Add tests for carriage return handling

Author: moosichu

test/compare_output.zig

@@ -528,4 +528,13 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         \\debug: free - len: 5
         \\
     );
+
+    cases.add("valid carriage return example", "const io = @import(\"std\").io;\r\n" ++ // Testing CRLF line endings are valid
+        "\r\n" ++
+        "pub \r fn main() void {\r\n" ++ // Testing isolated carriage return as whitespace is valid
+        "    const stdout = io.getStdOut().writer();\r\n" ++
+        "    stdout.print(\\A Multiline\r\n" ++ // testing CRLF at end of multiline string line is valid and normalises to \n in the output
+        "                 \\String\r\n" ++
+        "                 , .{}) catch unreachable;\r\n" ++
+        "}\r\n", "A Multiline\nString");
 }

test/compile_errors.zig

@@ -164,13 +164,23 @@ pub fn addCases(ctx: *TestContext) !void {
             \\    );
             \\}
         , &[_][]const u8{
-            \\:2:5: error: 
+            \\:2:5: error:
             \\             hello!
             \\             I'm a multiline error message.
             \\             I hope to be very useful!
-            \\             
+            \\
             \\             also I will leave this trailing newline here if you don't mind
-            \\             
+            \\
+        });
+    }
+
+    {
+        const case = ctx.obj("isolated carriage return in multiline string literal", .{});
+        case.backend = .stage2;
+
+        case.addError("const foo = \\\\\test\r\r rogue carriage return\n;", &[_][]const u8{
+            ":1:19: error: expected ';' after declaration",
+            ":1:20: note: invalid byte: '\\r'",
         });
     }