[gcc r8-10022] c++: Fix thinko in enum_min_precision [PR61414]

[Jakub Jelinek]

https://gcc.gnu.org/g:53073523bca574251d45bded65b2b0c183b01e5d

commit r8-10022-g53073523bca574251d45bded65b2b0c183b01e5d
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Feb 14 17:36:00 2020 +0100

    c++: Fix thinko in enum_min_precision [PR61414]
    
    When backporting the PR61414 fix to 8.4, I've noticed that the caching
    of prec is actually broken, as it would fail to actually store the computed
    precision into the hash_map's value and so next time we'd think the enum needs
    0 bits.
    
    2020-02-14  Jakub Jelinek  <jakub@redhat.com>
    
    	PR c++/61414
    	* class.c (enum_min_precision): Change prec type from int to int &.
    
    	* g++.dg/cpp0x/enum39.C: New test.

Diff:
---
 gcc/cp/ChangeLog                    |  5 +++++
 gcc/cp/class.c                      |  2 +-
 gcc/testsuite/ChangeLog             |  5 +++++
 gcc/testsuite/g++.dg/cpp0x/enum39.C | 15 +++++++++++++++
 4 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 85d29d3..4df333c 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,10 @@
 2020-02-14  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/61414
+	* class.c (enum_min_precision): Change prec type from int to int &.
+
+2020-02-14  Jakub Jelinek  <jakub@redhat.com>
+
 	Backported from mainline
 	2020-01-17  Jakub Jelinek  <jakub@redhat.com>
 
diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 38137f9..07ce489 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -3216,7 +3216,7 @@ enum_min_precision (tree type)
     enum_to_min_precision = hash_map<tree, int>::create_ggc (37);
 
   bool existed;
-  int prec = enum_to_min_precision->get_or_insert (type, &existed);
+  int &prec = enum_to_min_precision->get_or_insert (type, &existed);
   if (existed)
     return prec;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0b321a8..3c785be 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2020-02-14  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/61414
+	* g++.dg/cpp0x/enum39.C: New test.
+
+2020-02-14  Jakub Jelinek  <jakub@redhat.com>
+
 	Backported from mainline
 	2020-02-13  Jakub Jelinek  <jakub@redhat.com>
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/enum39.C b/gcc/testsuite/g++.dg/cpp0x/enum39.C
new file mode 100644
index 0000000..676cf84
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/enum39.C
@@ -0,0 +1,15 @@
+// PR c++/61414
+// { dg-do compile { target c++11 } }
+
+enum class E { E0 = -4, E1 = 3 };
+enum F : unsigned { F0 = 0, F1 = 15 };
+
+struct S
+{
+  E a : 2;	// { dg-warning "'S::a' is too small to hold all values of 'enum class E'" }
+  E b : 2;	// { dg-warning "'S::b' is too small to hold all values of 'enum class E'" }
+  E c : 3;	// { dg-bogus "'S::c' is too small to hold all values of 'enum class E'" }
+  F d : 3;	// { dg-warning "'S::d' is too small to hold all values of 'enum F'" }
+  F e : 3;	// { dg-warning "'S::e' is too small to hold all values of 'enum F'" }
+  F f : 4;	// { dg-bogus "'S::f' is too small to hold all values of 'enum F'" }
+};