!53 [C++] Fix interaction between aka changes and DR1558 (PR92206)

From: @eastb233
Reviewed-by: @jdkboy
Signed-off-by: @jdkboy

Fix-interaction-between-aka-changes-and-DR1558.patch

@@ -0,0 +1,98 @@
+This backport contains 1 patch from gcc main stream tree.
+The commit id of these patchs list as following in the order of time.
+
+0001-Fix-interaction-between-aka-changes-and-DR1558.patch
+ae83b9deb87787371cd94b4417e160d41dd0322c
+
+diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
+index adc021b2a5c..42afe1bd5cb 100644
+--- a/gcc/cp/cp-tree.h
++++ b/gcc/cp/cp-tree.h
+@@ -5759,8 +5759,13 @@ enum auto_deduction_context
+ 
+    STF_USER_VISIBLE: use heuristics to try to avoid stripping user-facing
+        aliases of internal details.  This is intended for diagnostics,
+-       where it should (for example) give more useful "aka" types.  */
++       where it should (for example) give more useful "aka" types.
++
++   STF_STRIP_DEPENDENT: allow the stripping of aliases with dependent
++       template parameters, relying on code elsewhere to report any
++       appropriate diagnostics.  */
+ const unsigned int STF_USER_VISIBLE = 1U;
++const unsigned int STF_STRIP_DEPENDENT = 1U << 1;
+ 
+ /* Returns the TEMPLATE_DECL associated to a TEMPLATE_TEMPLATE_PARM
+    node.  */
+diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
+index ba635d4ddbd..6c39c004b01 100644
+--- a/gcc/cp/tree.c
++++ b/gcc/cp/tree.c
+@@ -1488,7 +1488,8 @@ strip_typedefs (tree t, bool *remove_attributes, unsigned int flags)
+   if (t == TYPE_CANONICAL (t))
+     return t;
+ 
+-  if (dependent_alias_template_spec_p (t))
++  if (!(flags & STF_STRIP_DEPENDENT)
++      && dependent_alias_template_spec_p (t))
+     /* DR 1558: However, if the template-id is dependent, subsequent
+        template argument substitution still applies to the template-id.  */
+     return t;
+@@ -1673,7 +1674,8 @@ strip_typedefs (tree t, bool *remove_attributes, unsigned int flags)
+ 	      && !user_facing_original_type_p (t))
+ 	    return t;
+ 	  result = strip_typedefs (DECL_ORIGINAL_TYPE (TYPE_NAME (t)),
+-				   remove_attributes, flags);
++				   remove_attributes,
++				   flags | STF_STRIP_DEPENDENT);
+ 	}
+       else
+ 	result = TYPE_MAIN_VARIANT (t);
+diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-1.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-1.C
+new file mode 100644
+index 00000000000..c3f7b1977db
+--- /dev/null
++++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-1.C
+@@ -0,0 +1,9 @@
++// { dg-require-effective-target c++11 }
++
++template<typename> struct A {};
++template<typename T1, typename T2 = typename T1::value> using alias1 = A<T1>;
++template<typename T> class B {
++  using alias2 = alias1<A<T>>; // { dg-error {no type named 'value'} }
++  A<alias2> a; // { dg-bogus {no type named 'value'} }
++};
++B<int> b;
+diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-2.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-2.C
+new file mode 100644
+index 00000000000..31d73d6bad3
+--- /dev/null
++++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-2.C
+@@ -0,0 +1,14 @@
++// { dg-require-effective-target c++11 }
++
++template <bool> struct A;
++class Vector {
++  template <typename> struct TypeIsGCThing {
++    template <typename T, typename A<T ::value>::Type> using Vector = Vector;
++    struct B;
++    template <typename> class ContainerIter {
++      using Action = B;
++      using ActionVector = Vector<Action, 0>;
++      ContainerIter<ActionVector> a;
++    };
++  };
++};
+diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-3.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-3.C
+new file mode 100644
+index 00000000000..6698a366411
+--- /dev/null
++++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-pr92206-3.C
+@@ -0,0 +1,8 @@
++// { dg-require-effective-target c++11 }
++
++template <typename> void a();
++template <typename> struct b;
++template <bool> using c = int;
++template <typename d, typename e = decltype(a<d>)> using f = e;
++template <typename e> using g = f<e>;
++template <typename h> c<b<g<h>>::i> j;

gcc.spec

@@ -1,4 +1,4 @@
-%global DATE 20210104
+%global DATE 20210115
 
 %global gcc_version 9.3.1
 %global gcc_major 9.3.1
@@ -59,7 +59,7 @@
 Summary: Various compilers (C, C++, Objective-C, ...)
 Name: gcc
 Version: %{gcc_version}
-Release: %{DATE}.14
+Release: %{DATE}.15
 License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ with exceptions and LGPLv2+ and BSD
 URL: https://gcc.gnu.org
 
@@ -220,6 +220,7 @@ Patch103: re-PR-target-91124-gcc.target-i386-avx512vl-vpshldvd.patch
 Patch104: fix-avx512vl-vcvttpd2dq-2-fail.patch
 Patch105: fix-issue604-ldist-dependency-fixup.patch
 Patch106: Apply-maximum-nunits-for-BB-SLP.patch
+Patch107: Fix-interaction-between-aka-changes-and-DR1558.patch
 
 
 %global gcc_target_platform %{_arch}-linux-gnu
@@ -769,6 +770,7 @@ not stable, so plugins must be rebuilt any time GCC is updated.
 %patch104 -p1
 %patch105 -p1
 %patch106 -p1
+%patch107 -p1
 
 
 %build
@@ -2700,6 +2702,9 @@ end
 %doc rpm.doc/changelogs/libcc1/ChangeLog*
 
 %changelog
+* Fri Jan 15 2021 eastb233 <xiezhiheng@huawei.com> - 9.3.1-20210115.15
+- Fix-interaction-between-aka-changes-and-DR1558.patch: New file
+
 * Mon Jan 04 2021 eastb233 <xiezhiheng@huawei.com> - 9.3.1-20210104.14
 - gcc.spec: Pack arm_bf16.h and arm_sve.h in aarch64 port