cppgc: Adds docs to SourceLocation

Bug: chromium:1056170
Change-Id: I89d0fbe6b73bf1b8765bb532fff58b1960fed09a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2235537
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68236}

include/cppgc/source-location.h

@@ -23,10 +23,16 @@
 
 namespace cppgc {
 
-// Encapsulates source location information. Mimics C++20's
-// std::source_location.
+/**
+ * Encapsulates source location information. Mimics C++20's
+ * std::source_location.
+ */
 class V8_EXPORT SourceLocation final {
  public:
+  /**
+   * Construct source location information corresponding to the location of the
+   * call site.
+   */
 #if CPPGC_SUPPORTS_SOURCE_LOCATION
   static constexpr SourceLocation Current(
       const char* function = __builtin_FUNCTION(),
@@ -37,12 +43,38 @@ class V8_EXPORT SourceLocation final {
   static constexpr SourceLocation Current() { return SourceLocation(); }
 #endif  // CPPGC_SUPPORTS_SOURCE_LOCATION
 
+  /**
+   * Constructs unspecified source location information.
+   */
   constexpr SourceLocation() = default;
 
+  /**
+   * Returns the name of the function associated with the position represented
+   * by this object, if any.
+   *
+   * \returns the function name as cstring.
+   */
   constexpr const char* Function() const { return function_; }
+
+  /**
+   * Returns the name of the current source file represented by this object.
+   *
+   * \returns the file name as cstring.
+   */
   constexpr const char* FileName() const { return file_; }
+
+  /**
+   * Returns the line number represented by this object.
+   *
+   * \returns the line number.
+   */
   constexpr size_t Line() const { return line_; }
 
+  /**
+   * Returns a human-readable string representing this object.
+   *
+   * \returns a human-readable string representing source location information.
+   */
   std::string ToString() const;
 
  private: