Ensure test suite is compatible with --frozen-string-literal

As preparation for https://bugs.ruby-lang.org/issues/20205
making sure the test suite is compatible with frozen string
literals is making things easier.

basictest/test.rb

@@ -879,7 +879,7 @@ def r(val); a,b,*c = *yield(); test_ok([a,b,c] == val, 2); end
 test_ok($x == [7,5,3,2,1])
 
 # split test
-$x = "The Book of Mormon"
+$x = +"The Book of Mormon"
 test_ok($x.split(//).reverse!.join == $x.reverse)
 test_ok($x.reverse == $x.reverse!)
 test_ok("1 byte string".split(//).reverse.join(":") == "g:n:i:r:t:s: :e:t:y:b: :1")
@@ -1643,7 +1643,7 @@ def shift_test(a)
 test_ok(/(\s+\d+){2}/ =~ " 1 2" && $& == " 1 2")
 test_ok(/(?:\s+\d+){2}/ =~ " 1 2" && $& == " 1 2")
 
-$x = <<END;
+$x = +<<END;
 ABCD
 ABCD
 END
@@ -1682,12 +1682,12 @@ def shift_test(a)
 test_ok(?\C-a == "\1")
 test_ok(?\M-a == "\341")
 test_ok(?\M-\C-a == "\201")
-test_ok("a".upcase![0] == ?A)
-test_ok("A".downcase![0] == ?a)
-test_ok("abc".tr!("a-z", "A-Z") == "ABC")
-test_ok("aabbcccc".tr_s!("a-z", "A-Z") == "ABC")
-test_ok("abcc".squeeze!("a-z") == "abc")
-test_ok("abcd".delete!("bc") == "ad")
+test_ok("a".dup.upcase![0] == ?A)
+test_ok("A".dup.downcase![0] == ?a)
+test_ok("abc".dup.tr!("a-z", "A-Z") == "ABC")
+test_ok("aabbcccc".dup.tr_s!("a-z", "A-Z") == "ABC")
+test_ok("abcc".dup.squeeze!("a-z") == "abc")
+test_ok("abcd".dup.delete!("bc") == "ad")
 
 $x = "abcdef"
 $y = [ ?a, ?b, ?c, ?d, ?e, ?f ]
@@ -1700,7 +1700,7 @@ def shift_test(a)
 }
 test_ok(!$bad)
 
-s = "a string"
+s = +"a string"
 s[0..s.size]="another string"
 test_ok(s == "another string")
 

bootstraptest/runner.rb

@@ -548,10 +548,10 @@ def get_result_string(opt = '', **argh)
     end
   end
 
-  def make_srcfile(frozen_string_literal: nil)
+  def make_srcfile(frozen_string_literal: true)
     filename = "bootstraptest.#{self.path}_#{self.lineno}_#{self.id}.rb"
     File.open(filename, 'w') {|f|
-      f.puts "#frozen_string_literal:true" if frozen_string_literal
+      f.puts "#frozen_string_literal:#{frozen_string_literal}" unless frozen_string_literal.nil?
       if $stress
         f.puts "GC.stress = true" if $stress
       else
@@ -572,9 +572,9 @@ def add_assertion src, pr
   Assertion.new(src, path, lineno, pr)
 end
 
-def assert_equal(expected, testsrc, message = '', opt = '', **argh)
+def assert_equal(expected, testsrc, message = '', opt = '', **kwargs)
   add_assertion testsrc, -> as do
-    as.assert_check(message, opt, **argh) {|result|
+    as.assert_check(message, opt, **kwargs) {|result|
       if expected == result
         nil
       else
@@ -585,9 +585,9 @@ def assert_equal(expected, testsrc, message = '', opt = '', **argh)
   end
 end
 
-def assert_match(expected_pattern, testsrc, message = '')
+def assert_match(expected_pattern, testsrc, message = '', **argh)
   add_assertion testsrc, -> as do
-    as.assert_check(message) {|result|
+    as.assert_check(message, **argh) {|result|
       if expected_pattern =~ result
         nil
       else

bootstraptest/test_flow.rb

@@ -363,7 +363,7 @@ class C
 ; $a << 8
 ; rescue Exception; $a << 99; end; $a}
 assert_equal %q{[1, 2, 6, 3, 5, 7, 8]}, %q{$a = []; begin;  ; $a << 1
-  o = "test"; $a << 2
+  o = "test".dup; $a << 2
   def o.test(a); $a << 3
     return a; $a << 4
   ensure; $a << 5

bootstraptest/test_insns.rb

@@ -354,7 +354,7 @@ class X; def != other; true; end; end
   [ 'opt_ge', %q{ +0.0.next_float >= 0.0 }, ],
   [ 'opt_ge', %q{              ?z >= ?a }, ],
 
-  [ 'opt_ltlt', %q{  '' << 'true' }, ],
+  [ 'opt_ltlt', %q{  +'' << 'true' }, ],
   [ 'opt_ltlt', %q{ ([] << 'true').join }, ],
   [ 'opt_ltlt', %q{ (1 << 31) == 2147483648 }, ],
 
@@ -363,7 +363,7 @@ class X; def != other; true; end; end
   [ 'opt_aref', %q{ 'true'[0] == ?t }, ],
   [ 'opt_aset', %q{ [][0] = true }, ],
   [ 'opt_aset', %q{ {}[0] = true }, ],
-  [ 'opt_aset', %q{ x = 'frue'; x[0] = 't'; x }, ],
+  [ 'opt_aset', %q{ x = +'frue'; x[0] = 't'; x }, ],
   [ 'opt_aset', <<-'},', ], # {
     # opt_aref / opt_aset mixup situation
     class X; def x; {}; end; end

bootstraptest/test_jump.rb

@@ -292,7 +292,7 @@ class << self
       end
     end
   end
-  s = "foo"
+  s = +"foo"
   s.return_eigenclass == class << s; self; end
 }, '[ruby-core:21379]'
 

bootstraptest/test_ractor.rb

@@ -628,7 +628,7 @@ def test n
 }
 
 # send shareable and unshareable objects
-assert_equal "ok", %q{
+assert_equal "ok", <<~'RUBY', frozen_string_literal: false
   echo_ractor = Ractor.new do
     loop do
       v = Ractor.receive
@@ -695,10 +695,10 @@ module M; end
   else
     results.inspect
   end
-}
+RUBY
 
 # frozen Objects are shareable
-assert_equal [false, true, false].inspect, %q{
+assert_equal [false, true, false].inspect, <<~'RUBY', frozen_string_literal: false
   class C
     def initialize freeze
       @a = 1
@@ -721,11 +721,11 @@ def check obj1
   results << check(C.new(true))         # false
   results << check(C.new(true).freeze)  # true
   results << check(C.new(false).freeze) # false
-}
+RUBY
 
 # move example2: String
 # touching moved object causes an error
-assert_equal 'hello world', %q{
+assert_equal 'hello world', <<~'RUBY', frozen_string_literal: false
   # move
   r = Ractor.new do
     obj = Ractor.receive
@@ -743,7 +743,7 @@ def check obj1
   else
     raise 'unreachable'
   end
-}
+RUBY
 
 # move example2: Array
 assert_equal '[0, 1]', %q{
@@ -946,7 +946,7 @@ def ractor_local_globals
 }
 
 # ivar in shareable-objects are not allowed to access from non-main Ractor
-assert_equal "can not get unshareable values from instance variables of classes/modules from non-main Ractors", %q{
+assert_equal "can not get unshareable values from instance variables of classes/modules from non-main Ractors", <<~'RUBY', frozen_string_literal: false
   class C
     @iv = 'str'
   end
@@ -957,13 +957,12 @@ class C
     end
   end
 
-
   begin
     r.take
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+RUBY
 
 # ivar in shareable-objects are not allowed to access from non-main Ractor
 assert_equal 'can not access instance variables of shareable objects from non-main Ractors', %q{
@@ -1150,7 +1149,7 @@ def self.cv
 }
 
 # Getting non-shareable objects via constants by other Ractors is not allowed
-assert_equal 'can not access non-shareable objects in constant C::CONST by non-main Ractor.', %q{
+assert_equal 'can not access non-shareable objects in constant C::CONST by non-main Ractor.', <<~'RUBY', frozen_string_literal: false
   class C
     CONST = 'str'
   end
@@ -1162,10 +1161,10 @@ class C
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+  RUBY
 
 # Constant cache should care about non-sharable constants
-assert_equal "can not access non-shareable objects in constant Object::STR by non-main Ractor.", %q{
+assert_equal "can not access non-shareable objects in constant Object::STR by non-main Ractor.", <<~'RUBY', frozen_string_literal: false
   STR = "hello"
   def str; STR; end
   s = str() # fill const cache
@@ -1174,10 +1173,10 @@ def str; STR; end
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+RUBY
 
 # Setting non-shareable objects into constants by other Ractors is not allowed
-assert_equal 'can not set constants with non-shareable objects by non-main Ractors', %q{
+assert_equal 'can not set constants with non-shareable objects by non-main Ractors', <<~'RUBY', frozen_string_literal: false
   class C
   end
   r = Ractor.new do
@@ -1188,7 +1187,7 @@ class C
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+RUBY
 
 # define_method is not allowed
 assert_equal "defined with an un-shareable Proc in a different Ractor", %q{
@@ -1241,7 +1240,7 @@ class C
 }
 
 # ObjectSpace._id2ref can not handle unshareable objects with Ractors
-assert_equal 'ok', %q{
+assert_equal 'ok', <<~'RUBY', frozen_string_literal: false
   s = 'hello'
 
   Ractor.new s.object_id do |id ;s|
@@ -1251,10 +1250,10 @@ class C
       :ok
     end
   end.take
-}
+RUBY
 
 # Ractor.make_shareable(obj)
-assert_equal 'true', %q{
+assert_equal 'true', <<~'RUBY', frozen_string_literal: false
   class C
     def initialize
       @a = 'foo'
@@ -1325,7 +1324,7 @@ def /(other)
   }
 
   Ractor.shareable?(a)
-}
+RUBY
 
 # Ractor.make_shareable(obj) doesn't freeze shareable objects
 assert_equal 'true', %q{
@@ -1422,14 +1421,14 @@ class C
 }
 
 # TracePoint with normal Proc should be Ractor local
-assert_equal '[6, 10]', %q{
+assert_equal '[7, 11]', %q{
   rs = []
   TracePoint.new(:line){|tp| rs << tp.lineno if tp.path == __FILE__}.enable do
-    Ractor.new{ # line 4
+    Ractor.new{ # line 5
       a = 1
       b = 2
     }.take
-    c = 3       # line 8
+    c = 3       # line 9
   end
   rs
 }
@@ -1503,7 +1502,7 @@ class C
   2.times.map{
     Ractor.new do
       #{n}.times do
-        obj = ''
+        obj = +''
         obj.instance_variable_set("@a", 1)
         obj.instance_variable_set("@b", 1)
         obj.instance_variable_set("@c", 1)
@@ -1662,7 +1661,7 @@ class C8; def self.foo = 17; end
   Warning[:experimental] = $VERBOSE = true
   STDERR.reopen(STDOUT)
   eval("Ractor.new{}.take", nil, "test_ractor.rb", 1)
-}
+}, frozen_string_literal: false
 
 # check moved object
 assert_equal 'ok', %q{

bootstraptest/test_syntax.rb

@@ -629,7 +629,7 @@ class << (ary=[]); def []; 0; end; def []=(x); super(0,x);end;end; ary[]+=1
 
 assert_match /invalid multibyte char/, %q{
   $stderr = STDOUT
-  eval("\"\xf0".force_encoding("utf-8"))
+  eval("\"\xf0".dup.force_encoding("utf-8"))
 }, '[ruby-dev:32429]'
 
 # method ! and !=

bootstraptest/test_yjit.rb

@@ -185,7 +185,7 @@ def carray(iter)
   end
 
   def cstring(iter)
-    string = ""
+    string = "".dup
     string.sum(iter.times { def string.sum(_) = :sum })
   end
 
@@ -1250,7 +1250,7 @@ def foo
 # Test polymorphic getinstancevariable. T_OBJECT -> T_STRING
 assert_equal 'ok', %q{
   @hello = @h1 = @h2 = @h3 = @h4 = 'ok'
-  str = ""
+  str = +""
   str.instance_variable_set(:@hello, 'ok')
 
   public def get
@@ -1395,7 +1395,7 @@ def index(obj, idx)
 }
 
 # Test default value block for Hash with opt_aref_with
-assert_equal "false", %q{
+assert_equal "false", <<~RUBY, frozen_string_literal: false
   def index_with_string(h)
     h["foo"]
   end
@@ -1404,7 +1404,7 @@ def index_with_string(h)
 
   index_with_string(h)
   index_with_string(h)
-}
+RUBY
 
 # A regression test for making sure cfp->sp is proper when
 # hitting stubs. See :stub-sp-flush:
@@ -1904,7 +1904,7 @@ def make_str(foo)
 }
 
 # Test that String unary plus returns the same object ID for an unfrozen string.
-assert_equal 'true', %q{
+assert_equal 'true', <<~RUBY, frozen_string_literal: false
   def jittable_method
     str = "bar"
 
@@ -1914,7 +1914,7 @@ def jittable_method
     uplus_str.object_id == old_obj_id
   end
   jittable_method
-}
+RUBY
 
 # Test that String unary plus returns a different unfrozen string when given a frozen string
 assert_equal 'false', %q{
@@ -2048,7 +2048,7 @@ def getbyte(s, i)
 
 # Basic test for String#setbyte
 assert_equal 'AoZ', %q{
-  s = "foo"
+  s = +"foo"
   s.setbyte(0, 65)
   s.setbyte(-1, 90)
   s
@@ -2091,7 +2091,7 @@ def to_int
     0
   end
 
-  def ccall = "a".setbyte(self, 98)
+  def ccall = "a".dup.setbyte(self, 98)
   ccall
 
   @caller.first.split("'").last
@@ -4167,7 +4167,7 @@ def foo
 assert_equal 'Hello World', %q{
   def bar
     args = ["Hello "]
-    greeting = "World"
+    greeting = +"World"
     greeting.insert(0, *args)
     greeting
   end