f3c6027257118469a722816e228394b5978ddb0
Author: Nathan Sidwell <nathan@acm.org>
Date:   Tue Mar 30 09:45:59 2021 -0700

    c++: duplicate const static members [PR 99283]
    
    This is the bug that keeps on giving.  Reducing it has been successful
    at hitting other defects. In this case, some more specialization hash
    table fun, plus an issue with reading in a definition of a duplicated
    declaration.  At least I discovered a null context check is no longer
    needed.
    
            PR c++/99283
            gcc/cp/
            * module.cc (dumper::operator): Make less brittle.
            (trees_out::core_bools): VAR_DECLs always have a context.
            (trees_out::key_mergeable): Use same_type_p for asserting.
            (trees_in::read_var_def): Propagate
            DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P.
            gcc/testsuite/
            * g++.dg/modules/pr99283-5.h: New.
            * g++.dg/modules/pr99283-5_a.H: New.
            * g++.dg/modules/pr99283-5_b.H: New.
            * g++.dg/modules/pr99283-5_c.C: New.

Diff:
---
 gcc/cp/module.cc                           | 22 ++++++++++++++--------
 gcc/testsuite/g++.dg/modules/pr99283-5.h   |  9 +++++++++
 gcc/testsuite/g++.dg/modules/pr99283-5_a.H | 14 ++++++++++++++
 gcc/testsuite/g++.dg/modules/pr99283-5_b.H | 12 ++++++++++++
 gcc/testsuite/g++.dg/modules/pr99283-5_c.C |  5 +++++
 5 files changed, 54 insertions(+), 8 deletions(-)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 8a1cfbdfdcb..fab6b573d24 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -4325,8 +4325,8 @@ dumper::operator () (const char *format, ...)
 	case 'N': /* Name.  */
 	  {
 	    tree t = va_arg (args, tree);
-	    if (t && TREE_CODE (t) == OVERLOAD)
-	      t = OVL_FIRST (t);
+	    while (t && TREE_CODE (t) == OVERLOAD)
+	      t = OVL_FUNCTION (t);
 	    fputc ('\'', dumps->stream);
 	    dumps->nested_name (t);
 	    fputc ('\'', dumps->stream);
@@ -5206,8 +5206,7 @@ trees_out::core_bools (tree t)
       else if (code == VAR_DECL)
 	{
 	  /* This is DECL_INITIALIZED_P.  */
-	  if (DECL_CONTEXT (t)
-	      && TREE_CODE (DECL_CONTEXT (t)) != FUNCTION_DECL)
+	  if (TREE_CODE (DECL_CONTEXT (t)) != FUNCTION_DECL)
 	    /* We'll set this when reading the definition.  */
 	    flag_1 = false;
 	}
@@ -10331,8 +10330,8 @@ trees_out::key_mergeable (int tag, merge_kind mk, tree decl, tree inner,
 	      if (mk & MK_tmpl_alias_mask)
 		/* It should be in both tables.  */
 		gcc_checking_assert
-		  (match_mergeable_specialization (false, entry)
-		   == TREE_TYPE (existing));
+		  (same_type_p (match_mergeable_specialization (false, entry),
+				TREE_TYPE (existing)));
 	      if (mk & MK_tmpl_tmpl_mask)
 		existing = DECL_TI_TEMPLATE (existing);
 	    }
@@ -10345,7 +10344,10 @@ trees_out::key_mergeable (int tag, merge_kind mk, tree decl, tree inner,
 	    }
 
 	  /* The walkabout should have found ourselves.  */
-	  gcc_checking_assert (existing == decl);
+	  gcc_checking_assert (TREE_CODE (decl) == TYPE_DECL
+			       ? same_type_p (TREE_TYPE (decl),
+					      TREE_TYPE (existing))
+			       : existing == decl);
 	}
     }
   else if (mk != MK_unique)
@@ -11513,7 +11515,11 @@ trees_in::read_var_def (tree decl, tree maybe_template)
       if (DECL_EXTERNAL (decl))
 	DECL_NOT_REALLY_EXTERN (decl) = true;
       if (VAR_P (decl))
-	DECL_INITIALIZED_P (decl) = true;
+	{
+	  DECL_INITIALIZED_P (decl) = true;
+	  if (maybe_dup && DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (maybe_dup))
+	    DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl) = true;
+	}
       DECL_INITIAL (decl) = init;
       if (!dyn_init)
 	;
diff --git a/gcc/testsuite/g++.dg/modules/pr99283-5.h b/gcc/testsuite/g++.dg/modules/pr99283-5.h
new file mode 100644
index 00000000000..3c3421f2d1c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99283-5.h
@@ -0,0 +1,9 @@
+template<typename _Value>
+struct __traits
+{
+  static const int __digits = 8;
+  static const _Value __min = 0;
+};
+
+template<typename _Value>
+const _Value __traits<_Value>::__min;
diff --git a/gcc/testsuite/g++.dg/modules/pr99283-5_a.H b/gcc/testsuite/g++.dg/modules/pr99283-5_a.H
new file mode 100644
index 00000000000..6406dfe8102
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99283-5_a.H
@@ -0,0 +1,14 @@
+// PR 99283 part 5
+// { dg-additional-options -fmodule-header }
+// { dg-module-cmi {} }
+
+#include "pr99283-5.h"
+
+template<typename _Value>
+const int __traits<_Value>::__digits;
+
+template<typename _Tp>
+void Foo ()
+{
+  __traits<unsigned>::__digits;
+}
diff --git a/gcc/testsuite/g++.dg/modules/pr99283-5_b.H b/gcc/testsuite/g++.dg/modules/pr99283-5_b.H
new file mode 100644
index 00000000000..3f4237e2e4f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99283-5_b.H
@@ -0,0 +1,12 @@
+// { dg-additional-options {-fmodule-header -fno-module-lazy} }
+// { dg-module-cmi {} }
+
+#include "pr99283-5.h"
+
+template<typename _Tp>
+void Bar ()
+{
+  __traits<unsigned>::__min;
+}
+
+import  "pr99283-5_a.H";
diff --git a/gcc/testsuite/g++.dg/modules/pr99283-5_c.C b/gcc/testsuite/g++.dg/modules/pr99283-5_c.C
new file mode 100644
index 00000000000..cc7e795c829
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99283-5_c.C
@@ -0,0 +1,5 @@
+// { dg-additional-options {-fmodules-ts -fno-module-lazy} }
+
+import  "pr99283-5_b.H";
+
+static_assert(!__traits<unsigned>::__min);