config: show filepath and line numbers for config errors

Fixes #1063

src/cli/args.zig

@@ -961,7 +961,7 @@ pub fn LineIterator(comptime ReaderType: type) type {
 }
 
 // Constructs a LineIterator (see docs for that).
-pub fn lineIterator(reader: anytype) LineIterator(@TypeOf(reader)) {
+fn lineIterator(reader: anytype) LineIterator(@TypeOf(reader)) {
     return .{ .r = reader };
 }
 

src/config/Config.zig

@@ -2260,7 +2260,9 @@ pub fn loadFile(self: *Config, alloc: Allocator, path: []const u8) !void {
     std.log.info("reading configuration file path={s}", .{path});
 
     var buf_reader = std.io.bufferedReader(file.reader());
-    var iter = cli.args.lineIterator(buf_reader.reader());
+    const reader = buf_reader.reader();
+    const Iter = cli.args.LineIterator(@TypeOf(reader));
+    var iter: Iter = .{ .r = reader, .filepath = path };
     try self.loadIter(alloc, &iter);
     try self.expandPaths(std.fs.path.dirname(path).?);
 }
@@ -2471,7 +2473,9 @@ pub fn loadRecursiveFiles(self: *Config, alloc_gpa: Allocator) !void {
 
         log.info("loading config-file path={s}", .{path});
         var buf_reader = std.io.bufferedReader(file.reader());
-        var iter = cli.args.lineIterator(buf_reader.reader());
+        const reader = buf_reader.reader();
+        const Iter = cli.args.LineIterator(@TypeOf(reader));
+        var iter: Iter = .{ .r = reader, .filepath = path };
         try self.loadIter(alloc_gpa, &iter);
         try self.expandPaths(std.fs.path.dirname(path).?);
     }
@@ -2502,11 +2506,13 @@ fn expandPaths(self: *Config, base: []const u8) !void {
 
 fn loadTheme(self: *Config, theme: []const u8) !void {
     // Find our theme file and open it. See the open function for details.
-    const file: std.fs.File = (try themepkg.open(
+    const themefile = (try themepkg.open(
         self._arena.?.allocator(),
         theme,
         &self._diagnostics,
     )) orelse return;
+    const path = themefile.path;
+    const file = themefile.file;
     defer file.close();
 
     // From this point onwards, we load the theme and do a bit of a dance
@@ -2532,7 +2538,9 @@ fn loadTheme(self: *Config, theme: []const u8) !void {
 
     // Load our theme
     var buf_reader = std.io.bufferedReader(file.reader());
-    var iter = cli.args.lineIterator(buf_reader.reader());
+    const reader = buf_reader.reader();
+    const Iter = cli.args.LineIterator(@TypeOf(reader));
+    var iter: Iter = .{ .r = reader, .filepath = path };
     try new_config.loadIter(alloc_gpa, &iter);
 
     // Replay our previous inputs so that we can override values

src/config/theme.zig

@@ -108,14 +108,20 @@ pub fn open(
     arena_alloc: Allocator,
     theme: []const u8,
     diags: *cli.DiagnosticList,
-) error{OutOfMemory}!?std.fs.File {
+) error{OutOfMemory}!?struct {
+    path: []const u8,
+    file: std.fs.File,
+} {
 
     // Absolute themes are loaded a different path.
-    if (std.fs.path.isAbsolute(theme)) return try openAbsolute(
-        arena_alloc,
-        theme,
-        diags,
-    );
+    if (std.fs.path.isAbsolute(theme)) {
+        const file: std.fs.File = try openAbsolute(
+            arena_alloc,
+            theme,
+            diags,
+        ) orelse return null;
+        return .{ .path = theme, .file = file };
+    }
 
     const basename = std.fs.path.basename(theme);
     if (!std.mem.eql(u8, theme, basename)) {
@@ -135,8 +141,9 @@ pub fn open(
     const cwd = std.fs.cwd();
     while (try it.next()) |loc| {
         const path = try std.fs.path.join(arena_alloc, &.{ loc.dir, theme });
-        if (cwd.openFile(path, .{})) |file| {
-            return file;
+        if (cwd.openFile(path, .{})) |file| return .{
+            .path = path,
+            .file = file,
         } else |err| switch (err) {
             // Not an error, just continue to the next location.
             error.FileNotFound => {},