Format and cleanup site/source/docs/api_reference/advanced-apis.rst. NFC (#16523)

- Use hyperlinks in footnotes to make the source easier to read
- Reformat at 80 columns
- Remove redundant/out-of-date note about "The small number of options
  that developers may have cause to change" (this is covered above
  and also not so true anymore since we have settings_internal)

Author: sbc100

site/source/docs/api_reference/advanced-apis.rst

@@ -4,7 +4,10 @@
 Advanced APIs
 =============
 
-This section lists APIs that are not suitable for general use, but which may be useful to developers in some circumstances. These include APIs that are difficult or complicated to use, or which are intended primarily for developers working on the Emscripten core.
+This section lists APIs that are not suitable for general use, but which may be
+useful to developers in some circumstances. These include APIs that are
+difficult or complicated to use, or which are intended primarily for developers
+working on the Emscripten core.
 
 .. contents:: Table of Contents
     :local:
@@ -14,42 +17,51 @@ This section lists APIs that are not suitable for general use, but which may be
 .. _settings-js:
 
 settings.js
-============
-
-`settings.js <https://github.com/emscripten-core/emscripten/blob/main/src/settings.js>`_ contains default values and options used in various places by the compiler.
+===========
 
-.. Warning :: Many **settings.js** options are highly brittle - certain combinations of options, and combinations of certain options used with some source code, can cause Emscripten to fail badly. This is intended for use by "advanced users", and possibly even only people developing Emscripten itself.
+`settings.js`_ contains default values and options used in various places by the
+compiler.
 
+.. Warning:: Many **settings.js** options are highly brittle - certain
+   combinations of options, and combinations of certain options used with some
+   source code, can cause Emscripten to fail badly. This is intended for use by
+   "advanced users", and possibly even only people developing Emscripten itself.
 
-The options in **settings.js** are normally set as command line parameters to *emcc*: ::
+The options in **settings.js** are normally set as command line parameters to
+*emcc*::
 
   emcc -s OPT=VALUE
 
-
-While it is possible to edit **settings.js** manually, this is *highly discouraged*. In general **settings.js** defines low-level options that should not be modified. Note also that the compiler changes some options depending on other settings. For example, ``ASSERTIONS`` is enabled by default, but disabled in optimized builds (``-O1+``).
-
-The small number of options that developers may have cause to change should be modified when the *emcc* tool is invoked. For example, ``EXPORTED_FUNCTIONS``: ::
-
-  ./emcc tests/hello_function.cpp -o function.html -s EXPORTED_FUNCTIONS=_int_sqrt
-
+While it is possible to edit **settings.js** manually, this is *highly
+discouraged*. In general **settings.js** defines low-level options that should
+not be modified. Note also that the compiler changes some options depending on
+other settings. For example, ``ASSERTIONS`` is enabled by default, but disabled
+in optimized builds (``-O1+``).
 
 preamble.js
 ===========
 
-The following advanced APIs are documented in `preamble.js <https://github.com/emscripten-core/emscripten/blob/main/src/preamble.js>`_.
+The following advanced APIs are documented in `preamble.js`_.
 
 .. js:function:: allocate(slab, allocator)
 
-  This is marked as *internal* because it is difficult to use (it has been optimized for multiple syntaxes to save space in generated code). Normally developers should instead allocate memory using ``_malloc()``, initialize it with :js:func:`setValue`, etc., but this function may be useful for advanced developers in certain cases.
+  This is marked as *internal* because it is difficult to use (it has been
+  optimized for multiple syntaxes to save space in generated code). Normally
+  developers should instead allocate memory using ``_malloc()``, initialize it
+  with :js:func:`setValue`, etc., but this function may be useful for advanced
+  developers in certain cases.
 
-  :param slab: An array of data, or a number. If a number, then the size of the block to allocate, in *bytes*.
+  :param slab: An array of data, or a number. If a number, then the size of the
+               block to allocate, in *bytes*.
   :param allocator: How to allocate memory, see ALLOC_*
 
 
 Advanced File System API
 ========================
 
-:ref:`Filesystem-API` covers the public API that will be relevant to most developers. The following functions are only needed for advanced use-cases (for example, writing a new local file system) or legacy file system compatibility.
+:ref:`Filesystem-API` covers the public API that will be relevant to most
+developers. The following functions are only needed for advanced use-cases (for
+example, writing a new local file system) or legacy file system compatibility.
 
 .. js:function::
   FS.hashName(parentid, name)
@@ -106,3 +118,6 @@ There are also a small number of additional :ref:`flag modes <fs-read-and-write-
 - ``xw+``
 - ``xa``
 - ``xa+``
+
+.. _settings.js: https://github.com/emscripten-core/emscripten/blob/main/src/settings.js
+.. _preamble.js: https://github.com/emscripten-core/emscripten/blob/main/src/preamble.js

site/source/docs/api_reference/index.rst

@@ -4,7 +4,8 @@
 API Reference
 =============
 
-This section lists Emscripten's public API, organised by header file. At a very high level it consists of:
+This section lists Emscripten's public API, organised by header file. At a very
+high level it consists of:
 
 - :ref:`emscripten-h`:
   APIs for integrating with the browser environment.
@@ -25,13 +26,15 @@ This section lists Emscripten's public API, organised by header file. At a very
   Enables writing multithreaded programs using a web-like API.
 
 - :ref:`Module`:
-  Global JavaScript object that can be used to control code execution and access exported methods.
+  Global JavaScript object that can be used to control code execution and access
+  exported methods.
 
 - :ref:`val-h`:
   Embind API to support transliteration of JavaScript code to C++.
 
 - :ref:`bind-h`:
-  Embind API for binding C++ functions and classes so that they can be called from JavaScript in a natural way.
+  Embind API for binding C++ functions and classes so that they can be called
+  from JavaScript in a natural way.
 
 - :ref:`trace-h`:
   A tracing API for doing memory usage analysis.
@@ -58,5 +61,3 @@ This section lists Emscripten's public API, organised by header file. At a very
    fiber.h
    wasm_workers
    advanced-apis
-
-