Use -- for bottles.

Library/Homebrew/dev-cmd/bottle.rb

@@ -391,7 +391,7 @@ module Homebrew
           "rebuild" => bottle.rebuild,
           "tags" => {
             tag => {
-              "filename" => filename.to_s,
+              "filename" => filename.bintray,
               "sha256" => sha256,
             },
           },
@@ -402,7 +402,7 @@ module Homebrew
         },
       },
     }
-    File.open("#{filename.prefix}.bottle.json", "w") do |file|
+    File.open(filename.json, "w") do |file|
       file.write JSON.generate json
     end
   end

Library/Homebrew/formula.rb

@@ -1617,7 +1617,7 @@ class Formula
       bottle_spec.collector.keys.each do |os|
         checksum = bottle_spec.collector[os]
         bottle_info["files"][os] = {
-          "url" => "#{bottle_spec.root_url}/#{Bottle::Filename.create(self, os, bottle_spec.rebuild)}",
+          "url" => "#{bottle_spec.root_url}/#{Bottle::Filename.create(self, os, bottle_spec.rebuild).bintray}",
           checksum.hash_type.to_s => checksum.hexdigest,
         }
       end

Library/Homebrew/software_spec.rb

@@ -259,17 +259,21 @@ class Bottle
     end
 
     def to_s
-      prefix + suffix
+      "#{name}--#{version}#{extname}"
     end
     alias to_str to_s
 
-    def prefix
-      "#{name}-#{version}.#{tag}"
+    def json
+      "#{name}--#{version}.#{tag}.bottle.json"
     end
 
-    def suffix
+    def bintray
+      "#{name}-#{version}#{extname}"
+    end
+
+    def extname
       s = rebuild.positive? ? ".#{rebuild}" : ""
-      ".bottle#{s}.tar.gz"
+      ".#{tag}.bottle#{s}.tar.gz"
     end
   end
 
@@ -290,7 +294,7 @@ class Bottle
     checksum, tag = spec.checksum_for(Utils::Bottles.tag)
 
     filename = Filename.create(formula, tag, spec.rebuild)
-    @resource.url(build_url(spec.root_url, filename),
+    @resource.url(build_url(spec.root_url, filename.bintray),
                   select_download_strategy(spec.root_url_specs))
     @resource.version = formula.pkg_version
     @resource.checksum = checksum

Library/Homebrew/test/bottle_filename_spec.rb

@@ -2,36 +2,53 @@ require "formula"
 require "software_spec"
 
 describe Bottle::Filename do
-  specify "#prefix" do
-    expect(described_class.new("foo", "1.0", :tag, 0).prefix)
-      .to eq("foo-1.0.tag")
+  subject { described_class.new(name, version, tag, rebuild) }
+
+  let(:name) { "foo" }
+  let(:version) { "1.0" }
+  let(:tag) { :tag }
+  let(:rebuild) { 0 }
+
+  describe "#extname" do
+    its(:extname) { is_expected.to eq ".tag.bottle.tar.gz" }
+
+    context "when rebuild is 0" do
+      its(:extname) { is_expected.to eq ".tag.bottle.tar.gz" }
     end
 
-  specify "#suffix" do
-    expect(described_class.new("foo", "1.0", :tag, 0).suffix)
-      .to eq(".bottle.tar.gz")
-
-    expect(described_class.new("foo", "1.0", :tag, 1).suffix)
-      .to eq(".bottle.1.tar.gz")
+    context "when rebuild is 1" do
+      let(:rebuild) { 1 }
+      its(:extname) { is_expected.to eq ".tag.bottle.1.tar.gz" }
+    end
   end
 
-  specify "#to_s and #to_str" do
-    expected = "foo-1.0.tag.bottle.tar.gz"
-
-    expect(described_class.new("foo", "1.0", :tag, 0).to_s)
-      .to eq(expected)
-
-    expect(described_class.new("foo", "1.0", :tag, 0).to_str)
-      .to eq(expected)
+  describe "#to_s and #to_str" do
+    its(:to_s) { is_expected.to eq "foo--1.0.tag.bottle.tar.gz" }
+    its(:to_str) { is_expected.to eq "foo--1.0.tag.bottle.tar.gz" }
   end
 
-  specify "::create" do
-    f = formula do
+  describe "#bintray" do
+    its(:bintray) { is_expected.to eq "foo-1.0.tag.bottle.tar.gz" }
+  end
+
+  describe "#json" do
+    its(:json) { is_expected.to eq "foo--1.0.tag.bottle.json" }
+
+    context "when rebuild is 1" do
+      its(:json) { is_expected.to eq "foo--1.0.tag.bottle.json" }
+    end
+  end
+
+  describe "::create" do
+    subject { described_class.create(f, :tag, 0) }
+
+    let(:f) {
+      formula do
         url "https://example.com/foo.tar.gz"
         version "1.0"
       end
+    }
 
-    expect(described_class.create(f, :tag, 0).to_s)
-      .to eq("formula_name-1.0.tag.bottle.tar.gz")
+    its(:to_s) { is_expected.to eq "formula_name--1.0.tag.bottle.tar.gz" }
   end
 end

Library/Homebrew/test/dev-cmd/bottle_spec.rb

@@ -21,11 +21,11 @@ describe "brew bottle", :integration_test do
       end
 
       expect { brew "bottle", "--no-rebuild", "testball" }
-        .to output(/testball-0\.1.*\.bottle\.tar\.gz/).to_stdout
+        .to output(/testball--0\.1.*\.bottle\.tar\.gz/).to_stdout
         .and not_to_output.to_stderr
         .and be_a_success
     ensure
-      FileUtils.rm_f Dir.glob("testball-0.1*.bottle.tar.gz")
+      FileUtils.rm_f Dir.glob("testball--0.1*.bottle.tar.gz")
     end
   end
 end