Simplify Set#inspect output

As Set is now a core collection class, it should have special inspect
output.  Ideally, inspect output should be suitable to eval, similar
to array and hash (assuming the elements are also suitable to eval):

  set = Set[1, 2, 3]
  eval(set.inspect) == set # should be true

The simplest way to do this is to use the Set[] syntax.

This deliberately does not use any subclass name in the output,
similar to array and hash. It is more important that users know they
are dealing with a set than which subclass:

  Class.new(Set)[]
  # this does: Set[]
  # not: #<Class:0x00000c21c78699e0>[]

This inspect change breaks the power_assert bundled gem tests, so
add power_assert to TEST_BUNDLED_GEMS_ALLOW_FAILURES in the workflows.

Implements [Feature #21389]

.github/workflows/bundled_gems.yml

@@ -104,7 +104,7 @@ jobs:
         timeout-minutes: 30
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor,power_assert'
         if: ${{ steps.diff.outputs.gems }}
 
       - name: Commit

.github/workflows/macos.yml

@@ -146,7 +146,7 @@ jobs:
         timeout-minutes: 60
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor,power_assert'
           PRECHECK_BUNDLED_GEMS: 'no'
           LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
           LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}

.github/workflows/modgc.yml

@@ -153,7 +153,7 @@ jobs:
         timeout-minutes: ${{ matrix.gc.timeout || 40 }}
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor,power_assert'
           PRECHECK_BUNDLED_GEMS: 'no'
           LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
           LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}

.github/workflows/parse_y.yml

@@ -87,7 +87,7 @@ jobs:
           EXCLUDES: '../src/test/.excludes-parsey'
           RUN_OPTS: ${{ matrix.run_opts || '--parser=parse.y' }}
           SPECOPTS: ${{ matrix.specopts || '-T --parser=parse.y' }}
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor,power_assert'
 
       - uses: ./.github/actions/slack
         with:

.github/workflows/ubuntu.yml

@@ -133,7 +133,7 @@ jobs:
         timeout-minutes: ${{ matrix.timeout || 40 }}
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor,power_assert'
           PRECHECK_BUNDLED_GEMS: 'no'
           LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
           LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}

.github/workflows/yjit-macos.yml

@@ -153,7 +153,7 @@ jobs:
         timeout-minutes: 60
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor,power_assert'
           SYNTAX_SUGGEST_TIMEOUT: '5'
           PRECHECK_BUNDLED_GEMS: 'no'
           LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}

.github/workflows/yjit-ubuntu.yml

@@ -201,7 +201,7 @@ jobs:
         timeout-minutes: 90
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,rbs,repl_type_completor,power_assert'
           PRECHECK_BUNDLED_GEMS: 'no'
           SYNTAX_SUGGEST_TIMEOUT: '5'
           YJIT_BINDGEN_DIFF_OPTS: '--exit-code'

.github/workflows/zjit-macos.yml

@@ -150,7 +150,7 @@ jobs:
         timeout-minutes: 60
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,power_assert'
           SYNTAX_SUGGEST_TIMEOUT: '5'
           PRECHECK_BUNDLED_GEMS: 'no'
           TESTS: ${{ matrix.tests }}

.github/workflows/zjit-ubuntu.yml

@@ -172,7 +172,7 @@ jobs:
         timeout-minutes: 90
         env:
           RUBY_TESTOPTS: '-q --tty=no'
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof,power_assert'
           PRECHECK_BUNDLED_GEMS: 'no'
           SYNTAX_SUGGEST_TIMEOUT: '5'
           ZJIT_BINDGEN_DIFF_OPTS: '--exit-code'

set.c

@@ -537,7 +537,7 @@ static int
 set_inspect_i(st_data_t key, st_data_t arg)
 {
     VALUE str = (VALUE)arg;
-    if (RSTRING_LEN(str) > 8) {
+    if (RSTRING_LEN(str) > 4) {
         rb_str_buf_cat_ascii(str, ", ");
     }
     rb_str_buf_append(str, rb_inspect((VALUE)key));
@@ -550,10 +550,10 @@ set_inspect(VALUE set, VALUE dummy, int recur)
 {
     VALUE str;
 
-    if (recur) return rb_usascii_str_new2("#<Set: {...}>");
-    str = rb_str_buf_new2("#<Set: {");
+    if (recur) return rb_usascii_str_new2("Set[...]");
+    str = rb_str_buf_new2("Set[");
     set_iter(set, set_inspect_i, str);
-    rb_str_buf_cat2(str, "}>");
+    rb_str_buf_cat2(str, "]");
 
     return str;
 }

spec/ruby/core/enumerable/to_set_spec.rb

@@ -30,9 +30,9 @@ describe "Enumerable#to_set" do
 
   it "does not need explicit `require 'set'`" do
     output = ruby_exe(<<~RUBY, options: '--disable-gems', args: '2>&1')
-      puts [1, 2, 3].to_set
+      puts [1, 2, 3].to_set.to_a.inspect
     RUBY
 
-    output.chomp.should == "#<Set: {1, 2, 3}>"
+    output.chomp.should == "[1, 2, 3]"
   end
 end

spec/ruby/core/set/compare_by_identity_spec.rb

@@ -95,7 +95,7 @@ describe "Set#compare_by_identity" do
       set = Set.new.freeze
       -> {
         set.compare_by_identity
-      }.should raise_error(FrozenError, "can't modify frozen Set: #<Set: {}>")
+      }.should raise_error(FrozenError, /can't modify frozen Set: (#<)?Set(\[|: {)[\]}]>?/)
     end
   end
 

spec/ruby/core/set/set_spec.rb

@@ -3,8 +3,8 @@ require_relative '../../spec_helper'
 describe 'Set' do
   it 'is available without explicit requiring' do
     output = ruby_exe(<<~RUBY, options: '--disable-gems', args: '2>&1')
-      puts Set.new([1, 2, 3])
+      puts Set.new([1, 2, 3]).to_a.inspect
     RUBY
-    output.chomp.should == "#<Set: {1, 2, 3}>"
+    output.chomp.should == "[1, 2, 3]"
   end
 end

spec/ruby/core/set/shared/inspect.rb

@@ -7,19 +7,39 @@ describe :set_inspect, shared: true do
     Set[:a, "b", Set[?c]].send(@method).should be_kind_of(String)
   end
 
-  it "does include the elements of the set" do
-    Set["1"].send(@method).should == '#<Set: {"1"}>'
+  ruby_version_is "3.5" do
+    it "does include the elements of the set" do
+      Set["1"].send(@method).should == 'Set["1"]'
+    end
+  end
+
+  ruby_version_is ""..."3.5" do
+    it "does include the elements of the set" do
+      Set["1"].send(@method).should == '#<Set: {"1"}>'
+    end
   end
 
   it "puts spaces between the elements" do
     Set["1", "2"].send(@method).should include('", "')
   end
 
-  it "correctly handles cyclic-references" do
-    set1 = Set[]
-    set2 = Set[set1]
-    set1 << set2
-    set1.send(@method).should be_kind_of(String)
-    set1.send(@method).should include("#<Set: {...}>")
+  ruby_version_is "3.5" do
+    it "correctly handles cyclic-references" do
+      set1 = Set[]
+      set2 = Set[set1]
+      set1 << set2
+      set1.send(@method).should be_kind_of(String)
+      set1.send(@method).should include("Set[...]")
+    end
+  end
+
+  ruby_version_is ""..."3.5" do
+    it "correctly handles cyclic-references" do
+      set1 = Set[]
+      set2 = Set[set1]
+      set1 << set2
+      set1.send(@method).should be_kind_of(String)
+      set1.send(@method).should include("#<Set: {...}>")
+    end
   end
 end

test/ruby/test_set.rb

@@ -839,24 +839,24 @@ class TC_Set < Test::Unit::TestCase
 
   def test_inspect
     set1 = Set[1, 2]
-    assert_equal('#<Set: {1, 2}>', set1.inspect)
+    assert_equal('Set[1, 2]', set1.inspect)
 
     set2 = Set[Set[0], 1, 2, set1]
-    assert_equal('#<Set: {#<Set: {0}>, 1, 2, #<Set: {1, 2}>}>', set2.inspect)
+    assert_equal('Set[Set[0], 1, 2, Set[1, 2]]', set2.inspect)
 
     set1.add(set2)
-    assert_equal('#<Set: {#<Set: {0}>, 1, 2, #<Set: {1, 2, #<Set: {...}>}>}>', set2.inspect)
+    assert_equal('Set[Set[0], 1, 2, Set[1, 2, Set[...]]]', set2.inspect)
   end
 
   def test_to_s
     set1 = Set[1, 2]
-    assert_equal('#<Set: {1, 2}>', set1.to_s)
+    assert_equal('Set[1, 2]', set1.to_s)
 
     set2 = Set[Set[0], 1, 2, set1]
-    assert_equal('#<Set: {#<Set: {0}>, 1, 2, #<Set: {1, 2}>}>', set2.to_s)
+    assert_equal('Set[Set[0], 1, 2, Set[1, 2]]', set2.to_s)
 
     set1.add(set2)
-    assert_equal('#<Set: {#<Set: {0}>, 1, 2, #<Set: {1, 2, #<Set: {...}>}>}>', set2.to_s)
+    assert_equal('Set[Set[0], 1, 2, Set[1, 2, Set[...]]]', set2.to_s)
   end
 
   def test_compare_by_identity

tool/test-bundled-gems.rb

@@ -10,7 +10,7 @@ github_actions = ENV["GITHUB_ACTIONS"] == "true"
 
 allowed_failures = ENV['TEST_BUNDLED_GEMS_ALLOW_FAILURES'] || ''
 if RUBY_PLATFORM =~ /mswin|mingw/
-  allowed_failures = [allowed_failures, "rbs,debug,irb"].join(',')
+  allowed_failures = [allowed_failures, "rbs,debug,irb,power_assert"].join(',')
 end
 allowed_failures = allowed_failures.split(',').uniq.reject(&:empty?)