First draft of a diff-friendly profile

CHANGES.md

@@ -29,6 +29,7 @@
 - Format `.mld` files as odoc documentation files (#2008, @gpetiot)
 - New value `vertical` for option `if-then-else` (#2174, @gpetiot)
 - New value `vertical` for option `break-cases` (#2176, @gpetiot)
+- New profile: `diff-friendly`, aiming to minimize the vertical diff (#2020, @gpetiot)
 
 ## 0.24.1 (2022-07-18)
 

lib/Conf.ml

@@ -1565,6 +1565,69 @@ let conventional_profile =
 
 let default_profile = conventional_profile
 
+let diff_friendly_profile =
+  { align_pattern_matching_bar= `Keyword
+  ; assignment_operator= `End_line
+  ; break_before_in= `Fit_or_vertical
+  ; break_cases= `Vertical
+  ; break_collection_expressions= `Fit_or_vertical
+  ; break_colon= `After
+  ; break_infix= `Fit_or_vertical
+  ; break_infix_before_func= true
+  ; break_fun_decl= `Fit_or_vertical
+  ; break_fun_sig= `Fit_or_vertical
+  ; break_separators= `After
+  ; break_sequences= true
+  ; break_string_literals= `Auto
+  ; break_struct= true
+  ; cases_exp_indent= 4
+  ; cases_matching_exp_indent= `Compact
+  ; disambiguate_non_breaking_match= false
+  ; doc_comments= `Before_except_val
+  ; doc_comments_padding= 2
+  ; doc_comments_tag_only= `Default
+  ; dock_collection_brackets= true
+  ; exp_grouping= `Parens
+  ; extension_indent= 2
+  ; field_space= `Tight
+  ; function_indent= 2
+  ; function_indent_nested= `Never
+  ; if_then_else= `Vertical
+  ; indent_after_in= 0
+  ; indicate_multiline_delimiters= `Closing_on_separate_line
+  ; indicate_nested_or_patterns= `Unsafe_no
+  ; infix_precedence= `Indent
+  ; leading_nested_match_parens= false
+  ; let_and= `Sparse
+  ; let_binding_indent= 2
+  ; let_binding_spacing= `Compact
+  ; let_module= `Sparse
+  ; line_endings= `Lf
+  ; margin= 80
+  ; match_indent= 0
+  ; match_indent_nested= `Never
+  ; max_indent= None
+  ; module_item_spacing= `Sparse
+  ; nested_match= `Wrap
+  ; ocp_indent_compat= false
+  ; parens_ite= false
+  ; parens_tuple= `Always
+  ; parens_tuple_patterns= `Multi_line_only
+  ; parse_docstrings= false
+  ; parse_toplevel_phrases= false
+  ; sequence_blank_line= `Compact
+  ; sequence_style= `Separator
+  ; single_case= `Sparse
+  ; space_around_arrays= false
+  ; space_around_lists= false
+  ; space_around_records= false
+  ; space_around_variants= false
+  ; stritem_extension_indent= 0
+  ; type_decl= `Sparse
+  ; type_decl_indent= 2
+  ; wrap_comments= false
+  ; wrap_fun_args= false }
+
 let janestreet_profile =
   { align_pattern_matching_bar= `Keyword
   ; assignment_operator= `Begin_line
@@ -1643,6 +1706,8 @@ let profile =
          \"conventional\" appearing as the available options allow."
     ; C.Value.make ~name:"default" (Some default_profile)
         "$(b,default) is an alias for the $(b,conventional) profile."
+    ; C.Value.make ~name:"diff-friendly" (Some diff_friendly_profile)
+        "The $(b,diff_friendly) profile aims to minimize the vertical diff."
     ; C.Value.make ~name:"ocamlformat" (Some ocamlformat_profile)
         "The $(b,ocamlformat) profile aims to take advantage of the \
          strengths of a parsetree-based auto-formatter, and to limit the \

ocamlformat-help.txt

@@ -350,12 +350,13 @@ OPTIONS (CODE FORMATTING STYLE)
            Attempt to generate output which does not change (much) when
            post-processing with ocp-indent. The flag is unset by default.
 
-       -p {conventional|default|ocamlformat|janestreet},
-       --profile={conventional|default|ocamlformat|janestreet}
+       -p {conventional|default|diff-friendly|ocamlformat|janestreet},
+       --profile={conventional|default|diff-friendly|ocamlformat|janestreet}
            Select a preset profile which sets all options, overriding lower
            priority configuration. The conventional profile aims to be as
            familiar and "conventional" appearing as the available options
            allow. default is an alias for the conventional profile. The
+           diff_friendly profile aims to minimize the vertical diff. The
            ocamlformat profile aims to take advantage of the strengths of a
            parsetree-based auto-formatter, and to limit the consequences of
            the weaknesses imposed by the current implementation. This is a

test/passing/dune.inc

@@ -4750,6 +4750,24 @@
  (package ocamlformat)
  (action (diff tests/skip.ml.err skip.ml.stderr)))
 
+(rule
+ (deps tests/.ocamlformat )
+ (package ocamlformat)
+ (action
+  (with-stdout-to source-diff-friendly.ml.stdout
+   (with-stderr-to source-diff-friendly.ml.stderr
+     (run %{bin:ocamlformat} --margin-check --profile=diff-friendly --max-iters=3 %{dep:tests/source.ml})))))
+
+(rule
+ (alias runtest)
+ (package ocamlformat)
+ (action (diff tests/source-diff-friendly.ml.ref source-diff-friendly.ml.stdout)))
+
+(rule
+ (alias runtest)
+ (package ocamlformat)
+ (action (diff tests/source-diff-friendly.ml.err source-diff-friendly.ml.stderr)))
+
 (rule
  (deps tests/.ocamlformat )
  (package ocamlformat)

test/passing/tests/source-diff-friendly.ml.err

@@ -0,0 +1,3 @@
+Warning: tests/source.ml:5410 exceeds the margin
+Warning: tests/source.ml:7198 exceeds the margin
+Warning: tests/source.ml:8123 exceeds the margin

test/passing/tests/source-diff-friendly.ml.opts

@@ -0,0 +1,2 @@
+--profile=diff-friendly
+--max-iters=3