The compilation of incomplete C code can be useful in a variety of scenarios: debugging a snippet retrieved from a bug-tracking tool; running an static analysis on only part of a program; supporting code-completion within an IDE; during cross-platform development when a header is incompatible; or to generate data-structures straight out of algorithm implementations.
Psyche-c
is a compiler for incomplete C code being developed in
our lab
. It receives as an input a snippet[1]. From it, psyche-c produces a header file that, once #included into the original program, leads to compilable code[2].
To complete the missing parts of programs, psyche-c solves several challenges. The first ones appear during parsing, which in C requires, not only syntax, but also semantic information. Yet, the really cool challenges appear during type inference. Is 0 an integer or the null pointer? How to account for const/volatile in implicit conversions (particularly through poitners)? What about variadic functions? And the subtyping relation involving void*? Psyche-c is still under research, but you can give it a try. Its source is available at
https://github.com/ltcmelo/psychec
.
[1] In this online version, if an expanded macro is present, then it must conform to the C grammar (i.e. be syntactically valid).
[2] We don't generate function definitions, only declarations. Therefore, linking may not be possible.
For a wrapper around psyche-c that integrates with your host compiler, check
Cnippet
.
A paper that describes psyche-c's internals has been accepted to to
POPL 2018
(
Slides
/
Video
).
- To preprocess your code you can run GCC/Clang with `gcc -E -P'.
- Ensure the code is valid: start with a compilable program, then gradually strip it off.
/* The code commented-out bellow illustrates the missing parts of a program. #define FAIL_MACRO(VAL) ... typedef ... List; typedef ... Result; int analyse(List list) { ... } List make() { ... } */ Result generate(double val) { List list; /* No declaration of `List' available. */ list = 0; /* `List' is a pointer or an integral. */ list = make(); /* Function `make' must return a `List'. */ list->data = val; /* List has a member of type `double'. */ list->next = list; /* And it's a recursive type. */ if (analyse(list)) /* Function `analyse' must take a `List'. */ return "OK"; /* We got `generate's return type. */ return FAIL_MACRO(1); /* Unexpanded macro, but syntactically valid. */ }
Check if the result is compilable with:
gcc
clang
