From d81dd594c7dc6aeef94e8dec710aa1ff96e42e1c Mon Sep 17 00:00:00 2001
From: Anton Volokhov <avolokhov@apple.com>
Date: Fri, 18 Sep 2020 14:19:46 +0100
Subject: [PATCH 1/3] fix Buckets to not throw fatal error

---
 Sources/Prometheus/MetricTypes/Histogram.swift |  4 ++--
 Tests/SwiftPrometheusTests/BucketsTests.swift  | 13 +++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 Tests/SwiftPrometheusTests/BucketsTests.swift

diff --git a/Sources/Prometheus/MetricTypes/Histogram.swift b/Sources/Prometheus/MetricTypes/Histogram.swift
index a16396b..e832d05 100644
--- a/Sources/Prometheus/MetricTypes/Histogram.swift
+++ b/Sources/Prometheus/MetricTypes/Histogram.swift
@@ -42,7 +42,7 @@ public struct Buckets: ExpressibleByArrayLiteral {
         var arr = [Double]()
         var s = start
         for x in 0..<count {
-            arr[x] = s
+            arr.append(s)
             s += width
         }
         return Buckets(arr)
@@ -61,7 +61,7 @@ public struct Buckets: ExpressibleByArrayLiteral {
         var arr = [Double]()
         var s = start
         for x in 0..<count {
-            arr[x] = s
+            arr.append(s)
             s *= factor
         }
         return Buckets(arr)
diff --git a/Tests/SwiftPrometheusTests/BucketsTests.swift b/Tests/SwiftPrometheusTests/BucketsTests.swift
new file mode 100644
index 0000000..e00425a
--- /dev/null
+++ b/Tests/SwiftPrometheusTests/BucketsTests.swift
@@ -0,0 +1,13 @@
+import XCTest
+import Prometheus
+class BucketsTests: XCTestCase {
+    func testExponentialDoesNotThrow() {
+        let buckets = Buckets.exponential(start: 1, factor: 2, count: 4)
+        XCTAssertEqual([1.0, 2.0, 4.0, 8.0, Double.greatestFiniteMagnitude], buckets.buckets)
+    }
+
+    func testLinearDoesNotThrow() {
+        let buckets = Buckets.linear(start: 1, width: 20, count: 4)
+        XCTAssertEqual([1, 21, 41, 61, Double.greatestFiniteMagnitude], buckets.buckets)
+    }
+}

From 3741af3a988198f06cdcf9854cfdf775c58c41cd Mon Sep 17 00:00:00 2001
From: Anton Volokhov <avolokhov@apple.com>
Date: Wed, 3 Mar 2021 14:43:36 +0000
Subject: [PATCH 2/3] fix compiler warning

---
 Sources/Prometheus/MetricTypes/Histogram.swift | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sources/Prometheus/MetricTypes/Histogram.swift b/Sources/Prometheus/MetricTypes/Histogram.swift
index e832d05..ff71584 100644
--- a/Sources/Prometheus/MetricTypes/Histogram.swift
+++ b/Sources/Prometheus/MetricTypes/Histogram.swift
@@ -41,7 +41,7 @@ public struct Buckets: ExpressibleByArrayLiteral {
         assert(count >= 1, "Bucket.linear needs a count larger than 1")
         var arr = [Double]()
         var s = start
-        for x in 0..<count {
+        for _ in 0..<count {
             arr.append(s)
             s += width
         }
@@ -60,7 +60,7 @@ public struct Buckets: ExpressibleByArrayLiteral {
         assert(factor > 1, "Bucket.exponential needs a factor larger than 1")
         var arr = [Double]()
         var s = start
-        for x in 0..<count {
+        for _ in 0..<count {
             arr.append(s)
             s *= factor
         }

From 2d6c7921a143e7f4f351c1a1da589b531e4e5fac Mon Sep 17 00:00:00 2001
From: Anton Volokhov <avolokhov@apple.com>
Date: Wed, 3 Mar 2021 15:20:53 +0000
Subject: [PATCH 3/3] simplify linear buckets creation

---
 Sources/Prometheus/MetricTypes/Histogram.swift | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/Sources/Prometheus/MetricTypes/Histogram.swift b/Sources/Prometheus/MetricTypes/Histogram.swift
index ff71584..298033b 100644
--- a/Sources/Prometheus/MetricTypes/Histogram.swift
+++ b/Sources/Prometheus/MetricTypes/Histogram.swift
@@ -39,12 +39,7 @@ public struct Buckets: ExpressibleByArrayLiteral {
     ///     - count: Amount of buckets to generate, should be larger than zero. The +Inf bucket is not included in this count.
     public static func linear(start: Double, width: Double, count: Int) -> Buckets {
         assert(count >= 1, "Bucket.linear needs a count larger than 1")
-        var arr = [Double]()
-        var s = start
-        for _ in 0..<count {
-            arr.append(s)
-            s += width
-        }
+        let arr = (0..<count).map { Double(start) + Double($0) * Double(width) }
         return Buckets(arr)
     }