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author | Jeremy Evans <code@jeremyevans.net> | 2020-05-28 14:59:11 -0700 |
---|---|---|
committer | Jeremy Evans <code@jeremyevans.net> | 2020-06-18 08:19:33 -0700 |
commit | aae8223c7076483f1f1641181088790b2f3a66dd (patch) | |
tree | 91498384f79e4d4ec71ef601e903ee794c081ceb /spec/ruby/language | |
parent | 6439c939db2da90501dfd5a03a43a7506cd94f56 (diff) | |
download | ruby-aae8223c7076483f1f1641181088790b2f3a66dd.tar.gz |
Dup splat array in certain cases where there is a block argument
This makes:
```ruby
args = [1, 2, -> {}]; foo(*args, &args.pop)
```
call `foo` with 1, 2, and the lambda, in addition to passing the
lambda as a block. This is different from the previous behavior,
which passed the lambda as a block but not as a regular argument,
which goes against the expected left-to-right evaluation order.
This is how Ruby already compiled arguments if using leading
arguments, trailing arguments, or keywords in the same call.
This works by disabling the optimization that skipped duplicating
the array during the splat (splatarray instruction argument
switches from false to true). In the above example, the splat
call duplicates the array. I've tested and cases where a
local variable or symbol are used do not duplicate the array,
so I don't expect this to decrease the performance of most Ruby
programs. However, programs such as:
```ruby
foo(*args, &bar)
```
could see a decrease in performance, if `bar` is a method call
and not a local variable.
This is not a perfect solution, there are ways to get around
this:
```ruby
args = Struct.new(:a).new([:x, :y])
def args.to_a; a; end
def args.to_proc; a.pop; ->{}; end
foo(*args, &args)
# calls foo with 1 argument (:x)
# not 2 arguments (:x and :y)
```
A perfect solution would require completely disabling the
optimization.
Fixes [Bug #16504]
Fixes [Bug #16500]
Diffstat (limited to 'spec/ruby/language')
-rw-r--r-- | spec/ruby/language/send_spec.rb | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/spec/ruby/language/send_spec.rb b/spec/ruby/language/send_spec.rb index c56d5e8c26..17381166dc 100644 --- a/spec/ruby/language/send_spec.rb +++ b/spec/ruby/language/send_spec.rb @@ -421,18 +421,36 @@ describe "Invoking a method" do specs.rest_len(0,*a,4,*5,6,7,*c,-1).should == 11 end - it "expands the Array elements from the splat after executing the arguments and block if no other arguments follow the splat" do - def self.m(*args, &block) - [args, block] + ruby_version_is ""..."2.8" do + it "expands the Array elements from the splat after executing the arguments and block if no other arguments follow the splat" do + def self.m(*args, &block) + [args, block] + end + + args = [1, nil] + m(*args, &args.pop).should == [[1], nil] + + args = [1, nil] + order = [] + m(*(order << :args; args), &(order << :block; args.pop)).should == [[1], nil] + order.should == [:args, :block] end + end - args = [1, nil] - m(*args, &args.pop).should == [[1], nil] + ruby_version_is "2.8" do + it "expands the Array elements from the splat before applying block argument operations" do + def self.m(*args, &block) + [args, block] + end - args = [1, nil] - order = [] - m(*(order << :args; args), &(order << :block; args.pop)).should == [[1], nil] - order.should == [:args, :block] + args = [1, nil] + m(*args, &args.pop).should == [[1, nil], nil] + + args = [1, nil] + order = [] + m(*(order << :args; args), &(order << :block; args.pop)).should == [[1, nil], nil] + order.should == [:args, :block] + end end it "evaluates the splatted arguments before the block if there are other arguments after the splat" do |