From 33a2f410afa1629fff2c435eaf885120db137368 Mon Sep 17 00:00:00 2001
From: Ruoyu Zhong <zhongruoyu@outlook.com>
Date: Fri, 22 Aug 2025 01:59:54 +0800
Subject: [PATCH 1/2] cli/parser: convert switch env values to boolean

Since switch values are boolean, we should be returning the environment
variable's presence instead of its string value.

Fixes #20531.
---
 Library/Homebrew/cli/parser.rb           | 3 ++-
 Library/Homebrew/test/cli/parser_spec.rb | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Library/Homebrew/cli/parser.rb b/Library/Homebrew/cli/parser.rb
index 7ffe3e0c72..b464755e05 100644
--- a/Library/Homebrew/cli/parser.rb
+++ b/Library/Homebrew/cli/parser.rb
@@ -231,7 +231,8 @@ module Homebrew
         end
 
         env_value = value_for_env(env)
-        set_switch(*names, value: env_value, from: :env) unless env_value.nil?
+        value = env_value&.present?
+        set_switch(*names, value:, from: :env) unless value.nil?
       end
       alias switch_option switch
 
diff --git a/Library/Homebrew/test/cli/parser_spec.rb b/Library/Homebrew/test/cli/parser_spec.rb
index d4d5edb786..c2b23fd81c 100644
--- a/Library/Homebrew/test/cli/parser_spec.rb
+++ b/Library/Homebrew/test/cli/parser_spec.rb
@@ -10,12 +10,15 @@ RSpec.describe Homebrew::CLI::Parser do
       described_class.new(Cmd) do
         switch "--more-verbose", description: "Flag for higher verbosity"
         switch "--pry", env: :pry
+        switch "--bar", env: :bar
         switch "--hidden", hidden: true
       end
     end
 
     before do
       allow(Homebrew::EnvConfig).to receive(:pry?).and_return(true)
+      allow(ENV).to receive(:fetch).and_call_original
+      allow(ENV).to receive(:fetch).with("HOMEBREW_BAR", nil).and_return("1")
     end
 
     context "when using binary options" do
@@ -113,6 +116,7 @@ RSpec.describe Homebrew::CLI::Parser do
     it "maps environment var to an option" do
       args = parser.parse([])
       expect(args.pry?).to be true
+      expect(args.bar?).to be true
     end
   end
 

From 625a6c08ebbeb4408432faddc93f11d95b73ff8f Mon Sep 17 00:00:00 2001
From: Ruoyu Zhong <zhongruoyu@outlook.com>
Date: Fri, 22 Aug 2025 02:04:55 +0800
Subject: [PATCH 2/2] test/cli/parser: add one more test

---
 Library/Homebrew/test/cli/parser_spec.rb | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Library/Homebrew/test/cli/parser_spec.rb b/Library/Homebrew/test/cli/parser_spec.rb
index c2b23fd81c..33497a3685 100644
--- a/Library/Homebrew/test/cli/parser_spec.rb
+++ b/Library/Homebrew/test/cli/parser_spec.rb
@@ -10,6 +10,7 @@ RSpec.describe Homebrew::CLI::Parser do
       described_class.new(Cmd) do
         switch "--more-verbose", description: "Flag for higher verbosity"
         switch "--pry", env: :pry
+        switch "--foo", env: :foo
         switch "--bar", env: :bar
         switch "--hidden", hidden: true
       end
@@ -18,6 +19,7 @@ RSpec.describe Homebrew::CLI::Parser do
     before do
       allow(Homebrew::EnvConfig).to receive(:pry?).and_return(true)
       allow(ENV).to receive(:fetch).and_call_original
+      allow(ENV).to receive(:fetch).with("HOMEBREW_FOO", nil).and_return("")
       allow(ENV).to receive(:fetch).with("HOMEBREW_BAR", nil).and_return("1")
     end
 
@@ -116,6 +118,7 @@ RSpec.describe Homebrew::CLI::Parser do
     it "maps environment var to an option" do
       args = parser.parse([])
       expect(args.pry?).to be true
+      expect(args.foo?).to be false
       expect(args.bar?).to be true
     end
   end