a1liu / tci

Teaching C Interpreter

Teaching C Interpreter

The goals of this compiler are:

1. Provide better error messages for new programmers
2. Make debugging C programs easier

Rationale

Learning C is hard. Students have to navigate pointers, segmentation faults, and bit manipulation, all while working without garbage collection, usually for the first time. This interpreter aims to address this problem by giving better error messages and more runtime diagnostic tools.

Features

• Better debug information
  • Stack traces on segmentation fault
• Harder errors: the following all cause a segmentation fault
  • use-after-free
  • buffer overflow
  • double free
  • out of memory
  • stack overflow
  • calling string functions with a string that isn't null-terminated

Todo

Lots of stuff left to do still.

Compiler

• Const
• Enums
• Designated initializers
• full support for #if
• Better macro debug messages
• Better parsing error messages
• Hardening against invalid input
• Unified error system

Runtime Environment

• Leak detection: manual memory management is hard sometimes
• Processes and threads: students often learn multithreading paradigms in C
• Program arguments && Standard input - good functionality to have
• unistd.h: because sometimes professors be like that
• time.h: because sometimes you gotta do that
• Variable/type information at runtime: allows student to use TCI as a debugger
• Full kernel replayability: go backwards in time when using TCI as debugger

User Interface

• Working file system explorer
• Runtime file explorer
• Terminal emulator (without shell)
• Service worker for caching stuff locally
• Github Issue/Bug-fix-request button
• User interface for runtime/compiler options

Restrictions and Incompatibilities

• Implicit types on functions will never be supported
• Implicit function declarations will never be supported

Credit

• TCI uses an error renderer plagiarised from codespan-reporting to make error messages.
• TCI uses a parser plagiarized from lang-c to handle parsing the C language

tci's Issues

Basic Frontend with File Explorer

A Basic front end with a file explorer so that the user can pick which files to compile

Editor bugs

Editor is generally buggy, with highlighting being off and scrolling through large files being impossible

Pressing enter in editor causes terminal to do a new line

when user not focused on the terminal do we shouldn't be handling user input. We just need to set up some handlers to make sure this doesn't happen

Frontend does not render runtime errors

Breakpoints

We want to be able to insert a breakpoint at any point in the program.

Basic Debugger

Basic functionality to step forwards in code bit by bit using buttons.

Advanced Symbol Table Info at Runtime

Advanced symbol table information, like what variable is what type or where variables are located, is not available to the programmer at runtime.

Operator Parsing

We don't parse very many operators right now.

Reduce Allocations and Copies made in Assembler

The assembler doesn't need to recursively allocate a new Vec for each call to translate_block.

Full Program Replayability

We have memory replayability right now, but we want full program replayability.

Marker not being deleted during file switch

• File switch through button click doesn't remove marker during replay