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[ADT] Use adl_being/end in hasSingleElement #130506

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Merged
merged 1 commit into from
Mar 9, 2025
Merged

[ADT] Use adl_being/end in hasSingleElement #130506

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3 changes: 2 additions & 1 deletion llvm/include/llvm/ADT/STLExtras.h
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Original file line number Diff line number Diff line change
Expand Up @@ -320,7 +320,8 @@ template <typename T> class Callable<T, true> {

/// Returns true if the given container only contains a single element.
template <typename ContainerTy> bool hasSingleElement(ContainerTy &&C) {
auto B = std::begin(C), E = std::end(C);
auto B = adl_begin(C);
auto E = adl_end(C);
return B != E && std::next(B) == E;
}

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17 changes: 13 additions & 4 deletions llvm/unittests/ADT/STLExtrasTest.cpp
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Expand Up @@ -934,10 +934,19 @@ TEST(STLExtrasTest, hasSingleElement) {
const std::vector<int> V0 = {}, V1 = {1}, V2 = {1, 2};
const std::vector<int> V10(10);

EXPECT_EQ(hasSingleElement(V0), false);
EXPECT_EQ(hasSingleElement(V1), true);
EXPECT_EQ(hasSingleElement(V2), false);
EXPECT_EQ(hasSingleElement(V10), false);
EXPECT_FALSE(hasSingleElement(V0));
EXPECT_TRUE(hasSingleElement(V1));
EXPECT_FALSE(hasSingleElement(V2));
EXPECT_FALSE(hasSingleElement(V10));

// Make sure that we use the `begin`/`end` functions
// from `some_namespace`, using ADL.
some_namespace::some_struct S;
EXPECT_FALSE(hasSingleElement(S));
S.data = V1;
EXPECT_TRUE(hasSingleElement(S));
S.data = V2;
EXPECT_FALSE(hasSingleElement(S));
}

TEST(STLExtrasTest, hasNItems) {
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