Build man pages into installable fish

This calls sphinx-build from build.rs to include the man pages in the binary.

We don't abort if sphinx doesn't exist, but we do if it failed.

build.rs

@@ -36,6 +36,12 @@ fn main() {
 
     std::env::set_var("FISH_BUILD_VERSION", version);
 
+    #[cfg(feature = "installable")]
+    {
+        let cman = std::fs::canonicalize(env!("CARGO_MANIFEST_DIR")).unwrap();
+        let targetman = cman.as_path().join("target").join("man");
+        build_man(&targetman);
+    }
     rsconf::rebuild_if_path_changed("src/libc.c");
     cc::Build::new()
         .file("src/libc.c")
@@ -307,3 +313,50 @@ fn get_version(src_dir: &Path) -> String {
 
     panic!("Could not get a version. Either set $FISH_BUILD_VERSION or install git.");
 }
+
+#[cfg(feature = "installable")]
+fn build_man(build_dir: &Path) {
+    use std::process::Command;
+    let mandir = build_dir;
+    let sec1dir = mandir.join("man1");
+    let docsrc_path = std::fs::canonicalize(env!("CARGO_MANIFEST_DIR"))
+        .unwrap()
+        .as_path()
+        .join("doc_src");
+    let docsrc = docsrc_path.to_str().unwrap();
+    let args = &[
+        "-j",
+        "auto",
+        "-q",
+        "-b",
+        "man",
+        "-c",
+        docsrc,
+        // doctree path - put this *above* the man1 dir to exclude it.
+        // this is ~6M
+        "-d",
+        mandir.to_str().unwrap(),
+        docsrc,
+        sec1dir.to_str().unwrap(),
+    ];
+    let _ = std::fs::create_dir_all(sec1dir.to_str().unwrap());
+
+    match Command::new("sphinx-build").args(args).output() {
+        Err(x) => {
+            println!("cargo:warning=Could not build man pages: {:?}", x);
+        }
+        Ok(x) => {
+            if !x.status.success() {
+                println!(
+                    "cargo:warning=Could not build man pages: {:?}",
+                    std::str::from_utf8(&x.stdout).unwrap()
+                );
+                println!(
+                    "cargo:warning=Could not build man pages: {:?}",
+                    std::str::from_utf8(&x.stderr).unwrap()
+                );
+                panic!("Building docs failed");
+            }
+        }
+    }
+}

src/bin/fish.rs

@@ -85,6 +85,11 @@ fn install(confirm: bool) {
     #[folder = "share/"]
     struct Asset;
 
+    #[derive(RustEmbed)]
+    #[folder = "target/man/man1"]
+    #[prefix = "man/man1/"]
+    struct Docs;
+
     use std::fs;
     use std::io::ErrorKind;
     use std::io::Write;
@@ -132,6 +137,8 @@ fn install(confirm: bool) {
         }
     }
 
+    // TODO: These are duplicated, no idea how to extract
+    //       them into a function
     for file in Asset::iter() {
         let path = dir.join(file.as_ref());
         let Ok(_) = fs::create_dir_all(path.parent().unwrap()) else {
@@ -153,6 +160,29 @@ fn install(confirm: bool) {
             std::process::exit(1);
         }
     }
+
+    for file in Docs::iter() {
+        let path = dir.join(file.as_ref());
+        let Ok(_) = fs::create_dir_all(path.parent().unwrap()) else {
+            eprintln!(
+                "Creating directory '{}' failed",
+                path.parent().unwrap().display()
+            );
+            std::process::exit(1);
+        };
+        let res = File::create(&path);
+        let Ok(mut f) = res else {
+            eprintln!("Creating file '{}' failed", path.display());
+            continue;
+        };
+        // This should be impossible.
+        let d = Docs::get(&file).expect("File was somehow not included???");
+        if let Err(error) = f.write_all(&d.data) {
+            eprintln!("error: {error}");
+            std::process::exit(1);
+        }
+    }
+
     let verfile = dir.join("fish-install-version");
     let res = File::create(&verfile);
     if let Ok(mut f) = res {