don't use full Pos for findPackageFilename/editorFor

only file and line of the returned position were ever used, it wasn't actually
used a position. as such we may as well use a path+int pair for only those two
values and remove a use of Pos that would not work well with a position table.

src/libcmd/command.cc

@@ -197,17 +197,17 @@ void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePath
     run(store, *storePaths.begin());
 }
 
-Strings editorFor(const Pos & pos)
+Strings editorFor(const Path & file, uint32_t line)
 {
     auto editor = getEnv("EDITOR").value_or("cat");
     auto args = tokenizeString<Strings>(editor);
-    if (pos.line > 0 && (
+    if (line > 0 && (
         editor.find("emacs") != std::string::npos ||
         editor.find("nano") != std::string::npos ||
         editor.find("vim") != std::string::npos ||
         editor.find("kak") != std::string::npos))
-        args.push_back(fmt("+%d", pos.line));
-    args.push_back(pos.file);
+        args.push_back(fmt("+%d", line));
+    args.push_back(file);
     return args;
 }
 

src/libcmd/command.hh

@@ -219,7 +219,7 @@ static RegisterCommand registerCommand2(std::vector<std::string> && name)
 
 /* Helper function to generate args that invoke $EDITOR on
    filename:lineno. */
-Strings editorFor(const Pos & pos);
+Strings editorFor(const Path & file, uint32_t line);
 
 struct MixProfile : virtual StoreCommand
 {

src/libexpr/attr-path.cc

@@ -106,7 +106,7 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const std::string &
 }
 
 
-Pos findPackageFilename(EvalState & state, Value & v, std::string what)
+std::pair<std::string, uint32_t> findPackageFilename(EvalState & state, Value & v, std::string what)
 {
     Value * v2;
     try {
@@ -132,9 +132,7 @@ Pos findPackageFilename(EvalState & state, Value & v, std::string what)
         throw ParseError("cannot parse line number '%s'", pos);
     }
 
-    Symbol file = state.symbols.create(filename);
-
-    return { foFile, file, lineno, 0 };
+    return { std::move(filename), lineno };
 }
 
 

src/libexpr/attr-path.hh

@@ -17,7 +17,7 @@ std::pair<Value *, Pos> findAlongAttrPath(
     Value & vIn);
 
 /* Heuristic to find the filename and lineno or a nix value. */
-Pos findPackageFilename(EvalState & state, Value & v, std::string what);
+std::pair<std::string, uint32_t> findPackageFilename(EvalState & state, Value & v, std::string what);
 
 std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s);
 

src/nix/edit.cc

@@ -30,17 +30,17 @@ struct CmdEdit : InstallableCommand
 
         auto [v, pos] = installable->toValue(*state);
 
-        try {
-            pos = findPackageFilename(*state, *v, installable->what());
-        } catch (NoPositionInfo &) {
-        }
-
-        if (pos == noPos)
-            throw Error("cannot find position information for '%s", installable->what());
+        const auto [file, line] = [&] {
+            try {
+                return findPackageFilename(*state, *v, installable->what());
+            } catch (NoPositionInfo &) {
+                throw Error("cannot find position information for '%s", installable->what());
+            }
+        }();
 
         stopProgressBar();
 
-        auto args = editorFor(pos);
+        auto args = editorFor(file, line);
 
         restoreProcessContext();
 

src/nix/repl.cc

@@ -461,21 +461,21 @@ bool NixRepl::processLine(std::string line)
         Value v;
         evalString(arg, v);
 
-        Pos pos;
-
-        if (v.type() == nPath || v.type() == nString) {
-            PathSet context;
-            auto filename = state->coerceToString(noPos, v, context);
-            pos.file = state->symbols.create(*filename);
-        } else if (v.isLambda()) {
-            pos = v.lambda.fun->pos;
-        } else {
-            // assume it's a derivation
-            pos = findPackageFilename(*state, v, arg);
-        }
+        const auto [file, line] = [&] () -> std::pair<std::string, uint32_t> {
+            if (v.type() == nPath || v.type() == nString) {
+                PathSet context;
+                auto filename = state->coerceToString(noPos, v, context);
+                return {state->symbols.create(*filename), 0};
+            } else if (v.isLambda()) {
+                return {v.lambda.fun->pos.file, v.lambda.fun->pos.line};
+            } else {
+                // assume it's a derivation
+                return findPackageFilename(*state, v, arg);
+            }
+        }();
 
         // Open in EDITOR
-        auto args = editorFor(pos);
+        auto args = editorFor(file, line);
         auto editor = args.front();
         args.pop_front();