[llvm] [YAML] Make `std::array` available (PR #116059)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-support

Author: NAKAMURA Takumi (chapuni)

<details>
<summary>Changes</summary>

`std::array` will be handled like `MutableArrayRef`;

- Extending elements is not acceptable.
- For applying fewer sequence, trailing elements will be initialized by default.

Not like;

- `std::array` is not the reference but holds values. Supposing to hold small count of elements.

---
Full diff: https://github.com/llvm/llvm-project/pull/116059.diff


2 Files Affected:

- (modified) llvm/include/llvm/Support/YAMLTraits.h (+5) 
- (modified) llvm/unittests/Support/YAMLIOTest.cpp (+32-15) 


``````````diff
diff --git a/llvm/include/llvm/Support/YAMLTraits.h b/llvm/include/llvm/Support/YAMLTraits.h
index 1d04783753d5cd..45d82f3ebefa9c 100644
--- a/llvm/include/llvm/Support/YAMLTraits.h
+++ b/llvm/include/llvm/Support/YAMLTraits.h
@@ -2006,6 +2006,11 @@ struct SequenceTraits<
     std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
     : SequenceTraitsImpl<std::vector<T>, SequenceElementTraits<T>::flow> {};
 template <typename T, unsigned N>
+struct SequenceTraits<
+    std::array<T, N>,
+    std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
+    : SequenceTraitsImpl<std::array<T, N>, SequenceElementTraits<T>::flow> {};
+template <typename T, unsigned N>
 struct SequenceTraits<
     SmallVector<T, N>,
     std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
diff --git a/llvm/unittests/Support/YAMLIOTest.cpp b/llvm/unittests/Support/YAMLIOTest.cpp
index e10fe099a30adb..a7d1b338719f3b 100644
--- a/llvm/unittests/Support/YAMLIOTest.cpp
+++ b/llvm/unittests/Support/YAMLIOTest.cpp
@@ -3366,20 +3366,38 @@ struct FixedArray {
   int values[4];
 };
 
+struct StdArray {
+  StdArray() {
+    // Initialize to int max as a sentinel value.
+    for (auto &v : values)
+      v = std::numeric_limits<int>::max();
+  }
+  std::array<int, 4> values;
+};
+
 namespace llvm {
 namespace yaml {
-  template <>
-  struct MappingTraits<FixedArray> {
-    static void mapping(IO &io, FixedArray& st) {
-      MutableArrayRef<int> array = st.values;
-      io.mapRequired("Values", array);
-    }
-  };
-}
-}
+template <> struct MappingTraits<FixedArray> {
+  static void mapping(IO &io, FixedArray &st) {
+    MutableArrayRef<int> array = st.values;
+    io.mapRequired("Values", array);
+  }
+};
+template <> struct MappingTraits<StdArray> {
+  static void mapping(IO &io, StdArray &st) {
+    io.mapRequired("Values", st.values);
+  }
+};
+} // namespace yaml
+} // namespace llvm
+
+using TestTypes = ::testing::Types<FixedArray, StdArray>;
 
-TEST(YAMLIO, FixedSizeArray) {
-  FixedArray faval;
+template <typename T> class YAMLIO : public testing::Test {};
+TYPED_TEST_SUITE(YAMLIO, TestTypes, );
+
+TYPED_TEST(YAMLIO, FixedSizeArray) {
+  TypeParam faval;
   Input yin("---\nValues:  [ 1, 2, 3, 4 ]\n...\n");
   yin >> faval;
 
@@ -3401,9 +3419,9 @@ TEST(YAMLIO, FixedSizeArray) {
   ASSERT_EQ(serialized, expected);
 }
 
-TEST(YAMLIO, FixedSizeArrayMismatch) {
+TYPED_TEST(YAMLIO, FixedSizeArrayMismatch) {
   {
-    FixedArray faval;
+    TypeParam faval;
     Input yin("---\nValues:  [ 1, 2, 3 ]\n...\n");
     yin >> faval;
 
@@ -3416,12 +3434,11 @@ TEST(YAMLIO, FixedSizeArrayMismatch) {
   }
 
   {
-    FixedArray faval;
+    TypeParam faval;
     Input yin("---\nValues:  [ 1, 2, 3, 4, 5 ]\n...\n");
     yin >> faval;
 
     // Error for too many elements.
     EXPECT_TRUE(!!yin.error());
   }
-
 }

``````````

</details>


https://github.com/llvm/llvm-project/pull/116059