Imported Upstream version 6.10.0.49

Former-commit-id: 1d6753294b2993e1fbf92de9366bb9544db4189b

external/llvm-project/clang-tools-extra/docs/clang-tidy/checks/google-explicit-constructor.rst

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+.. title:: clang-tidy - google-explicit-constructor
+
+google-explicit-constructor
+===========================
+
+
+Checks that constructors callable with a single argument and conversion
+operators are marked explicit to avoid the risk of unintentional implicit
+conversions.
+
+Consider this example:
+
+.. code-block:: c++
+
+  struct S {
+    int x;
+    operator bool() const { return true; }
+  };
+
+  bool f() {
+    S a{1};
+    S b{2};
+    return a == b;
+  }
+
+The function will return ``true``, since the objects are implicitly converted to
+``bool`` before comparison, which is unlikely to be the intent.
+
+The check will suggest inserting ``explicit`` before the constructor or
+conversion operator declaration. However, copy and move constructors should not
+be explicit, as well as constructors taking a single ``initializer_list``
+argument.
+
+This code:
+
+.. code-block:: c++
+
+  struct S {
+    S(int a);
+    explicit S(const S&);
+    operator bool() const;
+    ...
+
+will become
+
+.. code-block:: c++
+
+  struct S {
+    explicit S(int a);
+    S(const S&);
+    explicit operator bool() const;
+    ...
+
+
+
+See https://google.github.io/styleguide/cppguide.html#Explicit_Constructors