From 4e5e4899d5ce612616511506b2fb33ec81230f8e Mon Sep 17 00:00:00 2001
From: Marco Bubke <marco.bubke@qt.io>
Date: Tue, 16 Jul 2019 20:42:54 +0200
Subject: [PATCH] Clang: Improve modified timer checker

Make the algorithm a little bit more clear.

Change-Id: I71b04cdd947272edf9fade8f93b7300a945a2fc8
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>
---
 src/libs/clangsupport/modifiedtimechecker.h   |  4 ++--
 src/libs/clangsupport/set_algorithm.h         |  6 +++---
 .../unittest/modifiedtimechecker-test.cpp     | 21 ++++++++++++++-----
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/libs/clangsupport/modifiedtimechecker.h b/src/libs/clangsupport/modifiedtimechecker.h
index 00e8e3ebacf..0b7f97c5a34 100644
--- a/src/libs/clangsupport/modifiedtimechecker.h
+++ b/src/libs/clangsupport/modifiedtimechecker.h
@@ -83,12 +83,12 @@ public:
 private:
     bool compareEntries(const SourceEntries &sourceEntries) const
     {
-        return set_intersection_compare(
+        return !set_intersection_compare(
             m_currentSourceTimeStamps.begin(),
             m_currentSourceTimeStamps.end(),
             sourceEntries.begin(),
             sourceEntries.end(),
-            [](auto first, auto second) { return second.timeStamp > first.timeStamp; },
+            [](auto first, auto second) { return first.timeStamp > second.timeStamp; },
             [](auto first, auto second) { return first.sourceId < second.sourceId; });
     }
 
diff --git a/src/libs/clangsupport/set_algorithm.h b/src/libs/clangsupport/set_algorithm.h
index 39bd3a2055b..dae2b019335 100644
--- a/src/libs/clangsupport/set_algorithm.h
+++ b/src/libs/clangsupport/set_algorithm.h
@@ -89,13 +89,13 @@ bool set_intersection_compare(
             ++first1;
         } else {
             if (!comp(*first2, *first1)) {
-                if (call(*first2, *first1++))
-                    return false;
+                if (call(*first1++, *first2))
+                    return true;
             }
             ++first2;
         }
     }
 
-    return true;
+    return false;
 }
 } // namespace ClangBackEnd
diff --git a/tests/unit/unittest/modifiedtimechecker-test.cpp b/tests/unit/unittest/modifiedtimechecker-test.cpp
index 0e18228ac3c..a2e97ccadac 100644
--- a/tests/unit/unittest/modifiedtimechecker-test.cpp
+++ b/tests/unit/unittest/modifiedtimechecker-test.cpp
@@ -50,13 +50,17 @@ protected:
 
     NiceMock<MockFileSystem> mockFileSystem;
     ClangBackEnd::ModifiedTimeChecker<> checker{mockFileSystem};
-    SourceEntries upToDateEntries = {{1, SourceType::UserInclude, 100},
+    SourceEntries upToDateEntries = {{1, SourceType::UserInclude, 51},
                                      {2, SourceType::SystemInclude, 30},
-                                     {3, SourceType::UserInclude, 100},
-                                     {4, SourceType::SystemInclude, 30}};
+                                     {3, SourceType::UserInclude, 50},
+                                     {4, SourceType::SystemInclude, 31}};
+    SourceEntries equalEntries = {{1, SourceType::UserInclude, 50},
+                                  {2, SourceType::SystemInclude, 30},
+                                  {3, SourceType::UserInclude, 50},
+                                  {4, SourceType::SystemInclude, 30}};
     SourceEntries notUpToDateEntries = {{1, SourceType::UserInclude, 50},
-                                        {2, SourceType::SystemInclude, 20},
-                                        {3, SourceType::UserInclude, 100},
+                                        {2, SourceType::SystemInclude, 29},
+                                        {3, SourceType::UserInclude, 50},
                                         {4, SourceType::SystemInclude, 30}};
 };
 
@@ -67,6 +71,13 @@ TEST_F(ModifiedTimeChecker, IsUpToDate)
     ASSERT_TRUE(isUpToDate);
 }
 
+TEST_F(ModifiedTimeChecker, EqualEntriesAreUpToDate)
+{
+    auto isUpToDate = checker.isUpToDate(equalEntries);
+
+    ASSERT_TRUE(isUpToDate);
+}
+
 TEST_F(ModifiedTimeChecker, IsUpToDateSecondRun)
 {
     checker.isUpToDate(upToDateEntries);