inject #line directives for better error reporting

1 files changed, 20 insertions, 3 deletions

diff --git a/src/main.zig b/src/main.zig
index 94ccab9..0181db6 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -157,6 +157,16 @@ pub fn main() !void {
     }
 }
 
+fn escape_dquote(str: []const u8) []const u8 {
+    const state = struct {
+        var buf: [1024]u8 = undefined;
+    };
+
+    const len = std.mem.replacementSize(u8, str, "\"", "\\\"");
+    _ = std.mem.replace(u8, str, "\"", "\\\"", state.buf[0..len]);
+    return state.buf[0..len];
+}
+
 // given a file and the directory it is in, resolve references
 fn loadFile(config: *const cfg.Config, writer: anytype, dir: []const u8, filename: []const u8) !void {
     const file_dir = try fs.path.resolve(c_allocator, &[_][]const u8{
@@ -172,11 +182,10 @@ fn loadFile(config: *const cfg.Config, writer: anytype, dir: []const u8, filenam
     defer file.close();
     var reader = file.reader();
 
-    var line_number: u32 = 0;
+    var line_number: u32 = 1;
     var buf: [1024]u8 = undefined;
+    var wrote_line = false;
     while (try reader.readUntilDelimiterOrEof(&buf, '\n')) |line| {
-        line_number += 1;
-
         if (std.mem.startsWith(u8, line, "#pragma ")) {
             var parts = std.mem.split(u8, line, " ");
             _ = parts.next();
@@ -192,6 +201,7 @@ fn loadFile(config: *const cfg.Config, writer: anytype, dir: []const u8, filenam
                 include_path = include_path[1 .. include_path.len - 1];
 
                 loadFile(config, writer, file_dir, include_path) catch unreachable;
+                _ = try writer.print("#line {d} \"{s}\"\n", .{ line_number, escape_dquote(filename) });
 
                 continue;
             } else {
@@ -200,8 +210,15 @@ fn loadFile(config: *const cfg.Config, writer: anytype, dir: []const u8, filenam
             }
         }
 
+        if (!std.mem.startsWith(u8, line, "#version") and !wrote_line) {
+            _ = try writer.print("#line {d} \"{s}\"\n", .{ line_number - 1, escape_dquote(filename) });
+            wrote_line = true;
+        }
+
         _ = try writer.write(line);
         _ = try writer.write("\n");
+
+        line_number += 1;
     }
 }