[clang][dataflow] Fix MapLattice::insert() to not drop return value

Fix `MapLattice` API to return `std::pair<iterator, bool>`,
allowing users to detect when an element has been inserted without
performing a redundant map lookup.

Differential Revision: https://reviews.llvm.org/D130497

1 files changed, 7 insertions, 2 deletions

diff --git a/clang/unittests/Analysis/FlowSensitive/MapLatticeTest.cpp b/clang/unittests/Analysis/FlowSensitive/MapLatticeTest.cpp
index d3436e8..f6fe81e 100644
--- a/clang/unittests/Analysis/FlowSensitive/MapLatticeTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/MapLatticeTest.cpp
@@ -50,13 +50,18 @@ static constexpr int Key1 = 0;
 static constexpr int Key2 = 1;
 
 namespace {
+using ::testing::_;
 using ::testing::Pair;
 using ::testing::UnorderedElementsAre;
 
 TEST(MapLatticeTest, InsertWorks) {
   MapLattice<int, BooleanLattice> Lattice;
-  Lattice.insert({Key1, BooleanLattice(false)});
-  Lattice.insert({Key2, BooleanLattice(false)});
+  EXPECT_THAT(Lattice.insert({Key1, BooleanLattice(false)}), Pair(_, true));
+  EXPECT_THAT(Lattice.insert({Key2, BooleanLattice(false)}), Pair(_, true));
+
+  // Insertion fails on collision.
+  EXPECT_THAT(Lattice.insert({Key1, BooleanLattice(false)}), Pair(_, false));
+  EXPECT_THAT(Lattice.insert({Key2, BooleanLattice(false)}), Pair(_, false));
 
   EXPECT_THAT(Lattice, UnorderedElementsAre(Pair(Key1, BooleanLattice(false)),
                                             Pair(Key2, BooleanLattice(false))));