^ or \A anchors not at the beginning of the pattern and
+$, \Z or \z anchors not at the end of the pattern.
+In the wrong position these RegExp anchors prevent the pattern from matching anything.
+In case of the ^ and $ anchors, most likely the literal character was meant and the escape forgotten.
+
+
+New in 2018.1
+
+
\ No newline at end of file
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/inspection/UnexpectedAnchorInspection.java b/RegExpSupport/src/org/intellij/lang/regexp/inspection/UnexpectedAnchorInspection.java
new file mode 100644
index 000000000000..bd769875fdb5
--- /dev/null
+++ b/RegExpSupport/src/org/intellij/lang/regexp/inspection/UnexpectedAnchorInspection.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+ */
+package org.intellij.lang.regexp.inspection;
+
+import com.intellij.codeInspection.LocalInspectionTool;
+import com.intellij.codeInspection.ProblemsHolder;
+import com.intellij.psi.PsiComment;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.PsiWhiteSpace;
+import com.intellij.psi.util.PsiTreeUtil;
+import org.intellij.lang.regexp.psi.*;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class UnexpectedAnchorInspection extends LocalInspectionTool {
+
+ @Nls
+ @NotNull
+ @Override
+ public String getDisplayName() {
+ return "Begin or end anchor in unexpected position";
+ }
+
+ @NotNull
+ @Override
+ public PsiElementVisitor buildVisitor(@NotNull ProblemsHolder holder, boolean isOnTheFly) {
+ return new UnexpectedAnchorVisitor(holder);
+ }
+
+ private static class UnexpectedAnchorVisitor extends RegExpElementVisitor {
+
+ private final ProblemsHolder myHolder;
+
+ public UnexpectedAnchorVisitor(ProblemsHolder holder) {
+ myHolder = holder;
+ }
+
+ @Override
+ public void visitRegExpBoundary(RegExpBoundary boundary) {
+ super.visitRegExpBoundary(boundary);
+ final RegExpBoundary.Type type = boundary.getType();
+ switch (type) {
+ case BEGIN: // \A
+ if (!hasUnexpectedSibling(boundary, false, false)) return;
+ break;
+ case LINE_START: // ^
+ if (!hasUnexpectedSibling(boundary, false, true)) return;
+ break;
+ case END: // \z
+ case END_NO_LINE_TERM: // \Z
+ if (!hasUnexpectedSibling(boundary, true, false)) return;
+ break;
+ case LINE_END: // $
+ if (!hasUnexpectedSibling(boundary, true, true)) return;
+ break;
+ default:
+ return;
+ }
+ myHolder.registerProblem(boundary, "Anchor #ref in unexpected position");
+ }
+
+ private static boolean hasUnexpectedSibling(PsiElement element, boolean next, boolean line) {
+ PsiElement sibling = next
+ ? PsiTreeUtil.skipSiblingsForward(element, PsiComment.class, PsiWhiteSpace.class, RegExpSetOptions.class)
+ : PsiTreeUtil.skipSiblingsBackward(element, PsiComment.class, PsiWhiteSpace.class, RegExpSetOptions.class);
+ if (sibling == null) {
+ return false;
+ }
+ if (line) {
+ if (sibling instanceof RegExpChar) {
+ final int value = ((RegExpChar)sibling).getValue();
+ return value != '\n' && value != '\r';
+ }
+ else if (sibling instanceof RegExpSimpleClass) {
+ final RegExpSimpleClass.Kind kind = ((RegExpSimpleClass)sibling).getKind();
+ switch (kind) {
+ case ANY:
+ case NON_DIGIT:
+ case NON_WORD:
+ case SPACE:
+ case NON_HORIZONTAL_SPACE:
+ case NON_VERTICAL_SPACE:
+ case NON_XML_NAME_START:
+ case NON_XML_NAME_PART:
+ case UNICODE_LINEBREAK:
+ return false;
+ default:
+ return true;
+ }
+ }
+ return sibling instanceof RegExpBoundary;
+ }
+ return true;
+ }
+ }
+}
diff --git a/RegExpSupport/test/org/intellij/lang/regexp/inspection/UnexpectedAnchorInspectionTest.java b/RegExpSupport/test/org/intellij/lang/regexp/inspection/UnexpectedAnchorInspectionTest.java
new file mode 100644
index 000000000000..c25d878f0ea5
--- /dev/null
+++ b/RegExpSupport/test/org/intellij/lang/regexp/inspection/UnexpectedAnchorInspectionTest.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+ */
+package org.intellij.lang.regexp.inspection;
+
+import com.intellij.codeInspection.LocalInspectionTool;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Bas Leijdekkers
+ */
+@SuppressWarnings("RegExpUnexpectedAnchor")
+public class UnexpectedAnchorInspectionTest extends RegExpInspectionTestCase {
+
+ public void testSimple() {
+ highlightTest("