Get rid of unused variables in std/algorithm/iteration

.dscanner.ini

@@ -157,7 +157,7 @@ undocumented_declaration_check="-etc.c.curl,-etc.c.odbc.sql,-etc.c.odbc.sqlext,-
 ; Checks for unused labels
 unused_label_check="-std.conv,-std.format,-std.internal.math.biguintx86,-std.regex.internal.thompson,-std.signals,-std.uni"
 ; Checks for unused variables and function parameters
-unused_variable_check="-std.algorithm.comparison,-std.algorithm.iteration,-std.algorithm.mutation,-std.algorithm.searching,-std.algorithm.setops,-std.algorithm.sorting,-std.array,-std.bigint,-std.bitmanip,-std.complex,-std.concurrency,-std.container,-std.container.array,-std.container.dlist,-std.container.rbtree,-std.container.slist,-std.conv,-std.csv,-std.datetime,-std.datetime.date,-std.datetime.interval,-std.datetime.stopwatch,-std.datetime.systime,-std.datetime.timezone,-std.digest.crc,-std.digest,-std.digest.md,-std.digest.murmurhash,-std.digest.ripemd,-std.digest.sha,-std.encoding,-std.exception,-std.experimental.allocator,-std.experimental.allocator.building_blocks.affix_allocator,-std.experimental.allocator.building_blocks.bitmapped_block,-std.experimental.allocator.building_blocks.bucketizer,-std.experimental.allocator.building_blocks.kernighan_ritchie,-std.experimental.allocator.building_blocks.stats_collector,-std.experimental.allocator.common,-std.experimental.allocator.gc_allocator,-std.experimental.allocator.mallocator,-std.experimental.allocator.typed,-std.experimental.checkedint,-std.experimental.logger.core,-std.experimental.typecons,-std.file,-std.format,-std.functional,-std.getopt,-std.internal.cstring,-std.internal.digest.sha_SSSE3,-std.internal.math.biguintcore,-std.internal.math.biguintx86,-std.internal.math.errorfunction,-std.internal.scopebuffer,-std.internal.test.dummyrange,-std.json,-std.math,-std.meta,-std.mmfile,-std.net.curl,-std.numeric,-std.parallelism,-std.process,-std.random,-std.range,-std.range.interfaces,-std.range.primitives,-std.regex.internal.backtracking,-std.regex.internal.tests,-std.regex.internal.thompson,-std.signals,-std.socket,-std.stdio,-std.string,-std.traits,-std.typecons,-std.uni,-std.uri,-std.utf,-std.uuid,-std.variant,-std.windows.registry,-std.xml,-std.zip,-std.zlib"
+unused_variable_check="-std.algorithm.comparison,-std.algorithm.mutation,-std.algorithm.searching,-std.algorithm.setops,-std.algorithm.sorting,-std.array,-std.bigint,-std.bitmanip,-std.complex,-std.concurrency,-std.container,-std.container.array,-std.container.dlist,-std.container.rbtree,-std.container.slist,-std.conv,-std.csv,-std.datetime,-std.datetime.date,-std.datetime.interval,-std.datetime.stopwatch,-std.datetime.systime,-std.datetime.timezone,-std.digest.crc,-std.digest,-std.digest.md,-std.digest.murmurhash,-std.digest.ripemd,-std.digest.sha,-std.encoding,-std.exception,-std.experimental.allocator,-std.experimental.allocator.building_blocks.affix_allocator,-std.experimental.allocator.building_blocks.bitmapped_block,-std.experimental.allocator.building_blocks.bucketizer,-std.experimental.allocator.building_blocks.kernighan_ritchie,-std.experimental.allocator.building_blocks.stats_collector,-std.experimental.allocator.common,-std.experimental.allocator.gc_allocator,-std.experimental.allocator.mallocator,-std.experimental.allocator.typed,-std.experimental.checkedint,-std.experimental.logger.core,-std.experimental.typecons,-std.file,-std.format,-std.functional,-std.getopt,-std.internal.cstring,-std.internal.digest.sha_SSSE3,-std.internal.math.biguintcore,-std.internal.math.biguintx86,-std.internal.math.errorfunction,-std.internal.scopebuffer,-std.internal.test.dummyrange,-std.json,-std.math,-std.meta,-std.mmfile,-std.net.curl,-std.numeric,-std.parallelism,-std.process,-std.random,-std.range,-std.range.interfaces,-std.range.primitives,-std.regex.internal.backtracking,-std.regex.internal.tests,-std.regex.internal.thompson,-std.signals,-std.socket,-std.stdio,-std.string,-std.traits,-std.typecons,-std.uni,-std.uri,-std.utf,-std.uuid,-std.variant,-std.windows.registry,-std.xml,-std.zip,-std.zlib"
 ; Check for useless user defined initializers
 useless_initializer="+disabled"
 ;useless_initializer="-etc.c.odbc.sqlext,-etc.c.zlib,-std.algorithm.iteration,-std.algorithm.mutation,-std.algorithm.searching,-std.algorithm.setops,-std.algorithm.sorting,-std.array,-std.bigint,-std.bitmanip,-std.compiler,-std.container.array,-std.container.dlist,-std.container.rbtree,-std.conv,-std.csv,-std.datetime.systime,-std.digest.md,-std.digest.murmurhash,-std.digest.ripemd,-std.encoding,-std.exception,-std.experimental.allocator,-std.experimental.allocator.building_blocks.bitmapped_block,-std.experimental.allocator.building_blocks.free_tree,-std.experimental.allocator.building_blocks.kernighan_ritchie,-std.experimental.allocator.common,-std.experimental.allocator.mallocator,-std.experimental.logger.core,-std.experimental.logger.multilogger,-std.file,-std.format,-std.functional,-std.getopt,-std.internal.cstring,-std.internal.digest.sha_SSSE3,-std.internal.math.biguintcore,-std.internal.math.biguintnoasm,-std.internal.math.biguintx86,-std.internal.math.gammafunction,-std.internal.test.dummyrange,-std.json,-std.math,-std.net.curl,-std.numeric,-std.parallelism,-std.path,-std.process,-std.random,-std.range,-std.range.interfaces,-std.range.primitives,-std.regex,-std.regex.internal.backtracking,-std.regex.internal.generator,-std.regex.internal.ir,-std.regex.internal.kickstart,-std.regex.internal.parser,-std.regex.internal.tests,-std.regex.internal.thompson,-std.signals,-std.socket,-std.stdio,-std.string,-std.uni,-std.uri,-std.utf,-std.uuid,-std.variant,-std.windows.registry,-std.windows.syserror,-std.xml,-std.zip,-std.zlib"

std/algorithm/iteration.d

@@ -284,10 +284,13 @@ same cost or side effects.
 
 @safe unittest
 {
-    import std.range;
+    import std.range : cycle;
+    import std.algorithm.comparison : equal;
+
     auto c = [1, 2, 3].cycle().cache();
     c = c[1 .. $];
     auto d = c[0 .. 1];
+    assert(d.equal([2]));
 }
 
 @safe unittest
@@ -686,6 +689,7 @@ private struct MapResult(alias fun, Range)
     import std.internal.test.dummyrange;
     import std.range;
     import std.typecons : tuple;
+    import std.random : unpredictableSeed, uniform, Random;
 
     int[] arr1 = [ 1, 2, 3, 4 ];
     const int[] arr1Const = arr1;
@@ -743,10 +747,14 @@ private struct MapResult(alias fun, Range)
     assert(fibsSquares.front == 9);
 
     auto repeatMap = map!"a"(repeat(1));
+    auto gen = Random(unpredictableSeed);
+    auto index = uniform(0, 1024, gen);
     static assert(isInfinite!(typeof(repeatMap)));
+    assert(repeatMap[index] == 1);
 
     auto intRange = map!"a"([1,2,3]);
     static assert(isRandomAccessRange!(typeof(intRange)));
+    assert(equal(intRange, [1, 2, 3]));
 
     foreach (DummyType; AllDummyRanges)
     {
@@ -831,6 +839,7 @@ private struct MapResult(alias fun, Range)
     import std.range;
     struct S {int* p;}
     auto m = immutable(S).init.repeat().map!"a".save;
+    assert(m.front == immutable(S)(null));
 }
 
 // each
@@ -1197,6 +1206,8 @@ private struct FilterResult(alias pred, Range)
     import std.range;
 
     auto shouldNotLoop4ever = repeat(1).filter!(x => x % 2 == 0);
+    static assert(isInfinite!(typeof(shouldNotLoop4ever)));
+    assert(!shouldNotLoop4ever.empty);
 
     int[] a = [ 3, 4, 2 ];
     auto r = filter!("a > 3")(a);
@@ -1216,6 +1227,7 @@ private struct FilterResult(alias pred, Range)
     auto infinite = filter!"a > 2"(repeat(3));
     static assert(isInfinite!(typeof(infinite)));
     static assert(isForwardRange!(typeof(infinite)));
+    assert(infinite.front == 3);
 
     foreach (DummyType; AllDummyRanges)
     {
@@ -1246,6 +1258,7 @@ private struct FilterResult(alias pred, Range)
     // With copying of inner struct Filter to Map
     auto arr = [1,2,3,4,5];
     auto m = map!"a + 1"(filter!"a < 4"(arr));
+    assert(equal(m, [2, 3, 4]));
 }
 
 @safe unittest
@@ -1262,10 +1275,6 @@ private struct FilterResult(alias pred, Range)
     assert(equal(under10, [1, 3, 5][]));
     assert(equal(under10.save, [1, 3, 5][]));
     assert(equal(under10.save, under10));
-
-    // With copying of inner struct Filter to Map
-    auto arr = [1,2,3,4,5];
-    auto m = map!"a + 1"(filter!"a < 4"(arr));
 }
 
 @safe unittest
@@ -1555,28 +1564,40 @@ if (isInputRange!R)
 
 @safe unittest
 {
+    import std.algorithm.comparison : equal;
+    import std.typecons : tuple;
+
     // Issue 13857
     immutable(int)[] a1 = [1,1,2,2,2,3,4,4,5,6,6,7,8,9,9,9];
     auto g1 = group(a1);
+    assert(equal(g1, [ tuple(1, 2u), tuple(2, 3u), tuple(3, 1u),
+                       tuple(4, 2u), tuple(5, 1u), tuple(6, 2u),
+                       tuple(7, 1u), tuple(8, 1u), tuple(9, 3u)
+                     ]));
 
     // Issue 13162
     immutable(ubyte)[] a2 = [1, 1, 1, 0, 0, 0];
     auto g2 = a2.group;
+    assert(equal(g2, [ tuple(1, 3u), tuple(0, 3u) ]));
 
     // Issue 10104
     const a3 = [1, 1, 2, 2];
     auto g3 = a3.group;
+    assert(equal(g3, [ tuple(1, 2u), tuple(2, 2u) ]));
 
     interface I {}
     class C : I {}
     const C[] a4 = [new const C()];
     auto g4 = a4.group!"a is b";
+    assert(g4.front[1] == 1);
 
     immutable I[] a5 = [new immutable C()];
     auto g5 = a5.group!"a is b";
+    assert(g5.front[1] == 1);
 
     const(int[][]) a6 = [[1], [1]];
     auto g6 = a6.group;
+    assert(equal(g6.front[0], [1]));
 }
 
 // Used by implementation of chunkBy for non-forward input ranges.
@@ -1935,24 +1956,15 @@ if (isInputRange!Range)
 version(none) // this example requires support for non-equivalence relations
 @safe unittest
 {
-    auto data = [
+    // Grouping by maximum adjacent difference:
-        [1, 1],
+    import std.math : abs;
-        [1, 2],
+    auto r3 = [1, 3, 2, 5, 4, 9, 10].chunkBy!((a, b) => abs(a-b) < 3);
-        [2, 2],
+    assert(r3.equal!equal([
-        [2, 3]
+        [1, 3, 2],
-    ];
+        [5, 4],
+        [9, 10]
+    ]));
 
-    version(none)
-    {
-        // Grouping by maximum adjacent difference:
-        import std.math : abs;
-        auto r3 = [1, 3, 2, 5, 4, 9, 10].chunkBy!((a, b) => abs(a-b) < 3);
-        assert(r3.equal!equal([
-            [1, 3, 2],
-            [5, 4],
-            [9, 10]
-        ]));
-    }
 }
 
 /// Showing usage with unary predicate:
@@ -2534,6 +2546,7 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR))
     auto j = joiner(a);
     j.front = 44;
     assert(a == [ [44, 2, 3], [42, 43] ]);
+    assert(equal(j, [44, 2, 3, 42, 43]));
 }
 
 
@@ -2956,7 +2969,9 @@ The number of seeds must be correspondingly increased.
     assert(approxEqual(r[1], 233)); // sum of squares
     // Compute average and standard deviation from the above
     auto avg = r[0] / a.length;
+    assert(avg == 5);
     auto stdev = sqrt(r[1] / a.length - avg * avg);
+    assert(cast(int) stdev == 2);
 }
 
 @safe unittest
@@ -3035,6 +3050,7 @@ The number of seeds must be correspondingly increased.
     float[] c = [ 1.2, 3, 3.3 ];
     auto r = reduce!"a + b"(a, b);
     r = reduce!"a + b"(a, c);
+    assert(r == 7.5);
 }
 
 @safe unittest
@@ -3065,7 +3081,6 @@ The number of seeds must be correspondingly increased.
 
 @system unittest
 {
-    int i = 0;
     static struct OpApply
     {
         int opApply(int delegate(ref int) dg)
@@ -3095,10 +3110,12 @@ The number of seeds must be correspondingly increased.
         auto e = reduce!(fun)(0, OpApply());
         auto f = reduce!(fun, fun)(tuple(0, 0), OpApply());
 
-        return max(a, b.expand, c, d.expand);
+        return max(a, b.expand, c, d.expand, e, f.expand);
     }
     auto a = foo();
+    assert(a == 9);
     enum b = foo();
+    assert(b == 9);
 }
 
 @safe unittest
@@ -3115,7 +3132,7 @@ The number of seeds must be correspondingly increased.
         return reduce!(F, G)(tuple(ElementType!R.max,
                                    ElementType!R.min), range);
     }
-    assert(minmaxElement([1, 2, 3])== tuple(1, 3));
+    assert(minmaxElement([1, 2, 3]) == tuple(1, 3));
 }
 
 @safe unittest //12569
@@ -3142,7 +3159,8 @@ The number of seeds must be correspondingly increased.
 @safe unittest //13304
 {
     int[] data;
-    static assert(is(typeof(reduce!((a, b)=>a+b)(data))));
+    static assert(is(typeof(reduce!((a, b) => a + b)(data))));
+    assert(data.length == 0);
 }
 
 //Helper for Reduce
@@ -3242,6 +3260,7 @@ if (fun.length >= 1)
     static assert(!is(typeof(arr.fold!(a => a))));
     static assert(is(typeof(arr.fold!((a, b) => a))));
     static assert(is(typeof(arr.fold!((a, b) => a)(1))));
+    assert(arr.length == 1);
 }
 
 /++
@@ -4870,8 +4889,7 @@ private auto sumKahan(Result, R)(Result result, R r)
     static assert(is(typeof(sum([1.0, 2.0, 3.0, 4.0])) == double));
     static assert(is(typeof(sum([ 1F,  2F,  3F,  4F])) == double));
     const(float[]) a = [1F, 2F, 3F, 4F];
-    static assert(is(typeof(sum(a)) == double));
+    assert(sum(a) == 10F);
-    const(float)[] b = [1F, 2F, 3F, 4F];
     static assert(is(typeof(sum(a)) == double));
 
     double[] empty;
@@ -4899,8 +4917,10 @@ private auto sumKahan(Result, R)(Result result, R r)
 @safe pure nothrow unittest // 12434
 {
     immutable a = [10, 20];
-    auto s1 = sum(a);             // Error
+    auto s1 = sum(a);
-    auto s2 = a.map!(x => x).sum; // Error
+    assert(s1 == 30);
+    auto s2 = a.map!(x => x).sum;
+    assert(s2 == 30);
 }
 
 @system unittest