feat(rivet+rivetc): implement basic comptime if (#56)

The comptime `if` feature is added, and the previously used preprocessor is removed.

This comptime `if` is basic, and has access to flags defined with the `-D` option and 
symbols that already worked in the preprocessor.

README.md

@@ -55,8 +55,6 @@ quality.
 * **Not NULL values by default**: This is only possible with option types (`?T`) and `none`.
 * **Easy error handling**: With result types, `func my_func() -> !T { ... }`,
     `throw` and `catch`.
-* **A basic preprocessor**: `if`, `else_if`, `else` and `endif` for optional code using
-    flags (`-D my_flag`).
 * **Immutable values**: Variables and fields are immutable by default.
     structs have internal immutability.
 * **Polymorphism**: Traits, Embedded Structs and Tagged Enums are supported.
@@ -88,4 +86,4 @@ successfully.
 Only linux is supported for now. Windows is not well supported, and macOS is not supported
 yet. Any help to provide full support for both Windows and macOS is welcome.
 
-Read [CONTRIBUTING](CONTRIBUTING.md) to get more information.
+Read [CONTRIBUTING](CONTRIBUTING.md) to get more information.

lib/c/src/errno.c.ri

@@ -1,5 +1,5 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
 import c/libc;
@@ -16,13 +16,11 @@ pub struct ErrnoError < Throwable {
 
 #[inline]
 pub func errno() -> int32 {
-    return unsafe {
-#if _LINUX_
-        libc.__errno_location()?.*
-#else
-        libc._errno().*
-#endif
-    };
+    comptime if _LINUX_ {
+        return unsafe { libc.__errno_location()?.* };
+    } else {
+        return unsafe { libc._errno().* };
+    }
 }
 
 #[inline]

lib/c/src/libc/errno.ri

@@ -1,24 +1,24 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
-#if _LINUX_
-extern (C) {
-    pub func __errno_location() -> ?&mut int32;
+comptime if _LINUX_ {
+    extern (C) {
+        pub func __errno_location() -> ?&mut int32;
+    }
+
+    pub const EDOM := 33;
+    pub const EILSEQ := 84;
+    pub const ERANGE := 34;
 }
 
-pub const EDOM := 33;
-pub const EILSEQ := 84;
-pub const ERANGE := 34;
-#endif
+comptime if _WINDOWS_ {
+    extern (C) {
+        #[dllimport]
+        pub func _errno() -> &mut int32;
+    }
 
-#if _WINDOWS_
-extern (C) {
-    [dllimport]
-    pub func _errno() &mut int32;
+    pub const EDOM := 33;
+    pub const EILSEQ := 42;
+    pub const ERANGE := 34;
 }
-
-pub const EDOM := 33;
-pub const EILSEQ := 42;
-pub const ERANGE := 34;
-#endif

lib/c/src/libc/signal.ri

@@ -1,5 +1,5 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
 // TODO(StunxFS): replace the argument type of `SignalHandler` from
@@ -9,7 +9,7 @@ import ../ctypes.{ pid_t, uid_t };
 
 pub alias SignalHandler := func(int32, &mut siginfo_t, rawptr);
 
-#if _LINUX_
+comptime if _LINUX_ {
     pub const SA_ONSTACK := 0x08000000;
     pub const SA_SIGINFO := 0x00000004;
     pub const SA_NOCLDWAIT := 0x00000002;
@@ -50,7 +50,7 @@ pub alias SignalHandler := func(int32, &mut siginfo_t, rawptr);
     pub const SEGV_ACCERR := 0x2;
 
     pub struct sigset_t {
-        pub __val: [#if _X86_ 32 #else 16 #endif]uint32;
+        pub __val: [comptime if _X86_ { 32 } else { 16 }]uint32;
     }
 
     pub struct sigval {
@@ -76,21 +76,21 @@ pub alias SignalHandler := func(int32, &mut siginfo_t, rawptr);
         pub sa_flags: int32;
         pub sa_restorer: func();
     }
-#else_if _WINDOWS_
+} else if _WINDOWS_ {
     pub const SIGABRT := 22;
     pub const SIGFPE := 8;
     pub const SIGILL := 4;
     pub const SIGINT := 2;
     pub const SIGSEGV := 11;
     pub const SIGTERM := 15;
-#else
-    #error cannot define values for signals in this operating system, please report the issue
-#endif
+} else {
+    // TODO: error cannot define values for signals in this operating system, please report the issue
+}
 
 extern (C) {
-#if _LINUX_
-    pub func sigaction(signum: int32, act: ?&sigaction_t, old_act: ?&mut sigaction_t) -> int32;
-#endif
+    comptime if _LINUX_ {
+        pub func sigaction(signum: int32, act: ?&sigaction_t, old_act: ?&mut sigaction_t) -> int32;
+    }
     pub func signal(sig: int32, handler: SignalHandler) -> ?SignalHandler;
     pub func raise(sig: int32) -> int32;
 }

lib/c/src/libc/stat.ri

@@ -1,31 +1,31 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
 import c/ctypes.*;
 
-#if _AMD64_
-// The `stat` definition used by the Linux kernel.
-pub struct Stat {
-    pub dev: dev_t;
-    pub ino: ino_t;
-    pub nlink: uint;
+comptime if _AMD64_ {
+    // The `stat` definition used by the Linux kernel.
+    pub struct Stat {
+        pub dev: dev_t;
+        pub ino: ino_t;
+        pub nlink: uint;
 
-    pub mode: uint32;
-    pub uid: uid_t;
-    pub gid: gid_t;
-    __pad0: uint32;
-    pub rdev: dev_t;
-    pub size: off_t;
-    pub blksize: int;
-    pub blocks: int64;
+        pub mode: uint32;
+        pub uid: uid_t;
+        pub gid: gid_t;
+        __pad0: uint32;
+        pub rdev: dev_t;
+        pub size: off_t;
+        pub blksize: int;
+        pub blocks: int64;
 
-    pub atim: timespec;
-    pub mtim: timespec;
-    pub ctim: timespec;
-    __unused: [3]int;
+        pub atim: timespec;
+        pub mtim: timespec;
+        pub ctim: timespec;
+        __unused: [3]int;
+    }
 }
-#endif
 
 extern (C) {
     pub func stat(__file: [&]uint8, __buf: &mut Stat) -> int32;

lib/c/src/libc/stdio.ri

@@ -1,5 +1,5 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
 import c/ctypes.*;
@@ -35,7 +35,7 @@ pub const O_CLOEXEC := 0x80000;
 
 pub struct FILE;
 
-#if _LINUX_
+comptime if _LINUX_ {
     extern (C) {
         pub var stdin: &mut FILE;
         pub var stdout: &mut FILE;
@@ -62,11 +62,11 @@ pub struct FILE;
 	pub const SEEK_END := 2;
 
 	pub const TMP_MAX := 308915776;
-#endif
+}
 
-#if _WINDOWS_
+comptime if _WINDOWS_ {
     extern (C) {
-        func __acrt_iob_fn(index: uint32) &mut FILE;
+        func __acrt_iob_fn(index: uint32) -> &mut FILE;
     }
 
     pub alias fpos_t := int64;
@@ -89,7 +89,7 @@ pub struct FILE;
     pub var stdin: &mut FILE := unsafe { __acrt_iob_fn(0) };
     pub var stdout: &mut FILE := unsafe { __acrt_iob_fn(1) };
     pub var stderr: &mut FILE := unsafe { __acrt_iob_fn(2) };
-#endif
+}
 
 extern (C) {
     pub func fopen(path: [&]uint8, mode: [&]uint8) -> ?&mut FILE;

lib/c/src/libc/stdlib.ri

@@ -1,14 +1,14 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
-#if _LINUX_
+comptime if _LINUX_ {
     pub const RAND_MAX := 0x7fffffff;
-#else_if _WINDOWS_
+} else if _WINDOWS_ {
     pub const RAND_MAX := 0x7fff;
-#else
-    #error cannot define RAND_MAX in this operating system, please report the issue
-#endif
+} else {
+     // TODO: error cannot define RAND_MAX in this operating system, please report the issue
+}
 
 extern (C) {
     pub func rand() -> int32;

lib/c/src/libc/unistd.ri

@@ -1,5 +1,5 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
 extern (C) {
@@ -21,7 +21,7 @@ extern (C) {
 
     pub func readlink(path: [&]uint8, buf: [&]uint8, size: uint) -> int;
 
-#if _LINUX_
-    pub func get_nprocs() -> int32;
-#endif
+    comptime if _LINUX_ {
+        pub func get_nprocs() -> int32;
+    }
 }

lib/c/src/wyhash.ri

@@ -1,5 +1,5 @@
-// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this 
-// source code is governed by an MIT license that can be found in the LICENSE 
+// Copyright (C) 2023-present Jose Mendoza - All rights reserved. Use of this
+// source code is governed by an MIT license that can be found in the LICENSE
 // file.
 
 #![compile_c_source("../thirdparty/wyhash/wyhash.c")]
@@ -20,7 +20,7 @@ extern (C) {
     func wy2u01(r: uint64) -> float64;
     func wy2gau(r: uint64) -> float64;
 
-#if !WYHASH_32BIT_MUM
-    func wy2u0k(r: uint64, k: uint64) -> uint64;
-#endif
+    comptime if !WYHASH_32BIT_MUM {
+        func wy2u0k(r: uint64, k: uint64) -> uint64;
+    }
 }