Fix building native python dependencies for pip-compile

python/helpers/requirements.txt

@@ -4,6 +4,7 @@ hashin==0.15.0
 pipenv==2018.11.26
 pipfile==0.0.2
 poetry==1.1.4
+wheel==0.36.0
 
 # Some dependencies will only install if Cython is present
 Cython==0.29.21

python/lib/dependabot/python/update_checker/pip_compile_version_resolver.rb

@@ -28,13 +28,15 @@ class PipCompileVersionResolver
           /git clone -q (?<url>[^\s]+).* /.freeze
         GIT_REFERENCE_NOT_FOUND_REGEX =
           /egg=(?<name>\S+).*.*WARNING: Did not find branch or tag \'(?<tag>[^\n"]+)\'/m.freeze
+        NATIVE_COMPILATION_ERROR = "pip._internal.exceptions.InstallationError: Command errored out with exit status 1"
 
         attr_reader :dependency, :dependency_files, :credentials
 
         def initialize(dependency:, dependency_files:, credentials:)
           @dependency               = dependency
           @dependency_files         = dependency_files
           @credentials              = credentials
+          @build_isolation = true
         end
 
         def latest_resolvable_version(requirement: nil)
@@ -90,10 +92,22 @@ def fetch_latest_resolvable_version_string(requirement:)
                 parse_updated_files
               end
             rescue SharedHelpers::HelperSubprocessFailed => e
+              retry_count ||= 0
+              retry_count += 1
+
+              if compilation_error?(e) && retry_count <= 1
+                @build_isolation = false
+                retry
+              end
+
               handle_pip_compile_errors(e)
             end
         end
 
+        def compilation_error?(error)
+          error.message.include?(NATIVE_COMPILATION_ERROR)
+        end
+
         # rubocop:disable Metrics/AbcSize
         def handle_pip_compile_errors(error)
           if error.message.include?("Could not find a version")
@@ -194,7 +208,7 @@ def run_command(command, env: python_env)
         end
 
         def pip_compile_options(filename)
-          options = ["--build-isolation"]
+          options = @build_isolation ? ["--build-isolation"] : ["--no-build-isolation"]
           options += pip_compile_index_options
 
           if (requirements_file = compiled_file_for_filename(filename))

python/spec/dependabot/python/update_checker/pip_compile_version_resolver_spec.rb

@@ -454,6 +454,16 @@
         end
       end
     end
+
+    context "with native dependencies that are not pre-built" do
+      let(:manifest_fixture_name) { "native_dependencies.in" }
+      let(:generated_fixture_name) { "pip_compile_native_dependencies.txt" }
+      let(:dependency_name) { "cryptography" }
+      let(:dependency_version) { "2.2.2" }
+      let(:updated_requirement) { "> 3.0.0" }
+
+      it { is_expected.to eq(Gem::Version.new("3.2.1")) }
+    end
   end
 
   describe "#resolvable?" do

python/spec/fixtures/pip_compile_files/native_dependencies.in

@@ -0,0 +1,3 @@
+numpy
+cryptography
+pandas

python/spec/fixtures/requirements/pip_compile_native_dependencies.txt

@@ -0,0 +1,16 @@
+#
+# This file is autogenerated by pip-compile
+# To update, run:
+#
+#    pip-compile --no-build-isolation
+#
+asn1crypto==1.4.0         # via cryptography
+cffi==1.11.5              # via cryptography
+cryptography==2.2.2       # via -r requirements.in
+idna==2.10                # via cryptography
+numpy==1.14.2             # via -r requirements.in, pandas
+pandas==0.22.0            # via -r requirements.in
+pycparser==2.18           # via cffi
+python-dateutil==2.8.1    # via pandas
+pytz==2020.4              # via pandas
+six==1.11.0               # via cryptography, python-dateutil