Personal GCC plugin collection
==============================


Compile time string hashing
---------------------------

The problem:
Compile time computations are pretty new feature for C++ and does not supported
for plain C. The *constexpr* qualifier/keyword does not give any guaranties to user
that computations will be performed at the compile time. Actually this keyword 
informs user that computations _may be performed_ at the compile time, or may be
not performed because a lot of non-trivial reasons. To solve this problem C++20
introduces *consteval* and *constinit* keywords. From the plain C side there is
none changes to support it.
So the compile time computing hash values for literal strings is stay messy nowadays.

The idea:
We can filter C/C++ sources right after preprocessing is done and substitute any
hash function invocation from literal strings with its actual hash value.
It implies to handle sources explicitely in three phases - preprocessing, filtering,
and compilation, so it is not such effective, as the single call for compiler.

The solution:
We can hack gcc and introduce custom filtering pass with external plugin.


Requirements
------------

- GNU make 4.2
- gcc 8.3.x
- g++ 8.3.x
- Linux or UNIX-like OS


Compiling
---------

Perform the followed command to build gcc plugin and test sample:
$ make all

Note:
The versions form requirements section are tested. Compiling may fail (or may be success)
for other toolchain versions.

Compiling for MinGW or with MinGW on Windows is possible, but not supported
currently.


How to run gcc plugin
---------------------

-iplugindir=</path/to/plugins/directory>
-fplugin=<path/to/plugin.ext>
-fplugin-arg-name-<key1>[=value1]

Query for default plugins directory:
$ gcc -print-file-name=plugin


vim: ts=4:tw=78:noet