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[Formatter] Add trailing comma after last element in multiline call argument list #17018

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[Formatter] Add trailing comma after last element in multiline call argument list #17018

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7517cb1
Write trailing comma in a multiline call argument list
Sija May 28, 2026
27cf9bc
Adjust the specs
Sija May 27, 2026
a601ac4
Add more specs
Sija May 27, 2026
032b3ca
Run `crystal tool format`
Sija May 28, 2026
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2 changes: 1 addition & 1 deletion samples/sdl/raytracer.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -214,7 +214,7 @@ scene = Scene.new(
],
[
Light.new(Vec3.new(-10.0, 20.0, 30.0), Vec3.new(2.0, 2.0, 2.0)),
]
],
)

SDL.init
Expand Down
2 changes: 1 addition & 1 deletion samples/text_raytracer.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,7 @@ scene = [

ray = Ray.new(
Vector.new(0.0, 0.0, 0.0),
Vector.new((fi - fw/2.0)/fw, (fj - fh/2.0)/fh, 1.0).normalize
Vector.new((fi - fw/2.0)/fw, (fj - fh/2.0)/fh, 1.0).normalize,
)

hit = nil
Expand Down
2 changes: 1 addition & 1 deletion scripts/github-changelog.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,7 @@ def query_prs(api_token, repository, milestone : String, cursor : String?)
body: {query: query, variables: variables}.to_json,
headers: HTTP::Headers{
"Authorization" => "bearer #{api_token}",
}
},
)
unless response.success?
abort "GitHub API response: #{response.status}\n#{response.body}"
Expand Down
2 changes: 1 addition & 1 deletion spec/compiler/crystal/tools/init_spec.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ end

private def run_init_project(skeleton_type, name, author, email, github_name, dir = name)
Crystal::Init::InitProject.new(
Crystal::Init::Config.new(skeleton_type, name, dir, author, email, github_name, true)
Crystal::Init::Config.new(skeleton_type, name, dir, author, email, github_name, true),
).run
end

Expand Down
2 changes: 1 addition & 1 deletion spec/compiler/ffi/ffi_spec.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,7 @@ describe Crystal::FFI::CallInterface do
j: 8,
f: 9.0,
d: 10.0,
p: pointerof(pointer_value).as(Void*)
p: pointerof(pointer_value).as(Void*),
)).as(Void*),
Pointer(Void).null,
]
Expand Down
59 changes: 36 additions & 23 deletions spec/compiler/formatter/formatter_spec.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,7 @@ describe Crystal::Formatter do
assert_format "[\n1,\n\n2]", "[\n 1,\n\n 2,\n]"
assert_format "[ # foo\n 1,\n]"
assert_format "Set{ # foo\n 1,\n}"
assert_format "begin\n array[\n 0 # Zero\n ]\nend"
assert_format "begin\n array[\n 0 # Zero\n ]\nend", "begin\n array[\n 0, # Zero\n ]\nend"
assert_format "begin\n array[\n 0, # Zero\n ]\nend"
assert_format "[\n # foo\n] of String"
assert_format "[\n# foo\n] of String", "[\n # foo\n] of String"
Expand Down Expand Up @@ -459,7 +459,7 @@ describe Crystal::Formatter do
CRYSTAL
module M
@[MyAnn(
1
1,
)]
end
CRYSTAL
Expand Down Expand Up @@ -508,8 +508,8 @@ describe Crystal::Formatter do
assert_format "::foo(1, 2)"
assert_format "args.any? &.name.baz"
assert_format "foo(\n 1, 2)", "foo(\n 1, 2)"
assert_format "foo(\n1,\n 2 \n)", "foo(\n 1,\n 2\n)"
assert_format "foo(\n1,\n\n 2 \n)", "foo(\n 1,\n\n 2\n)"
assert_format "foo(\n1,\n 2 \n)", "foo(\n 1,\n 2,\n)"
assert_format "foo(\n1,\n\n 2 \n)", "foo(\n 1,\n\n 2,\n)"
assert_format "foo(\n 1,\n # 2,\n 3,\n)"
assert_format "foo(\n 1,\n # 2,\n # 3,\n)"
assert_format "foo 1,\n2", "foo 1,\n 2"
Expand All @@ -518,7 +518,7 @@ describe Crystal::Formatter do
assert_format "foo bar:baz, qux:other", "foo bar: baz, qux: other"
assert_format "foo(\n 1, 2, &block)", "foo(\n 1, 2, &block)"
assert_format "foo(\n 1, 2,\n&block)", "foo(\n 1, 2,\n &block)"
assert_format "foo(\n 1,\n 2\n) do\n 1\nend"
assert_format "foo(\n 1,\n 2\n) do\n 1\nend", "foo(\n 1,\n 2,\n) do\n 1\nend"
assert_format "foo 1, a: 1,\nb: 2,\nc: 3,\n&block", "foo 1, a: 1,\n b: 2,\n c: 3,\n &block"
assert_format "foo 1, do\n2\nend", "foo 1 do\n 2\nend"
assert_format "a.b &.[c]?\n1"
Expand All @@ -536,7 +536,7 @@ describe Crystal::Formatter do
assert_format "foo.% bar"
assert_format "foo.bar(&.%(baz))"
assert_format "foo.bar(&.% baz)"
assert_format "if 1\n foo(\n bar\n # comment\n )\nend"
assert_format "if 1\n foo(\n bar\n # comment\n )\nend", "if 1\n foo(\n bar,\n # comment\n )\nend"
assert_format "if 1\n foo(\n bar,\n # comment\n )\nend"

assert_format "foo.bar\n.baz", "foo.bar\n .baz"
Expand Down Expand Up @@ -1848,7 +1848,7 @@ describe Crystal::Formatter do
assert_format "[\n a(), # b\n]", "[\n a(), # b\n]"
assert_format "[\n a(),\n]", "[\n a(),\n]"
assert_format "if 1\n[\n a() # b\n]\nend", "if 1\n [\n a(), # b\n ]\nend"
assert_format "foo(\n# x\n1,\n\n# y\nz: 2\n)", "foo(\n # x\n 1,\n\n # y\n z: 2\n)"
assert_format "foo(\n# x\n1,\n\n# y\nz: 2\n)", "foo(\n # x\n 1,\n\n # y\n z: 2,\n)"
assert_format "foo(\n# x\n1,\n\n# y\nz: 2,\n\n# a\nb: 3)", "foo(\n # x\n 1,\n\n # y\n z: 2,\n\n # a\n b: 3)"
assert_format "foo(\n 1, # hola\n2, # chau\n )", "foo(\n 1, # hola\n 2, # chau\n)"
assert_format "foo (1)", "foo(1)"
Expand Down Expand Up @@ -1886,7 +1886,7 @@ describe Crystal::Formatter do
assert_format "case 1\nwhen 2\n 3\n # foo\nelse\n 4\n # bar\nend"
assert_format "1 #=> 2", "1 # => 2"
assert_format "1 #=>2", "1 # => 2"
assert_format "foo(\n [\n 1,\n 2,\n ],\n [\n 3,\n 4,\n ]\n)"
assert_format "foo(\n [\n 1,\n 2,\n ],\n [\n 3,\n 4,\n ]\n)", "foo(\n [\n 1,\n 2,\n ],\n [\n 3,\n 4,\n ],\n)"
assert_format "begin\n %w(\n one two\n three four\n )\nend"
assert_format "%w(\n one two\n three four\n)"
assert_format "a = %w(\n one two\n three four\n)"
Expand All @@ -1904,8 +1904,8 @@ describe Crystal::Formatter do
assert_format "foo(1, 2, {\n foo: 1,\n bar: 2,\n})"
assert_format "a = foo(1, 2, {\n foo: 1,\n bar: 2,\n})"
assert_format "foo([\n 1,\n bar do\n end,\n [\n 2,\n ],\n])"
assert_format "foo(bar(\n 1,\n baz(\n 2,\n 3,\n )\n))"
assert_format "foo(bar(\n 1,\n baz(2,\n 3,\n )\n))", "foo(bar(\n 1,\n baz(2,\n 3,\n )\n))"
assert_format "foo(bar(\n 1,\n baz(\n 2,\n 3,\n )\n))", "foo(bar(\n 1,\n baz(\n 2,\n 3,\n ),\n))"
assert_format "foo(bar(\n 1,\n baz(2,\n 3,\n )\n))", "foo(bar(\n 1,\n baz(2,\n 3,\n ),\n))"
assert_format "foo({\n 1 => 2,\n 3 => {\n 4 => 5,\n },\n})"
assert_format "foo([\n 1, 2,\n 3, 4,\n])"
assert_format "foo(baz(x, y) do\n 1 + 2\nend)"
Expand Down Expand Up @@ -1962,7 +1962,7 @@ describe Crystal::Formatter do
assert_format "begin\nend\n\n# a\n", "begin\n\nend\n\n# a"
assert_format "begin\n 1\nend\n\n1\n", "begin\n 1\nend\n\n1"
assert_format "{\n \"a\" => 1, \"b\" => 2,\n \"foo\" => 3, \"bar\" => 4,\n \"coconio\" => 5, \"lala\" => 6,\n}\n", "{\n \"a\" => 1, \"b\" => 2,\n \"foo\" => 3, \"bar\" => 4,\n \"coconio\" => 5, \"lala\" => 6,\n}"
assert_format "if 1\n foo(\n 1,\n 2 # lala\n )\nend\n", "if 1\n foo(\n 1,\n 2 # lala\n )\nend"
assert_format "if 1\n foo(\n 1,\n 2 # lala\n )\nend\n", "if 1\n foo(\n 1,\n 2, # lala\n )\nend"
assert_format "case foo\nwhen 1\n # A\nelse\n# B\nend\n", "case foo\nwhen 1\n # A\nelse\n # B\nend"
assert_format "return 1\n# end"
assert_format "case\n# hello\nwhen 1\n 2\nend"
Expand Down Expand Up @@ -2282,8 +2282,8 @@ describe Crystal::Formatter do
assert_format "def a\n {\n 1, # x\n # y\n }\nend"
assert_format "def a\n [\n 1, # x\n # y\n ]\nend"
assert_format "def a\n b(\n 1, # x\n # y\n )\nend"
assert_format "def a\n b(\n 1, # x\n # y\n 2\n )\nend"
assert_format "def a\n b(\n a: 1, # x\n # y\n b: 2\n )\nend"
assert_format "def a\n b(\n 1, # x\n # y\n 2\n )\nend", "def a\n b(\n 1, # x\n # y\n 2,\n )\nend"
assert_format "def a\n b(\n a: 1, # x\n # y\n b: 2\n )\nend", "def a\n b(\n a: 1, # x\n # y\n b: 2,\n )\nend"
assert_format "def a\n b(\n 1, # x\n # y\n a: 1, # x\n # y\n b: 2 # z\n )\nend"

assert_format "def foo(a, **b : Int32)\nend"
Expand Down Expand Up @@ -2390,36 +2390,36 @@ describe Crystal::Formatter do
" <<-FOO\n" +
" hello \n" +
" FOO\n" +
"end"
"end",
)
assert_format(
"{% verbatim do %}\n" +
" <<-FOO\n" +
" hello \n" +
" FOO\n" +
"{% end %}"
"{% end %}",
)
assert_format(
"{% if true %}\n" +
" <<-FOO\n" +
" hello \n" +
" FOO\n" +
"{% end %}"
"{% end %}",
)
assert_format(
"{% for a in %w() %}\n" +
" <<-FOO\n" +
" hello \n" +
" FOO\n" +
"{% end %}"
"{% end %}",
)
assert_format(
"macro foo\n" +
" {{x}}" +
" <<-FOO\n" +
" hello \n" +
" FOO\n" +
"end"
"end",
)

# But remove trailing space in macro expression.
Expand All @@ -2437,7 +2437,7 @@ describe Crystal::Formatter do
" 42\n" +
" }} \n" +
" 2 \n" +
"end"
"end",
)

# #7443
Expand Down Expand Up @@ -2468,13 +2468,26 @@ describe Crystal::Formatter do
# #7614
assert_format "@[ Foo ]\ndef foo\nend", "@[Foo]\ndef foo\nend"
assert_format "@[ Foo(foo: 1) ]\ndef foo\nend", "@[Foo(foo: 1)]\ndef foo\nend"
assert_format "@[Foo(\n foo: 1\n)]\ndef foo\nend"
assert_format "@[Foo(\n foo: 1\n)]\ndef foo\nend", "@[Foo(\n foo: 1,\n)]\ndef foo\nend"
assert_format "@[Foo(\n foo: 1,\n)]\ndef foo\nend"

# #7550
assert_format "foo\n .bar(\n 1\n )"
assert_format "foo\n .bar\n .baz(\n 1\n )"
assert_format "foo.bar\n .baz(\n 1\n )"
assert_format "foo\n .bar(\n 1\n )", "foo\n .bar(\n 1,\n )"
assert_format "foo\n .bar\n .baz(\n 1\n )", "foo\n .bar\n .baz(\n 1,\n )"
assert_format "foo.bar\n .baz(\n 1\n )", "foo.bar\n .baz(\n 1,\n )"

# #17018
assert_format "foo(\n 1,\n bar: 2\n)", "foo(\n 1,\n bar: 2,\n)"
assert_format "foo(\n bar: 1\n)", "foo(\n bar: 1,\n)"
assert_format "foo(\n bar: 1 # fox\n)", "foo(\n bar: 1, # fox\n)"
assert_format "foo(\n 1 # fox\n)", "foo(\n 1, # fox\n)"
assert_format "foo(\n 1\n)", "foo(\n 1,\n)"
assert_format "foo(\n 1,\n &block\n)"
assert_format "foo \\\n 1,\n bar: 2"
assert_format "foo \\\n 1"
assert_format "foo(\n 1,\n bar: <<-HEREDOC\n foo\n HEREDOC\n)"

@straight-shoota straight-shoota May 28, 2026

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question: Shouldn't we add a comma here?

Suggested change
assert_format "foo(\n 1,\n bar: <<-HEREDOC\n foo\n HEREDOC\n)"
assert_format "foo(\n 1,\n bar: <<-HEREDOC\n foo\n HEREDOC\n)", "foo(\n 1,\n bar: <<-HEREDOC,\n foo\n HEREDOC\n)"

Btw. we might want to use heredocs for the strings to makes the examples easier to read.

assert_format "foo(\n bar: <<-HEREDOC\n foo\n HEREDOC\n)"
assert_format "foo(\n <<-HEREDOC\n foo\n HEREDOC\n)"

assert_format <<-CRYSTAL,
def foo
Expand Down
38 changes: 19 additions & 19 deletions spec/compiler/macro/macro_methods_spec.cr
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -851,7 +851,7 @@ module Crystal
it "#each" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% [1, 2, 3].each { |v| values << v } %}{{values}}{% end %}),
%([1, 2, 3])
%([1, 2, 3]),
)
end

Expand All @@ -860,7 +860,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% [1, 2, 3].each_with_index { |v, idx| values << (v + idx) } %}{{values}}{% end %}),
%([1, 3, 5])
%([1, 3, 5]),
)
end
end
Expand All @@ -869,7 +869,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% [1, 2, 3].each_with_index { |v| values << v } %}{{values}}{% end %}),
%([1, 2, 3])
%([1, 2, 3]),
)
end
end
Expand All @@ -878,7 +878,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% [1, 2, 3].each_with_index { |_, idx| values << idx } %}{{values}}{% end %}),
%([0, 1, 2])
%([0, 1, 2]),
)
end
end
Expand All @@ -887,7 +887,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% [1, 2, 3].each_with_index { values << 7 } %}{{values}}{% end %}),
%([7, 7, 7])
%([7, 7, 7]),
)
end
end
Expand Down Expand Up @@ -1174,7 +1174,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {"k1" => "v1", "k2" => "v2"}.each { |k, v| values << {k, v} } %}{{values}}{% end %}),
%([{"k1", "v1"}, {"k2", "v2"}])
%([{"k1", "v1"}, {"k2", "v2"}]),
)
end
end
Expand All @@ -1183,7 +1183,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {"k1" => "v1", "k2" => "v2"}.each { |k| values << k } %}{{values}}{% end %}),
%(["k1", "k2"])
%(["k1", "k2"]),
)
end
end
Expand All @@ -1192,7 +1192,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {"k1" => "v1", "k2" => "v2"}.each { |_, v| values << v } %}{{values}}{% end %}),
%(["v1", "v2"])
%(["v1", "v2"]),
)
end
end
Expand All @@ -1201,7 +1201,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {"k1" => "v1", "k2" => "v2"}.each { values << {"k3", "v3"} } %}{{values}}{% end %}),
%([{"k3", "v3"}, {"k3", "v3"}])
%([{"k3", "v3"}, {"k3", "v3"}]),
)
end
end
Expand Down Expand Up @@ -1303,7 +1303,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {k1: "v1", k2: "v2"}.each { |k, v| values << {k, v} } %}{{values}}{% end %}),
%([{k1, "v1"}, {k2, "v2"}])
%([{k1, "v1"}, {k2, "v2"}]),
)
end
end
Expand All @@ -1312,7 +1312,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {k1: "v1", k2: "v2"}.each { |k| values << k } %}{{values}}{% end %}),
%([k1, k2])
%([k1, k2]),
)
end
end
Expand All @@ -1321,7 +1321,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {k1: "v1", k2: "v2"}.each { |_, v| values << v } %}{{values}}{% end %}),
%(["v1", "v2"])
%(["v1", "v2"]),
)
end
end
Expand All @@ -1330,7 +1330,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {k1: "v1", k2: "v2"}.each { values << {"k3", "v3"} } %}{{values}}{% end %}),
%([{"k3", "v3"}, {"k3", "v3"}])
%([{"k3", "v3"}, {"k3", "v3"}]),
)
end
end
Expand Down Expand Up @@ -1454,7 +1454,7 @@ module Crystal
it "#each" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {1, 2, 3}.each { |v| values << v } %}{{values}}{% end %}),
%([1, 2, 3])
%([1, 2, 3]),
)
end

Expand All @@ -1463,7 +1463,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {1, 2, 3}.each_with_index { |v, idx| values << (v + idx) } %}{{values}}{% end %}),
%([1, 3, 5])
%([1, 3, 5]),
)
end
end
Expand All @@ -1472,7 +1472,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {1, 2, 3}.each_with_index { |v| values << v } %}{{values}}{% end %}),
%([1, 2, 3])
%([1, 2, 3]),
)
end
end
Expand All @@ -1481,7 +1481,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {1, 2, 3}.each_with_index { |_, idx| values << idx } %}{{values}}{% end %}),
%([0, 1, 2])
%([0, 1, 2]),
)
end
end
Expand All @@ -1490,7 +1490,7 @@ module Crystal
it "builds the correct array" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% {1, 2, 3}.each_with_index { values << 7 } %}{{values}}{% end %}),
%([7, 7, 7])
%([7, 7, 7]),
)
end
end
Expand Down Expand Up @@ -3480,7 +3480,7 @@ module Crystal
it "#each" do
assert_macro(
%({% begin %}{% values = [] of Nil %}{% (1..3).each { |v| values << v } %}{{values}}{% end %}),
%([1, 2, 3])
%([1, 2, 3]),
)
end
end
Expand Down
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