[DEV-7084] TAMER: CanonicalFile

This will be entirely replaced in an upcoming commit.  See that for
details.  I don't feel like dealing with the conflicts for rearranging and
squashing these commits.

tamer/src/fs.rs

@@ -42,7 +42,7 @@ use std::ffi::OsString;
 use std::fs;
 use std::hash::BuildHasher;
 use std::io::Result;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 /// A file.
 pub trait File
@@ -58,6 +58,23 @@ impl File for fs::File {
     }
 }
 
+pub struct CanonicalFile<F: File>(PathBuf, F);
+
+impl<F: File> Into<(PathBuf, F)> for CanonicalFile<F> {
+    fn into(self) -> (PathBuf, F) {
+        (self.0, self.1)
+    }
+}
+
+impl<F: File> File for CanonicalFile<F> {
+    fn open<P: AsRef<Path>>(path: P) -> Result<Self> {
+        let cpath = fs::canonicalize(path)?;
+        let file = F::open(&cpath)?;
+
+        Ok(Self(cpath, file))
+    }
+}
+
 /// A filesystem.
 ///
 /// Opening a file (using [`open`](Filesystem::open)) proxies to `F::open`.

tamer/src/ld/poc.rs

@@ -20,7 +20,9 @@
 //! **This is a poorly-written proof of concept; do not use!**  It has been
 //! banished to its own file to try to make that more clear.
 
-use crate::fs::{Filesystem, VisitOnceFile, VisitOnceFilesystem};
+use crate::fs::{
+    CanonicalFile, Filesystem, VisitOnceFile, VisitOnceFilesystem,
+};
 use crate::global;
 use crate::ir::asg::{
     Asg, AsgError, DefaultAsg, IdentKind, IdentObject, IdentObjectData,
@@ -34,6 +36,7 @@ use std::convert::TryInto;
 use std::error::Error;
 use std::fs;
 use std::io::BufReader;
+use std::path::PathBuf;
 
 type LinkerAsg<'i> = DefaultAsg<'i, IdentObject<'i>, global::ProgIdentSize>;
 type LinkerObjectRef = ObjectRef<global::ProgIdentSize>;
@@ -126,16 +129,17 @@ fn load_xmlo<'a, 'i, I: Interner<'i>>(
     interner: &'i I,
     roots: &mut Vec<LinkerObjectRef>,
 ) -> LoadResult<'i> {
-    let path = fs::canonicalize(path_str)?;
     let first = fs.visit_len() == 0;
 
     let mut found: FxHashSet<&str> = Default::default();
 
-    let file: fs::File = match fs.open(&path)? {
+    let cfile: CanonicalFile<fs::File> = match fs.open(path_str)? {
         VisitOnceFile::FirstVisit(file) => file,
         VisitOnceFile::Visited => return Ok(None),
     };
 
+    let (path, file) = cfile.into();
+
     let reader = BufReader::new(file);
     let mut xmlo: XmloReader<'_, _, _> = (reader, interner).into();
     let mut elig = None;
@@ -238,7 +242,7 @@ fn load_xmlo<'a, 'i, I: Interner<'i>>(
         ));
     }
 
-    let mut dir = path.clone();
+    let mut dir: PathBuf = path.clone();
     dir.pop();
 
     for relpath in found.iter() {