[gcc/devel/c++-modules] Compare TREE_ADDRESSABLE and TYPE_MODE when ODR checking types.

[Nathan Sidwell]

https://gcc.gnu.org/g:288c5324bf6e418dd94d718d1619464a4f68ff8e

commit 288c5324bf6e418dd94d718d1619464a4f68ff8e
Author: Jan Hubicka <jh@suse.cz>
Date:   Tue Jan 14 21:45:03 2020 +0100

    Compare TREE_ADDRESSABLE and TYPE_MODE when ODR checking types.
    
    	PR lto/91576
    	* ipa-devirt.c (odr_types_equivalent_p): Compare TREE_ADDRESSABLE and
    	TYPE_MODE.
    
    	* testsuite/g++.dg/lto/odr-8_0.C: New testcase.
    	* testsuite/g++.dg/lto/odr-8_1.C: New testcase.

Diff:
---
 gcc/ChangeLog                      |  6 ++++++
 gcc/ipa-devirt.c                   | 21 +++++++++++++++++++++
 gcc/testsuite/ChangeLog            |  6 ++++++
 gcc/testsuite/g++.dg/lto/odr-8_0.C |  7 +++++++
 gcc/testsuite/g++.dg/lto/odr-8_1.C | 12 ++++++++++++
 5 files changed, 52 insertions(+)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3816512..33ca91a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-14  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR lto/91576
+	* ipa-devirt.c (odr_types_equivalent_p): Compare TREE_ADDRESSABLE and
+	TYPE_MODE.
+
 2020-01-14  David Malcolm  <dmalcolm@redhat.com>
 
 	* Makefile.in (lang_opt_files): Add analyzer.opt.
diff --git a/gcc/ipa-devirt.c b/gcc/ipa-devirt.c
index f003195..b609a77 100644
--- a/gcc/ipa-devirt.c
+++ b/gcc/ipa-devirt.c
@@ -1544,6 +1544,27 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
       return false;
     }
 
+  if (TREE_ADDRESSABLE (t1) != TREE_ADDRESSABLE (t2)
+      && COMPLETE_TYPE_P (t1) && COMPLETE_TYPE_P (t2))
+    {
+      warn_odr (t1, t2, NULL, NULL, warn, warned,
+		G_("one type needs to be constructed while other not"));
+      gcc_checking_assert (RECORD_OR_UNION_TYPE_P (t1));
+      return false;
+    }
+  /* There is no really good user facing warning for this.
+     Either the original reason for modes being different is lost during
+     streaming or we should catch earlier warnings.  We however must detect
+     the mismatch to avoid type verifier from cmplaining on mismatched
+     types between type and canonical type. See PR91576.  */
+  if (TYPE_MODE (t1) != TYPE_MODE (t2)
+      && COMPLETE_TYPE_P (t1) && COMPLETE_TYPE_P (t2))
+    {
+      warn_odr (t1, t2, NULL, NULL, warn, warned,
+		G_("memory layout mismatch"));
+      return false;
+    }
+
   gcc_assert (!TYPE_SIZE_UNIT (t1) || !TYPE_SIZE_UNIT (t2)
 	      || operand_equal_p (TYPE_SIZE_UNIT (t1),
 				  TYPE_SIZE_UNIT (t2), 0));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8e3b910..dc42601 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-14  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR lto/91576
+	* testsuite/g++.dg/lto/odr-8_0.C: New testcase.
+	* testsuite/g++.dg/lto/odr-8_1.C: New testcase.
+
 2020-01-14  David Malcolm  <dmalcolm@redhat.com>
 
 	* gcc.dg/analyzer/CVE-2005-1689-minimal.c: New test.
diff --git a/gcc/testsuite/g++.dg/lto/odr-8_0.C b/gcc/testsuite/g++.dg/lto/odr-8_0.C
new file mode 100644
index 0000000..59f5139
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lto/odr-8_0.C
@@ -0,0 +1,7 @@
+// { dg-lto-do link }
+struct a {char c;}; // { dg-lto-message "8: 'struct a' violates the C\\+\\+ One Definition Rule" }
+int
+test (struct a *a)
+{
+  return a->c;
+}
diff --git a/gcc/testsuite/g++.dg/lto/odr-8_1.C b/gcc/testsuite/g++.dg/lto/odr-8_1.C
new file mode 100644
index 0000000..742df8c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lto/odr-8_1.C
@@ -0,0 +1,12 @@
+--- a/gcc/testsuite/g++.dg/lto/odr-8_1.C
++++ b/gcc/testsuite/g++.dg/lto/odr-8_1.C
+@@ -1,9 +1,9 @@
+struct a {char c; a() {} a(struct a &) {}}; // { dg-lto-message "one type needs to be constructed while other not" }
+extern int test (struct a *a);
+int
+main()
+{
+  struct a a;
+  a.c=0;
+  return test(&a);
+}