[llvm] [ADT] Add unit tests for set_subtract (PR #99561)

[Kazu Hirata via llvm-commits]

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@@ -199,6 +201,42 @@ TEST(SetOperationsTest, SetSubtract) {
   EXPECT_EQ(ExpectedSet2, Set2);
 }
 
+TEST(SetOperationsTest, SetSubtractSmallPtrSet) {
+  int A[4];
+
+  // Set1.size() < Set2.size()
+  SmallPtrSet<int *, 4> Set1 = {&A[0], &A[1]};
+  SmallPtrSet<int *, 4> Set2 = {&A[1], &A[2], &A[3]};
+  SmallPtrSet<int *, 4> ExpectedSet1 = {&A[0]};
+  set_subtract(Set1, Set2);
+  EXPECT_EQ(ExpectedSet1, Set1);
+
+  // Set1.size() > Set2.size()
+  Set1 = {&A[0], &A[1], &A[2]};
+  Set2 = {&A[0], &A[2]};
+  ExpectedSet1 = {&A[1]};
+  set_subtract(Set1, Set2);
+  EXPECT_EQ(ExpectedSet1, Set1);
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kazutakahirata wrote:

I've switched to `testing::UnorderedEelementsAre` in the latest iteration.  Thanks!

https://github.com/llvm/llvm-project/pull/99561