libutil: remove SourcePath::getPhysicalPath

all files are physical, so this doesn't have to be optional. if it only
returns a copy of a member it's not useful either, but performance cost

Change-Id: Ib2f935ae247d96418d55bc100e04765dc586528b

lix/legacy/nix-instantiate.cc

@@ -168,10 +168,7 @@ static int main_nix_instantiate(std::string programName, Strings argv)
         if (findFile) {
             for (auto & i : files) {
                 auto p = evaluator->paths.findFile(i);
-                if (auto fn = p.getPhysicalPath())
-                    std::cout << fn->abs() << std::endl;
-                else
-                    throw Error("'%s' has no physical path", p);
+                std::cout << p.path.abs() << std::endl;
             }
             return 0;
         }

lix/libcmd/editor-for.cc

@@ -7,9 +7,6 @@ namespace nix {
 
 Strings editorFor(const SourcePath & file, uint32_t line)
 {
-    auto path = file.getPhysicalPath();
-    if (!path)
-        throw Error("cannot open '%s' in an editor because it has no physical path", file);
     auto editor = getEnv("EDITOR").value_or("cat");
     auto args = tokenizeString<Strings>(editor);
     if (line > 0 && (
@@ -18,7 +15,7 @@ Strings editorFor(const SourcePath & file, uint32_t line)
         editor.find("vim") != std::string::npos ||
         editor.find("kak") != std::string::npos))
         args.push_back(fmt("+%d", line));
-    args.push_back(path->abs());
+    args.push_back(file.path.abs());
     return args;
 }
 

lix/libutil/source-path.hh

@@ -103,13 +103,6 @@ struct SourcePath
         PathFilter & filter = defaultPathFilter) const
     { sink << nix::dumpPath(path.abs(), filter); }
 
-    /**
-     * Return the location of this path in the "real" filesystem, if
-     * it has a physical location.
-     */
-    std::optional<CanonPath> getPhysicalPath() const
-    { return path; }
-
     std::string to_string() const
     { return path.abs(); }