libexpr: use StorePath::to_string in string contexts

`path.abs()` does the same thing, but `to_string` communicates intent as well.

Change-Id: I9619a9f2e32317f0a1cc8e092ce8898471b980ac

lix/legacy/nix-env.cc

@@ -138,7 +138,7 @@ static void getAllExprs(Evaluator & state,
                 attrName = std::string(attrName, 0, attrName.size() - 4);
             if (!seen.insert(attrName).second) {
                 std::string suggestionMessage = "";
-                if (path2.path.abs().find("channels") != std::string::npos && path.path.abs().find("channels") != std::string::npos)
+                if (path2.to_string().find("channels") != std::string::npos && path.to_string().find("channels") != std::string::npos)
                     suggestionMessage = fmt("\nsuggestion: remove '%s' from either the root channels or the user channels", attrName);
                 printError("warning: name collision in input Nix expressions, skipping '%1%'"
                             "%2%", path2, suggestionMessage);

lix/libexpr/eval.cc

@@ -805,7 +805,7 @@ void EvalState::mkPos(Value & v, PosIdx p)
     auto origin = ctx.positions.originOf(p);
     if (auto path = std::get_if<SourcePath>(&origin)) {
         auto attrs = ctx.buildBindings(3);
-        attrs.alloc(ctx.s.file).mkString(path->path.abs());
+        attrs.alloc(ctx.s.file).mkString(path->to_string());
         makePositionThunks(*this, p, attrs.alloc(ctx.s.line), attrs.alloc(ctx.s.column));
         v.mkAttrs(attrs);
     } else
@@ -2269,7 +2269,7 @@ BackedStringView EvalState::coerceToString(
               v._path
             : copyToStore
             ? ctx.store->printStorePath(ctx.paths.copyPathToStore(context, v.path(), ctx.repair))
-            : std::string(v.path().path.abs());
+            : v.path().to_string();
     }
 
     if (v.type() == nAttrs) {

lix/libexpr/primops.cc

@@ -1153,7 +1153,7 @@ static void prim_toPath(EvalState & state, const PosIdx pos, Value * * args, Val
 {
     NixStringContext context;
     auto path = state.coerceToPath(pos, *args[0], context, "while evaluating the first argument passed to builtins.toPath");
-    v.mkString(path.path.abs(), context);
+    v.mkString(path.to_string(), context);
 }
 
 /* Allow a valid store path to be used in an expression.  This is

lix/libexpr/value-to-json.cc

@@ -39,7 +39,7 @@ json printValueAsJSON(EvalState & state, bool strict,
                 out = state.ctx.store->printStorePath(
                     state.ctx.paths.copyPathToStore(context, v.path(), state.ctx.repair));
             else
-                out = v.path().path.abs();
+                out = v.path().to_string();
             break;
 
         case nNull:

lix/libexpr/value-to-xml.cc

@@ -22,7 +22,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
 static void posToXML(EvalState & state, XMLAttrs & xmlAttrs, const Pos & pos)
 {
     if (auto path = std::get_if<SourcePath>(&pos.origin))
-        xmlAttrs["path"] = path->path.abs();
+        xmlAttrs["path"] = path->to_string();
     xmlAttrs["line"] = fmt("%1%", pos.line);
     xmlAttrs["column"] = fmt("%1%", pos.column);
 }