2 files changed, 64 insertions, 0 deletions

diff --git a/lib/bundler/dsl.rb b/lib/bundler/dsl.rb
index 7a4fc3909e..2f9d1f9054 100644
--- a/lib/bundler/dsl.rb
+++ b/lib/bundler/dsl.rb
@@ -185,12 +185,22 @@ module Bundler
       with_source(git_source) { yield }
     end
 
+    SUPPORTED_OVERRIDE_FIELDS = [:version].freeze
+    SUPPORTED_OVERRIDE_SYMBOL_OPERATIONS = [:ignore_upper].freeze
+
     def override(target, **operations)
+      validate_override_target!(target)
+
       if target == :all && operations.key?(:version)
         raise ArgumentError, "`override :all, version:` is not allowed; version requirements are per-gem"
       end
 
       operations.each do |field, operation|
+        validate_override_field!(field)
+        validate_override_operation!(operation)
+      end
+
+      operations.each do |field, operation|
         @overrides << Override.new(target, field, operation)
       end
     end
@@ -257,6 +267,29 @@ module Bundler
 
     private
 
+    def validate_override_target!(target)
+      return if target == :all
+      return if target.is_a?(String)
+      raise ArgumentError, "override target must be :all or a gem name string, got #{target.inspect}"
+    end
+
+    def validate_override_field!(field)
+      return if SUPPORTED_OVERRIDE_FIELDS.include?(field)
+      raise ArgumentError, "unsupported override field `#{field}:`; only `version:` is currently supported"
+    end
+
+    def validate_override_operation!(operation)
+      case operation
+      when String, nil
+        # ok
+      when Symbol
+        return if SUPPORTED_OVERRIDE_SYMBOL_OPERATIONS.include?(operation)
+        raise ArgumentError, "unsupported override operation: #{operation.inspect}"
+      else
+        raise ArgumentError, "override operation must be a String, Symbol, or nil, got #{operation.inspect}"
+      end
+    end
+
     def add_dependency(name, version = nil, options = {})
       options["gemfile"] = @gemfile
       options["source"] ||= @source
diff --git a/spec/bundler/bundler/dsl_spec.rb b/spec/bundler/bundler/dsl_spec.rb
index d5e5f830ce..86bcb3be8d 100644
--- a/spec/bundler/bundler/dsl_spec.rb
+++ b/spec/bundler/bundler/dsl_spec.rb
@@ -416,5 +416,36 @@ RSpec.describe Bundler::Dsl do
       end.to raise_error(ArgumentError)
       expect(subject.overrides).to eq([])
     end
+
+    it "raises ArgumentError when target is neither :all nor a string" do
+      expect do
+        subject.override(:rails, version: ">= 8.0")
+      end.to raise_error(ArgumentError, /target must be :all or a gem name string/)
+    end
+
+    it "raises ArgumentError for an unsupported field" do
+      expect do
+        subject.override("rails", required_ruby_version: :ignore_upper)
+      end.to raise_error(ArgumentError, /unsupported override field `required_ruby_version:`/)
+    end
+
+    it "raises ArgumentError for a non-string, non-symbol, non-nil operation" do
+      expect do
+        subject.override("rails", version: 42)
+      end.to raise_error(ArgumentError, /override operation must be a String, Symbol, or nil/)
+    end
+
+    it "raises ArgumentError for an unsupported symbol operation" do
+      expect do
+        subject.override("rails", version: :explode)
+      end.to raise_error(ArgumentError, /unsupported override operation/)
+    end
+
+    it "rejects atomically when one field in a multi-field call is invalid" do
+      expect do
+        subject.override("rails", version: ">= 8.0", required_ruby_version: :ignore_upper)
+      end.to raise_error(ArgumentError, /unsupported override field/)
+      expect(subject.overrides).to eq([])
+    end
   end
 end