Support short and long integer types

[jserv]

Description

shecc currently only supports int and char integer types. Adding support for short and long would improve C99 compliance and enable compilation of more real-world C code.

Current Behavior

short s = 32767;     // Error: "invalid type specifier"
long l = 2147483647; // Error: "invalid type specifier"
unsigned short us;   // Error: not supported

Expected Behavior

Support standard C integer type hierarchy:

• short / short int (typically 16-bit)
• long / long int (32-bit or 64-bit)
• long long / long long int (at least 64-bit)
• Combined with unsigned modifier

Implementation Requirements

1. Lexer Changes

• Recognize short and long keywords
• Handle type specifier combinations (short int, long int, etc.)

2. Type System

• Add new base types to enum
• Define size constants for each type
• Handle type promotion rules

3. Code Generation

• Proper sign/zero extension for different sizes
• Correct load/store instructions for each size
• Type casting between different integer sizes

Test Cases

// Basic declarations
short s1 = 100;
long l1 = 1000000;
long long ll1 = 1000000000000LL;

// Type promotion
int i = s1;        // short to int
long l = i;        // int to long
short s2 = (short)l1;  // explicit cast

// Arithmetic
short result = s1 + 10;
long product = l1 * 2;

// Arrays and pointers
short arr[10];
long *ptr = &l1;

Benefits

• Better C99 standard compliance
• Support for more existing C code
• Proper handling of different data sizes
• Foundation for full integer type system

[jserv]

Close via #306