Extract constant for resolved build directory

Also use a different name than for the CMake variable, to reduce
confusion.

(cherry picked from commit a0b22077a5)

build.rs

@@ -16,7 +16,7 @@ fn main() {
     // language server.
 
     rsconf::set_env_value(
-        "FISH_BUILD_DIR",
+        "FISH_RESOLVED_BUILD_DIR",
         // If set by CMake, this might include symlinks. Since we want to compare this to the
         // dir fish is executed in we need to canonicalize it.
         canonicalize(fish_build_dir()).to_str().unwrap(),

crates/build-helper/src/lib.rs

@@ -12,7 +12,7 @@ fn cargo_target_dir() -> Cow<'static, Path> {
 }
 
 pub fn fish_build_dir() -> Cow<'static, Path> {
-    // FISH_BUILD_DIR is set by CMake, if we are using it.
+    // This is set if using CMake.
     option_env!("FISH_BUILD_DIR")
         .map(|d| Cow::Borrowed(Path::new(d)))
         .unwrap_or(cargo_target_dir())

src/common.rs

@@ -32,6 +32,8 @@
 use std::sync::{Arc, MutexGuard};
 use std::time;
 
+pub const BUILD_DIR: &str = env!("FISH_RESOLVED_BUILD_DIR");
+
 pub const PACKAGE_NAME: &str = env!("CARGO_PKG_NAME");
 
 // Highest legal ASCII value.

src/env/config_paths.rs

@@ -72,6 +72,8 @@ fn from_exec_path(exec_path: PathBuf) -> Self {
     fn from_exec_path(unresolved_exec_path: PathBuf) -> Self {
         use std::path::Path;
 
+        use crate::common::BUILD_DIR;
+
         let invalid_exec_path = |exec_path: &Path| {
             FLOG!(
                 config,
@@ -116,7 +118,7 @@ fn from_exec_path(unresolved_exec_path: PathBuf) -> Self {
         }
 
         // If we're in Cargo's target directory or in CMake's build directory, use the source files.
-        if exec_path.starts_with(env!("FISH_BUILD_DIR")) {
+        if exec_path.starts_with(BUILD_DIR) {
             FLOG!(
                 config,
                 format!(

src/path.rs

@@ -585,10 +585,10 @@ fn make_base_directory(xdg_var: &wstr, non_xdg_homepath: &wstr) -> BaseDirectory
     // the actual $HOME or $XDG_XXX directories. This prevents the tests from failing and/or stops
     // the tests polluting the user's actual $HOME if a sandbox environment has not been set up.
     {
-        use crate::common::str2wcstring;
+        use crate::common::{str2wcstring, BUILD_DIR};
         use std::path::PathBuf;
 
-        let mut build_dir = PathBuf::from(env!("FISH_BUILD_DIR"));
+        let mut build_dir = PathBuf::from(BUILD_DIR);
         build_dir.push("fish-test-home");
 
         let err = match std::fs::create_dir_all(&build_dir) {

src/tests/mod.rs

@@ -29,7 +29,7 @@
 mod wgetopt;
 
 pub mod prelude {
-    use crate::common::{ScopeGuard, ScopeGuarding};
+    use crate::common::{ScopeGuard, ScopeGuarding, BUILD_DIR};
     use crate::env::{env_init, misc_init};
     use crate::parser::{CancelBehavior, Parser};
     use crate::reader::{reader_deinit, reader_init};
@@ -88,9 +88,9 @@ fn deref(&self) -> &Self::Target {
     pub fn test_init() -> impl ScopeGuarding<Target = ()> {
         static DONE: OnceCell<()> = OnceCell::new();
         DONE.get_or_init(|| {
-            // If we are building with `cargo build` and have build w/ `cmake`, FISH_BUILD_DIR might
-            // not yet exist.
-            let mut test_dir = PathBuf::from(env!("FISH_BUILD_DIR"));
+            // If we are building with `cargo build` and have build w/ `cmake`, this might not
+            // yet exist.
+            let mut test_dir = PathBuf::from(BUILD_DIR);
             test_dir.push("fish-test");
             std::fs::create_dir_all(&test_dir).unwrap();
             set_current_dir(&test_dir).unwrap();