https://bugs.gentoo.org/787851

From 6d448928a88f586195dadd9fae9cb1b19e589d94 Mon Sep 17 00:00:00 2001
From: Sam James <sam@gentoo.org>
Date: Tue, 15 Jun 2021 03:05:34 +0000
Subject: [PATCH] Fix build with GCC 11
diff --git a/src/ObjectSystem/configSymbol.hh b/src/ObjectSystem/configSymbol.hh
index 90b00d9..d037dab 100644
--- a/src/ObjectSystem/configSymbol.hh
+++ b/src/ObjectSystem/configSymbol.hh
@@ -50,7 +50,7 @@ public:
 private:
   struct symbolLt
   {
-    bool operator()(const Symbol* d1, const Symbol* d2)
+    bool operator()(const Symbol* d1, const Symbol* d2) const
     {
       return d1->compare(d2) < 0;
     }
diff --git a/src/ObjectSystem/objectMap.cc b/src/ObjectSystem/objectMap.cc
index 0dbcaf0..722aa29 100644
--- a/src/ObjectSystem/objectMap.cc
+++ b/src/ObjectSystem/objectMap.cc
@@ -50,7 +50,7 @@ ConfigSymbol::MessageQueue::markReachableNodes() const
 
 struct ConfigSymbol::dagNodeLt
 {
-  bool operator()(const DagNode* d1, const DagNode* d2)
+  bool operator()(const DagNode* d1, const DagNode* d2) const
     {
       return d1->compare(d2) < 0;
     }
diff --git a/src/ObjectSystem/objectSystemRewritingContext.hh b/src/ObjectSystem/objectSystemRewritingContext.hh
index 33785ec..32f4d94 100644
--- a/src/ObjectSystem/objectSystemRewritingContext.hh
+++ b/src/ObjectSystem/objectSystemRewritingContext.hh
@@ -62,7 +62,7 @@ protected:
 private:
   struct dagNodeLt
   {
-    bool operator()(const DagNode* d1, const DagNode* d2)
+    bool operator()(const DagNode* d1, const DagNode* d2) const
     {
       return d1->compare(d2) < 0;
     }
diff --git a/src/Mixfix/entity.hh b/src/Mixfix/entity.hh
index eb8ad58..a221de4 100644
--- a/src/Mixfix/entity.hh
+++ b/src/Mixfix/entity.hh
@@ -53,7 +53,7 @@ public:
 private:
   struct UserLt
   {
-    bool operator()(const User* user1, const User* user2)
+    bool operator()(const User* user1, const User* user2) const
     {
       //
       //   Direct < comparison of unrelated pointers is undefined. But since the casting
--
2.32.0