Remove range format markers when using --lines and --diff together

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [v1.4.5] - 2025-07-24
+### Fixed
+ - Fix `--diff` output in combination with `--lines`. Previously the internal makers used to
+   mark the lines to be formatted would show up in the diff output. ([#154]).
+
 ## [v1.4.4] - 2025-07-24
 ### Fixed
  - Fix another edgecase where adding a trailing comma after the last item in a list results

Project.toml

@@ -1,6 +1,6 @@
 name = "Runic"
 uuid = "62bfec6d-59d7-401d-8490-b29ee721c001"
-version = "1.4.4"
+version = "1.4.5"
 
 [deps]
 JuliaSyntax = "70703baa-626e-46a2-a12c-08ffd08c73b4"

src/main.jl

@@ -468,15 +468,32 @@ function main(argv)
                 file = basename(inputfile)
                 A = joinpath(a, file)
                 B = joinpath(b, file)
+                src_str = ctx.src_str
+                # If we have ranges we need to remove the comment markers
+                # TODO: It isn't great that the source string has been modified to begin
+                #       with, and to support --lines in the API functions this filtering
+                #       needs to be moved to the `format_tree` function.
+                if !isempty(line_ranges)
+                    io = IOBuffer(; sizehint = sizeof(src_str))
+                    for line in eachline(IOBuffer(src_str); keep = true)
+                        if !(
+                                occursin(RANGE_FORMATTING_BEGIN, line) ||
+                                    occursin(RANGE_FORMATTING_END, line)
+                            )
+                            write(io, line)
+                        end
+                    end
+                    src_str = String(take!(io))
+                end
                 # juliac: `open(...) do` uses dynamic dispatch otherwise the following
                 # blocks could be written as
                 # ```
-                # write(A, ctx.src_str)
+                # write(A, src_str)
                 # write(B, seekstart(ctx.fmt_io))
                 # ```
                 let io = open(A, "w")
                     try
-                        write(io, ctx.src_str)
+                        write(io, src_str)
                     finally
                         close(io)
                     end

test/maintests.jl

@@ -543,6 +543,16 @@ function maintests(f::R) where {R}
         rc, fd1, fd2 = runic(["--lines=3:4", "."])
         @test rc == 1 && isempty(fd1)
         @test occursin("option `--lines` can not be used together with multiple input files", fd2)
+        # --diff and --lines: no comment markers in diff output
+        if Sys.which("git") !== nothing
+            rc, fd1, fd2 = runic(["--lines=1:1", "--diff"], src)
+            @test rc == 0
+            @test fd1 == "function f(a, b)\n    return a+b\n end\n"
+            @test occursin("-function f(a,b)", fd2)
+            @test occursin("+function f(a, b)", fd2)
+            @test !occursin(Runic.RANGE_FORMATTING_BEGIN, fd2)
+            @test !occursin(Runic.RANGE_FORMATTING_END, fd2)
+        end
     end
 
     return