[python] PY-85601 Add "invalid escape sequence" inspection

GitOrigin-RevId: d750f06efc5e42678073de084ecb2976acedd4b9
2026-09-27 10:03:11 +07:00 · 2025-12-02 21:55:58 +00:00
parent 3e223423f2
commit 788e8300e4
15 changed files with 285 additions and 0 deletions
@@ -0,0 +1,22 @@
+<html>
+<body>
+Reports invalid escape sequences in string and bytes literals.
+
+<p>
+  Starting from Python 3.6, escape sequences that are not recognized (such as <code>\.</code>) produce a <code>SyntaxWarning</code>.
+  In future Python versions, they will become a <code>SyntaxError</code>.
+</p>
+<p>
+  To fix this, you can either escape the backslash (e.g., <code>\\.</code>) or use a raw string (e.g., <code>r'\.'</code>).
+</p>
+<p><b>Example:</b></p>
+<pre><code>
+# Warning: Invalid escape sequence '\.'
+print('\.')
+
+# Correct
+print(r'\.')
+print('\\.')
+</code></pre>
+</body>
+</html>
@@ -269,6 +269,7 @@
    <localInspection language="Python" shortName="PyAssertTypeInspection" suppressId="PyAssertType" bundle="messages.PyPsiBundle" key="INSP.NAME.assert.type" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WARNING" implementationClass="com.jetbrains.python.inspections.PyAssertTypeInspection"/>
    <localInspection language="Python" shortName="PyEnumInspection" suppressId="PyEnum" bundle="messages.PyPsiBundle" key="INSP.NAME.enum" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WARNING" implementationClass="com.jetbrains.python.inspections.PyEnumInspection"/>
    <localInspection language="Python" shortName="PyNewTypeInspection" suppressId="PyNewType" bundle="messages.PyPsiBundle" key="INSP.NAME.new.type" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WARNING" implementationClass="com.jetbrains.python.inspections.PyNewTypeInspection"/>
+    <localInspection language="Python" shortName="PyInvalidEscapeSequenceInspection" suppressId="PyInvalidEscapeSequence" bundle="messages.PyPsiBundle" key="INSP.NAME.invalid.escape.sequence" groupKey="INSP.GROUP.python" enabledByDefault="true" level="WARNING" implementationClass="com.jetbrains.python.inspections.PyInvalidEscapeSequenceInspection"/>

    <intentionAction>
      <language>Python</language>
@@ -1378,3 +1378,11 @@ QFIX.remove.cast.call=Remove 'cast' call
 QFIX.add.source.root.notification.text=''{0}'' has been marked as source root
 QFIX.add.source.root.notification.ok=Ok
 QFIX.add.source.root.notification.revert=Revert
+
+# PyInvalidEscapeSequenceInspection
+INSP.NAME.invalid.escape.sequence=Invalid escape sequence
+INSP.invalid.escape.sequence=Invalid escape sequence ''{0}''
+
+# Quick fixes for PyInvalidEscapeSequenceInspection
+QFIX.escape.backslash=Escape backslash
+QFIX.convert.to.raw.string=Convert to raw string
@@ -0,0 +1,91 @@
+package com.jetbrains.python.inspections
+
+import com.intellij.codeInspection.LocalInspectionToolSession
+import com.intellij.codeInspection.LocalQuickFix
+import com.intellij.codeInspection.ProblemHighlightType
+import com.intellij.codeInspection.ProblemsHolder
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiElementVisitor
+import com.jetbrains.python.PyPsiBundle
+import com.jetbrains.python.inspections.quickfix.PyConvertToRawStringQuickFix
+import com.jetbrains.python.inspections.quickfix.PyEscapeBackslashQuickFix
+import com.jetbrains.python.psi.PyFormattedStringElement
+import com.jetbrains.python.psi.PyStringElement
+import com.jetbrains.python.psi.PyStringLiteralExpression
+import com.jetbrains.python.psi.impl.PyStringLiteralDecoder
+import com.jetbrains.python.psi.types.TypeEvalContext
+
+class PyInvalidEscapeSequenceInspection : PyInspection() {
+
+  override fun buildVisitor(
+    holder: ProblemsHolder,
+    isOnTheFly: Boolean,
+    session: LocalInspectionToolSession,
+  ): PsiElementVisitor = Visitor(holder, PyInspectionVisitor.getContext(session))
+
+  private class Visitor(holder: ProblemsHolder?, context: TypeEvalContext) : PyInspectionVisitor(holder, context) {
+
+    override fun visitPyStringLiteralExpression(node: PyStringLiteralExpression) =
+      node.stringElements.forEach { processString(it, node) }
+
+    private fun processString(element: PyStringElement, node: PyStringLiteralExpression) {
+      if (element.prefix.contains("r", ignoreCase = true)) return
+
+      val content = element.contentRange.substring(element.text)
+      val offsetInNode = element.textRange.startOffset + element.contentRange.startOffset - node.textRange.startOffset
+
+      val fstringRanges = if (element is PyFormattedStringElement) {
+        element.literalPartRanges.asSequence().map { it.shiftLeft(element.contentRange.startOffset) }
+      }
+      else {
+        sequenceOf(TextRange(0, content.length))
+      }
+
+      val validEscapes = fstringRanges.flatMap { range ->
+        PyStringLiteralDecoder.PATTERN_ESCAPE.toRegex()
+          .findAll(content, range.startOffset)
+          .takeWhile { it.range.last < range.endOffset }
+          .map { it.range }
+      }
+        .iterator()
+      val hasValidEscapes = validEscapes.hasNext()
+      var curValidEscape = if (hasValidEscapes) validEscapes.next() else null
+
+      for (range in fstringRanges) {
+        var charIndex = range.startOffset
+        while (charIndex < range.endOffset - 1) {
+
+          if (content[charIndex] != '\\') {
+            charIndex++
+            continue
+          }
+
+          while (curValidEscape?.let { it.last < charIndex } == true) {
+            curValidEscape = if (validEscapes.hasNext()) validEscapes.next() else null
+          }
+          if (curValidEscape?.contains(charIndex) == true) {
+            charIndex = curValidEscape.last + 1
+            continue
+          }
+
+          val problemOffset = offsetInNode + charIndex
+
+          val fixes = LocalQuickFix.notNullElements(
+            PyEscapeBackslashQuickFix(problemOffset),
+            if (!hasValidEscapes) PyConvertToRawStringQuickFix(problemOffset) else null
+          )
+
+          registerProblem(
+            node,
+            PyPsiBundle.message("INSP.invalid.escape.sequence", "\\${content[charIndex + 1]}"),
+            ProblemHighlightType.GENERIC_ERROR_OR_WARNING,
+            null,
+            TextRange(problemOffset, problemOffset + 2),
+            *fixes
+          )
+          charIndex += 2
+        }
+      }
+    }
+  }
+}
@@ -0,0 +1,28 @@
+package com.jetbrains.python.inspections.quickfix
+
+import com.intellij.codeInsight.intention.LowPriorityAction
+import com.intellij.modcommand.ModPsiUpdater
+import com.intellij.modcommand.PsiUpdateModCommandQuickFix
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
+import com.jetbrains.python.PyPsiBundle
+import com.jetbrains.python.psi.PyElementGenerator
+import com.jetbrains.python.psi.PyStringLiteralExpression
+
+class PyConvertToRawStringQuickFix(private val offsetInElement: Int) : PsiUpdateModCommandQuickFix(), LowPriorityAction {
+  override fun getFamilyName(): String = PyPsiBundle.message("QFIX.convert.to.raw.string")
+
+  override fun applyFix(project: Project, element: PsiElement, updater: ModPsiUpdater) {
+    if (element !is PyStringLiteralExpression) return
+
+    val part = element.stringElements.find { it.textRangeInParent.contains(offsetInElement) } ?: return
+    if (part.prefix.contains("r", ignoreCase = true)) return
+
+    val newText = "r" + part.text
+
+    val newPart = PyElementGenerator.getInstance(project)
+                    .createStringLiteralAlreadyEscaped(newText)
+                    .stringElements.firstOrNull() ?: return
+    part.replace(newPart)
+  }
+}
@@ -0,0 +1,25 @@
+package com.jetbrains.python.inspections.quickfix
+
+import com.intellij.modcommand.ModPsiUpdater
+import com.intellij.modcommand.PsiUpdateModCommandQuickFix
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
+import com.jetbrains.python.PyPsiBundle
+import com.jetbrains.python.psi.PyElementGenerator
+import com.jetbrains.python.psi.PyStringLiteralExpression
+
+class PyEscapeBackslashQuickFix(private val offsetInElement: Int) : PsiUpdateModCommandQuickFix() {
+  override fun getFamilyName(): String = PyPsiBundle.message("QFIX.escape.backslash")
+
+  override fun applyFix(project: Project, element: PsiElement, updater: ModPsiUpdater) {
+    if (element !is PyStringLiteralExpression) return
+
+    if (offsetInElement >= element.textLength || element.text[offsetInElement] != '\\') return
+
+    val newText = StringBuilder(element.text).insert(offsetInElement, "\\").toString()
+
+    val newElement = PyElementGenerator.getInstance(project)
+      .createStringLiteralAlreadyEscaped(newText)
+    element.replace(newElement)
+  }
+}
@@ -0,0 +1,9 @@
+s1 = "<warning descr="Invalid escape sequence '\.'">\.</warning>"
+
+s2 = "<warning descr="Invalid escape sequence '\z'">\z</warning>"
+
+s3 = "\a \b \f \n \r \t \v \\ \' \" \0 \x41 \u1234 \U00012345 \N{SNOWMAN}"
+
+s4 = r"\."
+
+s5 = "  <warning descr="Invalid escape sequence '\.'">\.</warning>  <warning descr="Invalid escape sequence '\z'">\z</warning>  "
@@ -0,0 +1,9 @@
+b1 = b"<warning descr="Invalid escape sequence '\.'">\.</warning>"
+
+b2 = b"<warning descr="Invalid escape sequence '\z'">\z</warning>"
+
+b3 = b"\a \b \f \n \r \t \v \\ \' \" \0 \x41 \u1234 \U00012345 \N{SNOWMAN}"
+
+b4 = rb"\."
+
+b5 = b"  <warning descr="Invalid escape sequence '\.'">\.</warning>  <warning descr="Invalid escape sequence '\z'">\z</warning>  "
@@ -0,0 +1 @@
+s = "postfix" '\n<caret>\.' "suffix"
@@ -0,0 +1 @@
+s = "prefix" r'\.' "suffix"
@@ -0,0 +1 @@
+s = "prefix" '<caret>\.' "suffix"
@@ -0,0 +1 @@
+s = "prefix" '\\.' "suffix"
@@ -0,0 +1 @@
+s = "prefix" '<caret>\.' "suffix"
@@ -0,0 +1,44 @@
+f1 = f"<warning descr="Invalid escape sequence '\.'">\.</warning>"
+
+f2 = f"\a \b \f \n \r \t \v \\ \' \" \0 \x41 \u1234 \U00012345 \N{SNOWMAN}"
+
+f3 = f"foo {1} <warning descr="Invalid escape sequence '\ '">\ </warning>"
+
+f4 = f"foo { f'<warning descr="Invalid escape sequence '\.'">\.</warning>' }"
+
+f5 = f"level1 { f'level2 { f"level3 <warning descr="Invalid escape sequence '\.'">\.</warning>" }' } <warning descr="Invalid escape sequence '\.'">\.</warning>"
+
+f6 = f"valid \n invalid <warning descr="Invalid escape sequence '\.'">\.</warning> valid \t"
+
+f7 = f"{{ <warning descr="Invalid escape sequence '\.'">\.</warning> }}"
+
+f8 = f"<warning descr="Invalid escape sequence '\{'">\{</warning>{"
+
+f9 = f"""
+  <warning descr="Invalid escape sequence '\.'">\.</warning>
+  {1}
+  valid \n
+  <warning descr="Invalid escape sequence '\z'">\z</warning>
+"""
+
+f10 = f"text <warning descr="Invalid escape sequence '\.'">\.</warning> { '\n' } text"
+
+f11 = f"list {[1, 2]} set { {1, 2} } dict { {'k': 'v'} } <warning descr="Invalid escape sequence '\.'">\.</warning>"
+
+# \n and \x are escape sequences, while \z is not:
+f12 = f"expression { 1 + \
+n } <warning descr="Invalid escape sequence '\.'">\.</warning>"
+
+f13 = f"nested { f'inner { 1 + \
+x }' } "
+
+f16 = f"expression { 1 + \
+z } <warning descr="Invalid escape sequence '\.'">\.</warning>"
+
+f14 = f" { '\n' } { '<warning descr="Invalid escape sequence '\.'">\.</warning>' } "
+
+f15 = f" { {'key': '\n', 'val': '<warning descr="Invalid escape sequence '\.'">\.</warning>'} } "
+
+rf1 = rf"\."
+rf2 = rf"foo {1} \."
+rf3 = fr"foo {1} \."
@@ -0,0 +1,43 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.jetbrains.python.inspections
+
+import com.jetbrains.python.PyPsiBundle
+import com.jetbrains.python.fixtures.PyInspectionTestCase
+
+class PyInvalidEscapeSequenceInspectionTest : PyInspectionTestCase() {
+
+  override fun getInspectionClass(): Class<out PyInspection> = PyInvalidEscapeSequenceInspection::class.java
+
+  fun testBasic() = doTest()
+
+  fun testBytes() = doTest()
+
+  fun testFstrings() = doTest()
+
+  fun testEscapeBackslash() {
+    doQuickFixTest(PyPsiBundle.message("QFIX.escape.backslash"), "escapeBackslash_before.py", "escapeBackslash_after.py")
+  }
+
+  fun testConvertToRawString() {
+    doQuickFixTest(PyPsiBundle.message("QFIX.convert.to.raw.string"), "convertToRawString_before.py", "convertToRawString_after.py")
+  }
+
+  fun testConvertToRawStringNotAvailable() {
+    myFixture.configureByFile(testCaseDirectory + "convertToRawStringNotAvailable_before.py")
+    myFixture.enableInspections(getInspectionClass())
+
+    val actions = myFixture.filterAvailableIntentions(PyPsiBundle.message("QFIX.convert.to.raw.string"))
+    assertEmpty("Convert to raw string should not be available if string contains valid escapes", actions)
+
+    assertNotNull(myFixture.findSingleIntention(PyPsiBundle.message("QFIX.escape.backslash")))
+  }
+
+  private fun doQuickFixTest(hint: String, sourceFile: String, expectedFile: String) {
+    myFixture.configureByFile(testCaseDirectory + sourceFile)
+    myFixture.enableInspections(getInspectionClass())
+
+    val action = myFixture.findSingleIntention(hint)
+    myFixture.launchAction(action)
+    myFixture.checkResultByFile(testCaseDirectory + expectedFile)
+  }
+}