unexpected-flag-enumerator-value: fix flag detection

A non-flag enum doesn't need to have all of its enumerator
consecutive. See example added in the test, that shouldn't
warn

2 files changed, 17 insertions, 5 deletions

diff --git a/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp b/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp
index d48be74e..b953f622 100644
--- a/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp
+++ b/src/checks/manuallevel/unexpected-flag-enumerator-value.cpp
@@ -28,6 +28,8 @@
 
 #include <clang/AST/AST.h>
 
+#include <algorithm>
+
 using namespace clang;
 using namespace std;
 
@@ -75,12 +77,13 @@ static uint64_t getIntegerValue(EnumConstantDecl* e)
 static bool hasConsecutiveValues(const SmallVector<EnumConstantDecl*, 16>& enumerators)
 {
     auto val = getIntegerValue(enumerators.front());
-    bool consecutive = true;
-    for (size_t i = 1; i < enumerators.size(); ++i) {
+    const size_t until = std::min<size_t>(4, enumerators.size());
+    for (size_t i = 1; i < until; ++i) {
         val++;
-        consecutive = getIntegerValue(enumerators[i]) == val;
+        if (getIntegerValue(enumerators[i]) != val)
+            return false;
     }
-    return consecutive;
+    return true;
 }
 
 static IsFlagEnumResult isFlagEnum(const SmallVector<EnumConstantDecl*, 16>& enumerators)
diff --git a/tests/unexpected-flag-enumerator-value/main.cpp b/tests/unexpected-flag-enumerator-value/main.cpp
index bb2d19f4..3d7884df 100644
--- a/tests/unexpected-flag-enumerator-value/main.cpp
+++ b/tests/unexpected-flag-enumerator-value/main.cpp
@@ -39,7 +39,7 @@ enum AlignmentFlag {
 };
 
 // No Warning here, all consecutive values
-enum {
+enum Consecutive {
     RED = 1,
     GREEN = 2,
     BLUE = 3,
@@ -72,3 +72,12 @@ enum class WithZero {
     Four = 4,
     Eight = 8,
 };
+
+enum class AlsoConsecutive {
+    RED = 1,
+    GREEN = 2,
+    BLUE = 3,
+    BLACK = 4,
+    WHITE = 5,
+    LAST = WHITE
+};