fallback: extract into crate

For faster incremental builds and to enable subsequent extraction.

Closes #12183

Cargo.lock

@@ -161,6 +161,7 @@ dependencies = [
  "fish-build-helper",
  "fish-build-man-pages",
  "fish-common",
+ "fish-fallback",
  "fish-gettext",
  "fish-gettext-extraction",
  "fish-gettext-mo-file-parser",
@@ -205,6 +206,25 @@ dependencies = [
 [[package]]
 name = "fish-common"
 version = "0.0.0"
+dependencies = [
+ "libc",
+ "nix",
+ "once_cell",
+]
+
+[[package]]
+name = "fish-fallback"
+version = "0.0.0"
+dependencies = [
+ "fish-build-helper",
+ "fish-common",
+ "fish-wchar",
+ "fish-widecharwidth",
+ "libc",
+ "once_cell",
+ "rsconf",
+ "widestring",
+]
 
 [[package]]
 name = "fish-gettext"

Cargo.toml

@@ -18,6 +18,7 @@ errno = "0.3.0"
 fish-build-helper = { path = "crates/build-helper" }
 fish-build-man-pages = { path = "crates/build-man-pages" }
 fish-common = { path = "crates/common" }
+fish-fallback = { path = "crates/fallback" }
 fish-gettext = { path = "crates/gettext" }
 fish-gettext-extraction = { path = "crates/gettext-extraction" }
 fish-gettext-maps = { path = "crates/gettext-maps" }
@@ -93,6 +94,7 @@ errno.workspace = true
 fish-build-helper.workspace = true
 fish-build-man-pages = { workspace = true, optional = true }
 fish-common.workspace = true
+fish-fallback.workspace = true
 fish-gettext = { workspace = true, optional = true }
 fish-gettext-extraction = { workspace = true, optional = true }
 fish-printf.workspace = true

crates/common/Cargo.toml

@@ -6,5 +6,10 @@ version = "0.0.0"
 repository.workspace = true
 license.workspace = true
 
+[dependencies]
+libc.workspace = true
+nix.workspace = true
+once_cell.workspace = true
+
 [lints]
 workspace = true

crates/common/src/lib.rs

@@ -1,3 +1,8 @@
+use libc::STDIN_FILENO;
+use once_cell::sync::OnceCell;
+use std::env;
+use std::os::unix::ffi::OsStrExt;
+
 // These are in the Unicode private-use range. We really shouldn't use this
 // range but have little choice in the matter given how our lexer/parser works.
 // We can't use non-characters for these two ranges because there are only 66 of
@@ -26,3 +31,30 @@ pub fn subslice_position<T: Eq>(a: &[T], b: &[T]) -> Option<usize> {
     }
     a.windows(b.len()).position(|aw| aw == b)
 }
+
+/// This function attempts to distinguish between a console session (at the actual login vty) and a
+/// session within a terminal emulator inside a desktop environment or over SSH. Unfortunately
+/// there are few values of $TERM that we can interpret as being exclusively console sessions, and
+/// most common operating systems do not use them. The value is cached for the duration of the fish
+/// session. We err on the side of assuming it's not a console session. This approach isn't
+/// bullet-proof and that's OK.
+pub fn is_console_session() -> bool {
+    static IS_CONSOLE_SESSION: OnceCell<bool> = OnceCell::new();
+    // TODO(terminal-workaround)
+    *IS_CONSOLE_SESSION.get_or_init(|| {
+        nix::unistd::ttyname(unsafe { std::os::fd::BorrowedFd::borrow_raw(STDIN_FILENO) })
+            .is_ok_and(|buf| {
+                // Check if the tty matches /dev/(console|dcons|tty[uv\d])
+                let is_console_tty = match buf.as_os_str().as_bytes() {
+                    b"/dev/console" => true,
+                    b"/dev/dcons" => true,
+                    bytes => bytes.strip_prefix(b"/dev/tty").is_some_and(|rest| {
+                        matches!(rest.first(), Some(b'u' | b'v' | b'0'..=b'9'))
+                    }),
+                };
+
+                // and that $TERM is simple, e.g. `xterm` or `vt100`, not `xterm-something` or `sun-color`.
+                is_console_tty && env::var_os("TERM").is_none_or(|t| !t.as_bytes().contains(&b'-'))
+            })
+    })
+}

crates/fallback/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "fish-fallback"
+edition.workspace = true
+rust-version.workspace = true
+version = "0.0.0"
+repository.workspace = true
+license.workspace = true
+
+[dependencies]
+fish-common.workspace = true
+fish-wchar.workspace = true
+fish-widecharwidth.workspace = true
+libc.workspace = true
+once_cell.workspace = true
+widestring.workspace = true
+
+[build-dependencies]
+fish-build-helper.workspace = true
+rsconf.workspace = true
+
+[lints]
+workspace = true

crates/fallback/build.rs

@@ -0,0 +1,5 @@
+use fish_build_helper::target_os_is_cygwin;
+
+fn main() {
+    rsconf::declare_cfg("cygwin", target_os_is_cygwin())
+}

crates/fallback/src/lib.rs

@@ -3,7 +3,7 @@
 //!
 //! Many of these functions are more or less broken and incomplete.
 
-use crate::wchar::prelude::*;
+use fish_wchar::prelude::*;
 use fish_widecharwidth::{WcLookupTable, WcWidth};
 use once_cell::sync::Lazy;
 use std::cmp;
@@ -46,7 +46,7 @@ pub fn fish_wcwidth(c: char) -> isize {
     // in the console session, but knows nothing about the capabilities of other terminal emulators
     // or ttys. Use it from the start only if we are logged in to the physical console.
     #[cfg(not(cygwin))]
-    if crate::common::is_console_session() {
+    if fish_common::is_console_session() {
         return wcwidth(c);
     }
 
@@ -165,7 +165,7 @@ pub fn new(mut chars: std::iter::Map<CharsUtf32<'a>, Canonicalize>) -> Self {
 #[cfg(test)]
 mod tests {
     use super::wcscasecmp;
-    use crate::wchar::prelude::*;
+    use fish_wchar::prelude::*;
     use std::cmp::Ordering;
 
     #[test]

src/builtins/string/pad.rs

@@ -1,5 +1,5 @@
 use super::*;
-use crate::fallback::fish_wcwidth;
+use fish_fallback::fish_wcwidth;
 
 pub struct Pad {
     char_to_pad: char,

src/builtins/ulimit.rs

@@ -5,8 +5,8 @@
 use nix::sys::resource::Resource as ResourceEnum;
 use once_cell::sync::Lazy;
 
-use crate::fallback::{fish_wcswidth, wcscasecmp};
 use crate::wutil::perror;
+use fish_fallback::{fish_wcswidth, wcscasecmp};
 
 use super::prelude::*;
 

src/common.rs

@@ -4,7 +4,6 @@
     BRACE_BEGIN, BRACE_END, BRACE_SEP, BRACE_SPACE, HOME_DIRECTORY, INTERNAL_SEPARATOR,
     PROCESS_EXPAND_SELF, PROCESS_EXPAND_SELF_STR, VARIABLE_EXPAND, VARIABLE_EXPAND_SINGLE,
 };
-use crate::fallback::fish_wcwidth;
 use crate::future_feature_flags::{FeatureFlag, feature_test};
 use crate::global_safety::AtomicRef;
 use crate::global_safety::RelaxedAtomicBool;
@@ -17,7 +16,8 @@
 use crate::wildcard::{ANY_CHAR, ANY_STRING, ANY_STRING_RECURSIVE};
 use crate::wutil::fish_iswalnum;
 use bitflags::bitflags;
-use fish_common::{ENCODE_DIRECT_END, char_offset, subslice_position};
+use fish_common::{ENCODE_DIRECT_END, char_offset, is_console_session, subslice_position};
+use fish_fallback::fish_wcwidth;
 use fish_wchar::{decode_byte_from_char, encode_byte_to_char};
 use libc::{SIG_IGN, SIGTTOU, STDIN_FILENO};
 use once_cell::sync::OnceCell;
@@ -1796,33 +1796,6 @@ impl<T, F: FnOnce(T)> ScopeGuarding for ScopeGuard<T, F> {}
 pub const fn assert_send<T: Send>() {}
 pub const fn assert_sync<T: Sync>() {}
 
-/// This function attempts to distinguish between a console session (at the actual login vty) and a
-/// session within a terminal emulator inside a desktop environment or over SSH. Unfortunately
-/// there are few values of $TERM that we can interpret as being exclusively console sessions, and
-/// most common operating systems do not use them. The value is cached for the duration of the fish
-/// session. We err on the side of assuming it's not a console session. This approach isn't
-/// bullet-proof and that's OK.
-pub fn is_console_session() -> bool {
-    static IS_CONSOLE_SESSION: OnceCell<bool> = OnceCell::new();
-    // TODO(terminal-workaround)
-    *IS_CONSOLE_SESSION.get_or_init(|| {
-        nix::unistd::ttyname(unsafe { std::os::fd::BorrowedFd::borrow_raw(STDIN_FILENO) })
-            .is_ok_and(|buf| {
-                // Check if the tty matches /dev/(console|dcons|tty[uv\d])
-                let is_console_tty = match buf.as_os_str().as_bytes() {
-                    b"/dev/console" => true,
-                    b"/dev/dcons" => true,
-                    bytes => bytes.strip_prefix(b"/dev/tty").is_some_and(|rest| {
-                        matches!(rest.first(), Some(b'u' | b'v' | b'0'..=b'9'))
-                    }),
-                };
-
-                // and that $TERM is simple, e.g. `xterm` or `vt100`, not `xterm-something` or `sun-color`.
-                is_console_tty && env::var_os("TERM").is_none_or(|t| !t.as_bytes().contains(&b'-'))
-            })
-    })
-}
-
 /// Asserts that a slice is alphabetically sorted by a <code>&[wstr]</code> `name` field.
 ///
 /// Mainly useful for static asserts/const eval.

src/env_dispatch.rs

@@ -155,9 +155,9 @@ fn handle_timezone(var_name: &wstr, vars: &EnvStack) {
     }
 }
 
-/// Update the value of [`FISH_EMOJI_WIDTH`](crate::fallback::FISH_EMOJI_WIDTH).
+/// Update the value of [`FISH_EMOJI_WIDTH`](fish_fallback::FISH_EMOJI_WIDTH).
 pub fn guess_emoji_width(vars: &EnvStack) {
-    use crate::fallback::FISH_EMOJI_WIDTH;
+    use fish_fallback::FISH_EMOJI_WIDTH;
 
     if let Some(width_str) = vars.get(L!("fish_emoji_width")) {
         // The only valid values are 1 or 2; we default to 1 if it was an invalid int.
@@ -199,7 +199,7 @@ pub fn guess_emoji_width(vars: &EnvStack) {
         // Default to whatever the system's wcwidth gives for U+1F603, but only if it's at least
         // 1 and at most 2.
         #[cfg(not(cygwin))]
-        let width = crate::fallback::wcwidth('😃').clamp(1, 2);
+        let width = fish_fallback::wcwidth('😃').clamp(1, 2);
         #[cfg(cygwin)]
         let width = 2_isize;
         FISH_EMOJI_WIDTH.store(width, Ordering::Relaxed);
@@ -238,7 +238,7 @@ fn handle_change_ambiguous_width(vars: &EnvStack) {
         .unwrap_or(1)
         // Clamp in case of negative values.
         .max(0) as isize;
-    crate::fallback::FISH_AMBIGUOUS_WIDTH.store(new_width, Ordering::Relaxed);
+    fish_fallback::FISH_AMBIGUOUS_WIDTH.store(new_width, Ordering::Relaxed);
 }
 
 fn handle_term_size_change(vars: &EnvStack) {

src/key.rs

@@ -2,13 +2,13 @@
 
 use crate::{
     common::{EscapeFlags, EscapeStringStyle, escape_string},
-    fallback::fish_wcwidth,
     flog::FloggableDebug,
     future_feature_flags::{FeatureFlag, test as feature_test},
     reader::safe_get_terminal_mode_on_startup,
     wchar::prelude::*,
     wutil::fish_wcstoul,
 };
+use fish_fallback::fish_wcwidth;
 use fish_wchar::decode_byte_from_char;
 
 pub(crate) const Backspace: char = '\u{F500}'; // below ENCODE_DIRECT_BASE

src/lib.rs

@@ -22,7 +22,6 @@
 pub mod event;
 pub mod exec;
 pub mod expand;
-pub mod fallback;
 pub mod fd_monitor;
 pub mod fd_readable_set;
 pub mod fds;

src/parse_constants.rs

@@ -1,8 +1,8 @@
 //! Constants used in the programmatic representation of fish code.
 
-use crate::fallback::{fish_wcswidth, fish_wcwidth};
 use crate::wchar::prelude::*;
 use bitflags::bitflags;
+use fish_fallback::{fish_wcswidth, fish_wcwidth};
 
 pub type SourceOffset = u32;
 

src/reader/reader.rs

@@ -71,7 +71,6 @@
 use crate::exec::exec_subshell;
 use crate::expand::expand_one;
 use crate::expand::{ExpandFlags, ExpandResultCode, expand_string, expand_tilde};
-use crate::fallback::fish_wcwidth;
 use crate::fd_readable_set::poll_fd_readable;
 use crate::fds::{AutoCloseFd, make_fd_blocking, wopen_cloexec};
 use crate::flog::{flog, flogf};
@@ -158,6 +157,7 @@
 use crate::wildcard::wildcard_has;
 use crate::wutil::{fstat, perror, write_to_fd, wstat};
 use crate::{abbrs, event, function};
+use fish_fallback::fish_wcwidth;
 
 /// A description of where fish is in the process of exiting.
 #[repr(u8)]

src/screen.rs

@@ -26,7 +26,6 @@
     has_working_tty_timestamps, shell_modes, wcs2bytes, write_loop,
 };
 use crate::env::Environment;
-use crate::fallback::fish_wcwidth;
 use crate::flog::{flog, flogf};
 use crate::global_safety::RelaxedAtomicBool;
 use crate::highlight::{HighlightColorResolver, HighlightRole, HighlightSpec};
@@ -39,6 +38,7 @@
 use crate::wchar::prelude::*;
 use crate::wcstringutil::{fish_wcwidth_visible, string_prefixes_string};
 use crate::wutil::fstat;
+use fish_fallback::fish_wcwidth;
 
 #[derive(Copy, Clone, Default)]
 pub enum CharOffset {

src/wcstringutil.rs

@@ -1,8 +1,8 @@
 //! Helper functions for working with wcstring.
 
 use crate::common::{get_ellipsis_char, get_ellipsis_str};
-use crate::fallback::{fish_wcwidth, wcscasecmp, wcscasecmp_fuzzy};
 use crate::wchar::prelude::*;
+use fish_fallback::{fish_wcwidth, wcscasecmp, wcscasecmp_fuzzy};
 use fish_wchar::decode_byte_from_char;
 
 /// Return the number of newlines in a string.

src/wildcard.rs

@@ -13,7 +13,6 @@
 };
 use crate::complete::{CompleteFlags, Completion, CompletionReceiver, PROG_COMPLETE_SEP};
 use crate::expand::ExpandFlags;
-use crate::fallback::wcscasecmp;
 use crate::future_feature_flags::FeatureFlag;
 use crate::future_feature_flags::feature_test;
 use crate::wchar::prelude::*;
@@ -23,6 +22,7 @@
 };
 use crate::wutil::dir_iter::DirEntryType;
 use crate::wutil::{dir_iter::DirEntry, lwstat, waccess};
+use fish_fallback::wcscasecmp;
 
 localizable_consts!(
     COMPLETE_EXEC_DESC "command"

src/wutil/mod.rs

@@ -11,8 +11,8 @@
 use crate::common::{
     bytes2wcstring, fish_reserved_codepoint, wcs2bytes, wcs2osstring, wcs2zstring,
 };
+use crate::flog;
 use crate::wcstringutil::{join_strings, wcs2bytes_callback};
-use crate::{fallback, flog};
 use errno::errno;
 use fish_wchar::{L, WExt, WString, wstr};
 pub use gettext::{
@@ -448,7 +448,7 @@ pub fn fish_iswalnum(c: char) -> bool {
 }
 
 pub fn fish_wcswidth(s: &wstr) -> isize {
-    fallback::fish_wcswidth(s)
+    fish_fallback::fish_wcswidth(s)
 }
 
 /// Given that `cursor` is a pointer into `base`, return the offset in characters.