[gcc r10-7094] c++: Readd [LR]ROTATE_EXPR support to constexpr.c [PR94067]

[Jakub Jelinek]

https://gcc.gnu.org/g:81fa6d7321dd9b645d86de4a8a6967c603f176e3

commit r10-7094-g81fa6d7321dd9b645d86de4a8a6967c603f176e3
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Mar 9 21:52:18 2020 +0100

    c++: Readd [LR]ROTATE_EXPR support to constexpr.c [PR94067]
    
    Since r10-6527-gaaa26bf496a646778ac861aed124d960b5bf549f fold_for_warn
    will perform maybe_constant_value even on some cp_fold produced trees and
    so can include rotate exprs which were removed last fall from constexpr.c
    
    2020-03-09  Jakub Jelinek  <jakub@redhat.com>
    
            PR c++/94067
            Revert
            2019-10-11  Paolo Carlini  <paolo.carlini@oracle.com>
    
            * constexpr.c (cxx_eval_constant_expression): Do not handle
            RROTATE_EXPR and LROTATE_EXPR.
    
            * g++.dg/warn/Wconversion-pr94067.C: New test.

Diff:
---
 gcc/cp/ChangeLog                                | 9 +++++++++
 gcc/cp/constexpr.c                              | 4 ++++
 gcc/testsuite/ChangeLog                         | 5 +++++
 gcc/testsuite/g++.dg/warn/Wconversion-pr94067.C | 9 +++++++++
 4 files changed, 27 insertions(+)

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 5fc3e7def6b..7b3b9560571 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,12 @@
+2020-03-09  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/94067
+	Revert
+	2019-10-11  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* constexpr.c (cxx_eval_constant_expression): Do not handle
+	RROTATE_EXPR and LROTATE_EXPR.
+
 2020-03-09  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/94050 - ABI issue with alignas on armv7hl.
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 521c87f6210..76af0d710c4 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -5730,6 +5730,8 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
     case MAX_EXPR:
     case LSHIFT_EXPR:
     case RSHIFT_EXPR:
+    case LROTATE_EXPR:
+    case RROTATE_EXPR:
     case BIT_IOR_EXPR:
     case BIT_XOR_EXPR:
     case BIT_AND_EXPR:
@@ -7853,6 +7855,8 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
     case MAX_EXPR:
     case LSHIFT_EXPR:
     case RSHIFT_EXPR:
+    case LROTATE_EXPR:
+    case RROTATE_EXPR:
     case BIT_IOR_EXPR:
     case BIT_XOR_EXPR:
     case BIT_AND_EXPR:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6c0fab65420..44f65ffa204 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-09  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/94067
+	* g++.dg/warn/Wconversion-pr94067.C: New test.
+
 2020-03-09  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/94050 - ABI issue with alignas on armv7hl.
diff --git a/gcc/testsuite/g++.dg/warn/Wconversion-pr94067.C b/gcc/testsuite/g++.dg/warn/Wconversion-pr94067.C
new file mode 100644
index 00000000000..c1031017a1f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wconversion-pr94067.C
@@ -0,0 +1,9 @@
+// PR c++/94067
+// { dg-do compile }
+// { dg-options "-Wconversion" }
+
+static inline unsigned short
+swap (unsigned short x)
+{
+  return (x >> 8) | static_cast<unsigned short>(x << 8);
+}