Add some documentation stating that the memory allocated by the ASTContext.h placement new does not need to be explicitly freed

[rnk]

Thanks, lgtm!

include/clang/AST/ASTContext.h

2360–2361

Context.Deallocate() is a noop, so I think this last sentence is incorrect. I'd delete it or shorten to "Note that you cannot use delete on the pointer."

2399–2400

Ditto

[• ehsan]

Closed by commit rL218232 (authored by @ehsan).

include/clang/AST/ASTContext.h

 ///
 /// Usage looks like this (assuming there's an ASTContext 'Context' in scope):
 /// @code
 /// // Default alignment (8)
 /// IntegerLiteral *Ex = new (Context) IntegerLiteral(arguments);
 /// // Specific alignment
 /// IntegerLiteral *Ex2 = new (Context, 4) IntegerLiteral(arguments);
 /// @endcode
-/// Please note that you cannot use delete on the pointer; it must be
-/// deallocated using an explicit destructor call followed by
+/// Memory allocated through this placement new operator does not need to be
+/// explicitly freed, as ASTContext will free all of this memory when it gets
+/// destroyed. Please note that you cannot use delete on the pointer; it must
+/// be deallocated using an explicit destructor call followed by
 /// @c Context.Deallocate(Ptr).
 ///
 /// @param Bytes The number of bytes to allocate. Calculated by the compiler.
 /// @param C The ASTContext that provides the allocator.
 /// @param Alignment The alignment of the allocated memory (if the underlying
 ///                  allocator supports it).
 /// @return The allocated memory. Could be NULL.
 inline void *operator new(size_t Bytes, const clang::ASTContext &C,

 ///
 /// Usage looks like this (assuming there's an ASTContext 'Context' in scope):
 /// @code
 /// // Default alignment (8)
 /// char *data = new (Context) char[10];
 /// // Specific alignment
 /// char *data = new (Context, 4) char[10];
 /// @endcode
-/// Please note that you cannot use delete on the pointer; it must be
-/// deallocated using an explicit destructor call followed by
+/// Memory allocated through this placement new[] operator does not need to be
+/// explicitly freed, as ASTContext will free all of this memory when it gets
+/// destroyed. Please note that you cannot use delete on the pointer; it must
+/// be deallocated using an explicit destructor call followed by
 /// @c Context.Deallocate(Ptr).
 ///
 /// @param Bytes The number of bytes to allocate. Calculated by the compiler.
 /// @param C The ASTContext that provides the allocator.
 /// @param Alignment The alignment of the allocated memory (if the underlying
 ///                  allocator supports it).
 /// @return The allocated memory. Could be NULL.
 inline void *operator new[](size_t Bytes, const clang::ASTContext& C,