PY-80049: Check Python2 version correctly.

We execute `--version` to find python version.
Since 3.4 Python uses stdout for output, but before that it used stderr.

We now check both: stdout and stderr.

GitOrigin-RevId: ca9059b71cabbd1a94e26523192cdf9eeb8c1eb1

python/python-sdk/src/com/jetbrains/python/PythonBinaryExt.kt

@@ -4,6 +4,7 @@ import com.intellij.openapi.util.NlsSafe
 import com.intellij.platform.eel.getOr
 import com.intellij.platform.eel.path.EelPath
 import com.intellij.platform.eel.provider.getEelDescriptor
+import com.intellij.platform.eel.provider.utils.EelProcessExecutionResult
 import com.intellij.platform.eel.provider.utils.exec
 import com.intellij.platform.eel.provider.utils.stderrString
 import com.intellij.platform.eel.provider.utils.stdoutString
@@ -22,7 +23,6 @@ import kotlin.io.path.pathString
 import kotlin.time.Duration.Companion.seconds
 
 
-// TODO: PythonInterpreterService: validate system python
 /**
  * Ensures that this python is executable and returns its version. Error if python is broken.
  *
@@ -31,24 +31,25 @@ import kotlin.time.Duration.Companion.seconds
  */
 @ApiStatus.Internal
 suspend fun PythonBinary.validatePythonAndGetVersion(): Result<LanguageLevel, @NlsSafe String> = withContext(Dispatchers.IO) {
-  val smokeTestOutput = executeWithResult("-c", "print(1)").getOr { return@withContext it }.trim()
+  val smokeTestOutput = executeWithResult("-c", "print(1)").getOr { return@withContext it }.stdoutString.trim()
   if (smokeTestOutput != "1") {
     return@withContext failure(message("python.get.version.error", pathString, smokeTestOutput))
   }
 
-  val versionString = executeWithResult(PYTHON_VERSION_ARG).getOr { return@withContext it }
+  val versionOutput = executeWithResult(PYTHON_VERSION_ARG).getOr { return@withContext it }
+  // Python 2 might return version as stderr, see https://bugs.python.org/issue18338
+  val versionString = versionOutput.stdoutString.let { it.ifBlank { versionOutput.stderrString } }
   val languageLevel = getLanguageLevelFromVersionStringStaticSafe(versionString.trim())
   if (languageLevel == null) {
-    return@withContext failure(message("python.get.version.wrong.version", pathString, versionString))
+    return@withContext failure(message("python.get.version.wrong.version", pathString, versionOutput))
   }
   return@withContext Result.success(languageLevel)
 }
 
 /**
- * Executes [this] with [args], returns either stdout or error (if execution failed or exit code != 0)
+ * Executes [this] with [args], returns either output or error (if execution failed or exit code != 0)
  */
-@ApiStatus.Internal
-suspend fun PythonBinary.executeWithResult(vararg args: String): Result<@NlsSafe String, @NlsSafe String> {
+private suspend fun PythonBinary.executeWithResult(vararg args: String): Result<@NlsSafe EelProcessExecutionResult, @NlsSafe String> {
   val output = exec(*args, timeout = 5.seconds).getOr {
     val text = it.error?.message ?: message("python.get.version.too.long", pathString)
     return failure(text)
@@ -57,7 +58,7 @@ suspend fun PythonBinary.executeWithResult(vararg args: String): Result<@NlsSafe
     failure(message("python.get.version.error", pathString, "code ${output.exitCode}, ${output.stderrString}"))
   }
   else {
-    Result.success(output.stdoutString)
+    Result.success(output)
   }
 }
 

python/services/system-python/tests/com/intellij/python/junit5Tests/env/systemPython/Py27Test.kt

@@ -0,0 +1,19 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.python.junit5Tests.env.systemPython
+
+import com.intellij.python.community.services.systemPython.SystemPythonService
+import com.intellij.python.junit5Tests.framework.env.PyEnvTestCase
+import com.intellij.testFramework.common.timeoutRunBlocking
+import com.jetbrains.python.getOrThrow
+import com.jetbrains.python.psi.LanguageLevel
+import org.junit.jupiter.api.Test
+
+@PyEnvTestCase
+class Py27Test {
+  @Test
+  fun testPy27(): Unit = timeoutRunBlocking {
+    val testEnvironments = SystemPythonService().findSystemPythons()
+    val python27 = testEnvironments.firstOrNull { it.languageLevel == LanguageLevel.PYTHON27 } ?: error("No 2.7 found in $testEnvironments")
+    SystemPythonService().registerSystemPython(python27.pythonBinary).getOrThrow()
+  }
+}

python/services/system-python/tests/com/intellij/python/junit5Tests/env/systemPython/SystemPythonServiceShowCaseTest.kt

@@ -38,6 +38,7 @@ import org.junit.jupiter.api.io.TempDir
 import java.nio.file.Path
 import kotlin.io.path.deleteExisting
 import kotlin.io.path.pathString
+import kotlin.time.Duration.Companion.minutes
 
 @PyEnvTestCase
 class SystemPythonServiceShowCaseTest {
@@ -49,7 +50,7 @@ class SystemPythonServiceShowCaseTest {
       val eelApi = systemPython.pythonBinary.getEelDescriptor().upgrade()
       val process = eelApi.exec.executeProcess(systemPython.pythonBinary.pathString, "--version").getOrThrow()
       val output = async {
-        process.stdout.readWholeText().getOrThrow()
+        (if (systemPython.languageLevel.isPy3K) process.stdout else process.stderr).readWholeText().getOrThrow()
       }
       Assertions.assertEquals(0, process.exitCode.await(), "Wrong exit code")
       val versionString = PythonSdkFlavor.getLanguageLevelFromVersionStringStaticSafe(output.await())!!

python/services/system-python/tests/com/intellij/python/junit5Tests/env/systemPython/impl/EnvTestPythonProvider.kt

@@ -6,9 +6,11 @@ import com.intellij.openapi.util.Disposer
 import com.intellij.platform.eel.EelApi
 import com.intellij.platform.eel.provider.localEel
 import com.intellij.python.community.services.systemPython.SystemPythonProvider
+import com.intellij.python.community.testFramework.testEnv.TypeVanillaPython
 import com.intellij.python.community.testFramework.testEnv.TypeVanillaPython3
 import com.jetbrains.python.PythonBinary
 import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.merge
 import kotlinx.coroutines.flow.toSet
 
 /**
@@ -18,8 +20,8 @@ internal class EnvTestPythonProvider : SystemPythonProvider {
   override suspend fun findSystemPythons(eelApi: EelApi): Result<Set<PythonBinary>> {
     var pythons = emptySet<PythonBinary>()
     if (eelApi == localEel) {
-      pythons = TypeVanillaPython3
-        .getTestEnvironments()
+      // Add Py27 temporary to test Py27
+      pythons = merge(TypeVanillaPython3.getTestEnvironments(), TypeVanillaPython2.getTestEnvironments())
         .map { (python, closeable) ->
           Disposer.register(ApplicationManager.getApplication()) {
             closeable.close()
@@ -31,4 +33,6 @@ internal class EnvTestPythonProvider : SystemPythonProvider {
 
     return Result.success(pythons)
   }
-}
+}
+
+private object TypeVanillaPython2 : TypeVanillaPython("python2.7")

python/setup-test-environment/src/com/intellij/python/community/testFramework/testEnv/PythonType.kt

@@ -41,7 +41,6 @@ abstract class PythonType<T : Any>(private val tag: @NonNls String) {
           ?: error("Can't get language level for $flavor , $binary")
         }
         .sortedByDescending { (_, languageLevel) -> languageLevel }
-        .filter { (_, languageLevel) -> languageLevel.isPy3K }
         .map { (path, _) -> path }
     }
     return pythons.asFlow()

python/setup-test-environment/src/com/intellij/python/community/testFramework/testEnv/TypeVanillaPython3.kt

@@ -11,7 +11,7 @@ import com.jetbrains.python.PyNames
 import com.jetbrains.python.PythonBinary
 import java.nio.file.Path
 
-data object TypeVanillaPython3 : PythonType<PythonBinary>("python3") {
+open class TypeVanillaPython(tag: String) : PythonType<PythonBinary>(tag) {
   override suspend fun createSdkFor(python: PythonBinary): Sdk = createSdk(python)
 
   fun createSdk(python: PythonBinary): Sdk =
@@ -27,4 +27,6 @@ data object TypeVanillaPython3 : PythonType<PythonBinary>("python3") {
       Disposer.dispose(disposable)
     })
   }
-}
+}
+
+object TypeVanillaPython3 : TypeVanillaPython("python3")