c2go - Convert C to Go

This is a subproject of the Go+ project. Its goal is converting any C project into Go without any human intervention and keeping performance close to C.

• Make it passed. Stage: Done Almost. We have compiled libc (in progress) and sqlite3 (done).
• Make it correct. Stage: Doing. We ported libc-test to test c2go and libc. Coverage:
• Make it fast. Stage: Planning.

How to run examples?

Run an example:

• Build c2go tools: go install -v ./...
• Go testdata/xxx directory, and run c2go .

Run/Test multiple examples:

• Run examples: c2go ./...
• Test examples: c2go -test ./...

How c2go is used in Go+

Here is an example to show how Go+ interacts with C.

import "C"

C.printf C"Hello, c2go!\n"
C.fprintf C.stderr, C"Hi, %7.1f\n", 3.14

Here we use import "C" to import libc. It's an abbreviation for import "C/github.com/goplus/libc". It is equivalent to the following code:

import "C/github.com/goplus/libc"

C.printf C"Hello, c2go!\n"
C.fprintf C.stderr, C"Hi, %7.1f\n", 3.14

In this example we call two C standard functions printf and fprintf, passing a C variable stderr and two C strings in the form of C"xxx" (a Go+ syntax to represent C style strings).

Run gop run . to see the output of this example:

Hello, c2go!
Hi,     3.1

What's our plan?

• First, support most of the syntax of C. Stage: Done Almost, see supported C syntax.
• Second, compile sqlite3 to fix c2go bugs and get list of its dependent C standard libary fuctions. Stage: Done, see github.com/goplus/sqlite and its dependent fuctions.
• Third, support most of C standard library functions (especially that used by sqlite3), and can import them by Go+. Stage: Doing, see detailed progress here.
• Last, support all custom libraries, especially those well-known open source libraries. Stage: Planning.

Tested Platform

• MacOS: 11.x
• Linux: ubuntu-20.04 (temporarily skip testdata/qsort)
• Windows

Supported C syntax

Data structures

• Void: void
• Boolean: _Bool, bool
• Integer: [signed/unsigned] [short/long/long long] int
• Enum: enum
• Float: float, double, long double
• Character: [signed/unsigned] char
• Wide Character: wchar_t
• Large Integer: [signed/unsigned] __int128
• Complex: _Complex float/double/long double
• Typedef: typedef
• Pointer: *T, T[]
• Array: T[N], T[]
• Array Pointer: T(*)[N]
• Function Pointer: T (*)(T1, T2, ...)
• Struct: struct
• Union: union
• BitField: intType :N

Operators

• Arithmetic: a+b, a-b, a*b, a/b, a%b, -a, +a
• Increment/Decrement: a++, a--, ++a, --a
• Comparison: a<b, a<=b, a>b, a>=b, a==b, a!=b
• Logical: a&&b, a||b, !a
• Bitwise: a|b, a&b, a^b, ~a, a<<n, a>>n
• Pointer Arithmetic: p+n, p-n, p-q, p++, p--
• Assignment: =
• Operator Assignment: a<op>=b
• BitField Assignment: =
• BitField Operator Assignment: a<op>=b
• Struct/Union/BitField Member: a.b
• Array Member: a[n]
• Pointer Member: &a, *p, p[n], n[p], p->b
• Comma: a,b
• Ternary Conditional: cond?a:b
• Function Call: f(a1, a2, ...)
• Conversion: (T)a
• Sizeof: sizeof(T), sizeof(a)
• Offsetof: __builtin_offsetof(T, member)

Literals

• Boolean, Integer
• Float, Complex Imaginary
• Character, String
• Array: (T[]){ expr1, expr2, ... }
• Array Pointer: &(T[]){ expr1, expr2, ... }
• Struct: struct T{ expr1, expr2, ... }

Initialization

• Basic: T a = expr
• Array: T a[] = { expr1, expr2, ... }, T a[N] = { expr1, expr2, ... }
• Struct: struct T a = { expr1, expr2, ... }, struct T a = { .a = expr1, .b = expr2, ... }
• Union: union T a = { expr }, union T a = { .a = expr }
• Array in Struct: struct { T a[N]; ... } v = { { expr1, expr2, ... }, ... }, struct { T a[N]; ... } v = { { [0].a = expr1, [1].a = expr2, ... }, ... }

Control structures

• If: if (cond) stmt1 [else stmt2]
• Switch: switch (tag) { case expr1: stmt1 case expr2: stmt2 default: stmtN }
• For: for (init; cond; post) stmt
• While: while (cond) stmt
• Do While: do stmt while (cond)
• Break/Continue: break, continue
• Goto: goto label

Functions

• Parameters
• Variadic Parameters
• Variadic Parameter Access
• Return