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Describe C99 compliance
shecc implements a subset of C99 suitable for self-hosting and system programming, prioritizing simplicity, educational value, and minimal dependencies over full standard compliance.
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‎COMPLIANCE.md

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# C99 Compliance Status
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shecc implements a subset of C99 suitable for self-hosting and systems programming,
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prioritizing simplicity, educational value, and minimal dependencies over full standard compliance.
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This document tracks compliance gaps and non-standard behaviors.
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## Implemented Features
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### Core Language
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- Basic types: `int`, `char`, `void`, `_Bool`
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- Structures and unions with nested definitions
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- Enumerations with automatic value assignment
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- Function definitions and declarations
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- Arrays (single and multi-dimensional)
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- Pointers and pointer arithmetic (fully C99-compliant)
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- Type definitions (`typedef`)
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### Control Flow
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- `if`/`else` statements
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- `while`, `do-while`, `for` loops
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- `switch`/`case`/`default` statements
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- `break`, `continue`, `return` statements
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### Operators
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- Arithmetic: `+`, `-`, `*`, `/`, `%`
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- Bitwise: `&`, `|`, `^`, `~`, `<<`, `>>`
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- Logical: `&&`, `||`, `!`
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- Relational: `<`, `>`, `<=`, `>=`, `==`, `!=`
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- Assignment: `=`, `+=`, `-=`, `*=`, `/=`, `%=`, `<<=`, `>>=`, `&=`, `|=`, `^=`
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- Increment/decrement: `++`, `--` (prefix and postfix)
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- Conditional: `? :`
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- Member access: `.`, `->`
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- Address/dereference: `&`, `*`
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### Preprocessor (Partial)
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- `#define` for object-like and function-like macros
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- `#ifdef`, `#ifndef`, `#if`, `#elif`, `#else`, `#endif`
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- `#undef` for macro removal
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- `defined()` operator
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- `__VA_ARGS__` for variadic macros
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## Missing Features
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### Storage Classes & Qualifiers
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| Feature | Status | Impact |
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|---------|--------|--------|
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| `static` | Not implemented | No internal linkage or persistent local variables |
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| `extern` | Not implemented | No external linkage declarations |
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| `register` | Not implemented | No register hint optimization |
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| `auto` | Not implemented | Default storage class (implicit) |
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| `const` | Parsed but ignored | No read-only enforcement |
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| `volatile` | Not implemented | No volatile semantics |
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| `restrict` | Not implemented | No pointer aliasing optimization |
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| `inline` | Not implemented | No function inlining |
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### Type System
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| Feature | Status | Notes |
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|---------|--------|-------|
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| `short` | Missing | Only 4-byte integers |
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| `long` | Missing | Only 4-byte integers |
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| `long long` | Missing | No 64-bit integers |
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| `unsigned` | Missing | All integers are signed |
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| `signed` | Missing | Implicit for integers |
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| `float` | Missing | No floating-point support |
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| `double` | Missing | No floating-point support |
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| `long double` | Missing | No floating-point support |
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| Bit-fields | Missing | Cannot pack struct members |
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### Literals & Constants
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| Feature | Status | Current Behavior |
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|---------|--------|-----------------|
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| Integer suffixes (`u`, `l`, `ll`) | Not parsed | All literals are `int` |
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| Wide characters (`L'c'`) | Not supported | Single-byte only |
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| Wide strings (`L"..."`) | Not supported | Single-byte only |
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| Multi-character constants | Not supported | Single character only |
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| Universal characters (`\u`, `\U`) | Not supported | ASCII only |
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| Hex escapes (`\x...`) | Limited | Max 2 hex digits |
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### Preprocessor Gaps
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| Feature | Status | Description |
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|---------|--------|-------------|
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| `#include` | Parsed only | No file inclusion |
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| Token pasting (`##`) | Missing | Cannot concatenate tokens |
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| Stringizing (`#`) | Missing | Cannot convert to string |
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| `__FILE__` | Missing | No file name macro |
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| `__LINE__` | Missing | No line number macro |
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| `__DATE__` | Missing | No compile date |
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| `__TIME__` | Missing | No compile time |
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| `__STDC__` | Missing | No standard compliance indicator |
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| `#pragma` | Ignored | Accepted but no effect |
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### Advanced Features
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| Feature | Status | Description |
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|---------|--------|-------------|
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| `goto` and labels | Missing | No arbitrary jumps |
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| Designated initializers | Missing | No `.field = value` syntax |
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| Compound literals | Partial | Limited support |
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| Flexible array members | Missing | No `[]` at struct end |
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| Variable-length arrays | Missing | No runtime-sized arrays |
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| `_Complex` | Missing | No complex numbers |
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| `_Imaginary` | Missing | No imaginary numbers |
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| `_Static_assert` | Missing | No compile-time assertions |
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| `_Alignof` | Missing | No alignment queries |
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| `_Alignas` | Missing | No alignment specification |
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| `_Generic` | Missing | No generic selection |
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## Non-Standard Behaviors
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### GNU Extensions
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- Binary literals: `0b101010`
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- Escape sequence: `\e` for ESC character
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- `void*` arithmetic (treated as `char*`)
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- `sizeof(void)` returns 0 (should be error)
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### Implementation-Specific
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- Array compound literals in scalar context use first element
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- String literals are modifiable (stored in `.data`, not `.rodata`)
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- No strict aliasing rules
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- Left-to-right evaluation order (not always guaranteed in C99)

‎CONTRIBUTING.md

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Visit our [Issues page on GitHub](https://github.com/sysprog21/shecc/issues) to search and submit.
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## Language Compliance
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Before contributing new language features or modifications to the compiler frontend,
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please review [COMPLIANCE.md](COMPLIANCE.md) to understand shecc's current C99 compliance status,
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supported features, and known limitations. This document helps ensure that contributions
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align with the project's subset implementation philosophy.
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## Coding Convention
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Contributions from developers across corporations, academia, and individuals are welcome.

‎README.md

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} }
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```
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## C99 Compliance
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shecc implements a subset of C99 suitable for self-hosting and systems programming.
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For detailed information about supported features, missing functionality, and non-standard behaviors,
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see [COMPLIANCE.md](COMPLIANCE.md).
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## Known Issues
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2. Full `<stdarg.h>` support is not available. Variadic functions work via direct pointer arithmetic.

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