From 1977f3182171a1e04c5fd655da3f9b73186011a0 Mon Sep 17 00:00:00 2001
From: Juergen Hoeller <juergen.hoeller@broadcom.com>
Date: Tue, 20 Jan 2026 19:23:37 +0100
Subject: [PATCH] Prevent accidental printStackTrace() usage in main codebase

Closes gh-36185

(cherry picked from commit 65565de1a8968d605d2f1fac4754d76c792a8444)
---
 .../InvocationsRecorderClassTransformer.java  |  5 ++++-
 src/checkstyle/checkstyle-suppressions.xml    | 18 ++++++++-------
 src/checkstyle/checkstyle.xml                 | 22 ++++++++++---------
 3 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/spring-core-test/src/main/java/org/springframework/aot/agent/InvocationsRecorderClassTransformer.java b/spring-core-test/src/main/java/org/springframework/aot/agent/InvocationsRecorderClassTransformer.java
index 7d81935a697..9142d0e5225 100644
--- a/spring-core-test/src/main/java/org/springframework/aot/agent/InvocationsRecorderClassTransformer.java
+++ b/spring-core-test/src/main/java/org/springframework/aot/agent/InvocationsRecorderClassTransformer.java
@@ -43,6 +43,7 @@ class InvocationsRecorderClassTransformer implements ClassFileTransformer {
 
 	private final String[] ignoredPackages;
 
+
 	public InvocationsRecorderClassTransformer(String[] instrumentedPackages, String[] ignoredPackages) {
 		Assert.notNull(instrumentedPackages, "instrumentedPackages must not be null");
 		Assert.notNull(ignoredPackages, "ignoredPackages must not be null");
@@ -55,6 +56,7 @@ class InvocationsRecorderClassTransformer implements ClassFileTransformer {
 				.toArray(String[]::new);
 	}
 
+
 	@Override
 	public byte[] transform(@Nullable ClassLoader classLoader, String className, Class<?> classBeingRedefined,
 			ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
@@ -101,7 +103,7 @@ class InvocationsRecorderClassTransformer implements ClassFileTransformer {
 			fileReader.accept(classVisitor, 0);
 		}
 		catch (Exception ex) {
-			ex.printStackTrace();
+			System.err.println("Failed to transform class: " + ex);
 			return classfileBuffer;
 		}
 		if (classVisitor.isTransformed()) {
@@ -109,4 +111,5 @@ class InvocationsRecorderClassTransformer implements ClassFileTransformer {
 		}
 		return classfileBuffer;
 	}
+
 }
diff --git a/src/checkstyle/checkstyle-suppressions.xml b/src/checkstyle/checkstyle-suppressions.xml
index 129dad4d9bb..b9c5093af58 100644
--- a/src/checkstyle/checkstyle-suppressions.xml
+++ b/src/checkstyle/checkstyle-suppressions.xml
@@ -6,14 +6,15 @@
 	<suppress files="[\\/]build[\\/]generated[\\/]sources[\\/]" checks=".*"/>
 
 	<!-- Global: package-info.java -->
-	<suppress files="(^(?!.+[\\/]src[\\/]main[\\/]java[\\/]).*)|(.*framework-docs.*)" checks="JavadocPackage" />
-	<suppress files="(^(?!.+[\\/]src[\\/]main[\\/]java[\\/].*package-info\.java))|(.*framework-docs.*)|(.*spring-(context-indexer|instrument|jcl).*)" checks="RegexpSinglelineJava" id="packageLevelNonNullApiAnnotation" />
-	<suppress files="(^(?!.+[\\/]src[\\/]main[\\/]java[\\/].*package-info\.java))|(.*framework-docs.*)|(.*spring-(context-indexer|instrument|jcl).*)" checks="RegexpSinglelineJava" id="packageLevelNonNullFieldsAnnotation" />
+	<suppress files="(^(?!.+[\\/]src[\\/]main[\\/]java[\\/]).*)|(.*framework-docs.*)" checks="JavadocPackage"/>
+	<suppress files="(^(?!.+[\\/]src[\\/]main[\\/]java[\\/].*package-info\.java))|(.*framework-docs.*)|(.*spring-(context-indexer|instrument|jcl).*)" checks="RegexpSinglelineJava" id="packageLevelNonNullApiAnnotation"/>
+	<suppress files="(^(?!.+[\\/]src[\\/]main[\\/]java[\\/].*package-info\.java))|(.*framework-docs.*)|(.*spring-(context-indexer|instrument|jcl).*)" checks="RegexpSinglelineJava" id="packageLevelNonNullFieldsAnnotation"/>
 
 	<!-- Global: tests and test fixtures -->
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="AnnotationLocation|AnnotationUseStyle|AtclauseOrder|AvoidNestedBlocks|FinalClass|HideUtilityClassConstructor|InnerTypeLast|JavadocStyle|JavadocType|JavadocVariable|LeftCurly|MultipleVariableDeclarations|NeedBraces|OneTopLevelClass|OuterTypeFilename|RequireThis|SpringCatch|SpringJavadoc|SpringNoThis"/>
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="RegexpSinglelineJava" id="toLowerCaseWithoutLocale"/>
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="RegexpSinglelineJava" id="toUpperCaseWithoutLocale"/>
+	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="RegexpSinglelineJava" id="printStackTrace"/>
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="RegexpSinglelineJava" id="systemOutErrPrint"/>
 	<suppress files="[\\/]src[\\/](test|testFixtures)[\\/](java|java21)[\\/]" checks="SpringJUnit5" message="should not be public"/>
 	<suppress files="[\\/]src[\\/]test[\\/](java|java21)[\\/]org[\\/]springframework[\\/].+(Tests|Suite)" checks="IllegalImport" id="bannedJUnitJupiterImports"/>
@@ -23,7 +24,7 @@
 	<suppress files="[\\/]src[\\/]jmh[\\/]java[\\/]org[\\/]springframework[\\/]" checks="JavadocVariable|JavadocStyle|InnerTypeLast"/>
 
 	<!-- Framework docs -->
-	<suppress files="org[\\/]springframework[\\/]docs[\\/].+" checks="IllegalImport" id="bannedJUnitJupiterImports" />
+	<suppress files="org[\\/]springframework[\\/]docs[\\/].+" checks="IllegalImport" id="bannedJUnitJupiterImports"/>
 
 	<!-- spring-aop -->
 	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]aopalliance[\\/]" checks="IllegalImport" id="bannedImports" message="javax"/>
@@ -47,8 +48,8 @@
 	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/]aot[\\/]nativex[\\/]feature[\\/]" checks="RegexpSinglelineJava" id="systemOutErrPrint"/>
 	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/](core|util)[\\/](SpringProperties|SystemPropertyUtils)" checks="RegexpSinglelineJava" id="systemOutErrPrint"/>
 	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/]lang[\\/]" checks="IllegalImport" id="bannedImports" message="javax"/>
-	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/]lang[\\/]" checks="RegexpSinglelineJava" id="packageLevelNonNullApiAnnotation" />
-	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/]lang[\\/]" checks="RegexpSinglelineJava" id="packageLevelNonNullFieldsAnnotation" />
+	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/]lang[\\/]" checks="RegexpSinglelineJava" id="packageLevelNonNullApiAnnotation"/>
+	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/]lang[\\/]" checks="RegexpSinglelineJava" id="packageLevelNonNullFieldsAnnotation"/>
 	<suppress files="[\\/]src[\\/]main[\\/]java[\\/]org[\\/]springframework[\\/]core[\\/]annotation[\\/]" checks="IllegalImport" id="bannedImports" message="javax"/>
 	<suppress files="[\\/]src[\\/]test[\\/]java[\\/]org[\\/]springframework[\\/]core[\\/]annotation[\\/]" checks="IllegalImport" id="bannedImports" message="javax"/>
 	<suppress files="ByteArrayEncoder" checks="SpringLambda"/>
@@ -58,8 +59,9 @@
 	<suppress files="StringDecoderBenchmark" checks="RegexpSinglelineJava" id="separatorSymbolLocation"/>
 
 	<!-- spring-core-test -->
-	<suppress files="CompileWithForkedClassLoader" checks="IllegalImport" id="bannedJUnitJupiterImports" />
-	<suppress files="org[\\/]springframework[\\/]aot[\\/]test[\\/]agent[\\/].+" checks="IllegalImport" id="bannedJUnitJupiterImports" />
+	<suppress files="CompileWithForkedClassLoader" checks="IllegalImport" id="bannedJUnitJupiterImports"/>
+	<suppress files="org[\\/]springframework[\\/]aot[\\/]agent[\\/].+" checks="RegexpSinglelineJava" id="systemOutErrPrint"/>
+	<suppress files="org[\\/]springframework[\\/]aot[\\/]test[\\/]agent[\\/].+" checks="IllegalImport" id="bannedJUnitJupiterImports"/>
 
 	<!-- spring-expression -->
 	<suppress files="ExpressionException" checks="MutableException"/>
diff --git a/src/checkstyle/checkstyle.xml b/src/checkstyle/checkstyle.xml
index 315ddaea135..6df21bb629a 100644
--- a/src/checkstyle/checkstyle.xml
+++ b/src/checkstyle/checkstyle.xml
@@ -73,8 +73,7 @@
 		<module name="TypeName">
 			<property name="format" value="^[A-Z][a-zA-Z0-9_$]*(?&lt;!Test)$"/>
 			<property name="tokens" value="CLASS_DEF"/>
-			<message key="name.invalidPattern"
-				value="Class name ''{0}'' must not end with ''Test'' (checked pattern ''{1}'')."/>
+			<message key="name.invalidPattern" value="Class name ''{0}'' must not end with ''Test'' (checked pattern ''{1}'')."/>
 		</module>
 
 		<!-- Coding -->
@@ -135,8 +134,7 @@
 		<module name="com.puppycrawl.tools.checkstyle.checks.imports.IllegalImportCheck">
 			<property name="id" value="bannedJUnit4Imports"/>
 			<property name="regexp" value="true"/>
-			<property name="illegalClasses"
-				value="^org\.junit\.(Test|BeforeClass|AfterClass|Before|After|Ignore|FixMethodOrder|Rule|ClassRule|Assert|Assume)$,^org\.junit\.(Assert|Assume)\..+,^org\.junit\.(experimental|internal|matchers|rules|runner|runners|validator)\..+"/>
+			<property name="illegalClasses" value="^org\.junit\.(Test|BeforeClass|AfterClass|Before|After|Ignore|FixMethodOrder|Rule|ClassRule|Assert|Assume)$,^org\.junit\.(Assert|Assume)\..+,^org\.junit\.(experimental|internal|matchers|rules|runner|runners|validator)\..+"/>
 		</module>
 		<module name="com.puppycrawl.tools.checkstyle.checks.imports.IllegalImportCheck">
 			<property name="id" value="bannedJUnitJupiterImports"/>
@@ -254,21 +252,25 @@
 					  value="String.toUpperCase() should be String.toUpperCase(Locale.ROOT)"/>
 			<property name="ignoreComments" value="true"/>
 		</module>
+		<module name="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineJavaCheck">
+			<property name="id" value="printStackTrace"/>
+			<property name="format" value="\.printStackTrace\(\)"/>
+			<property name="maximum" value="0"/>
+			<property name="message" value="Printing a stacktrace to the console is forbidden in the main codebase"/>
+			<property name="ignoreComments" value="true"/>
+		</module>
 		<module name="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineJavaCheck">
 			<property name="id" value="systemOutErrPrint"/>
 			<property name="format" value="System\.(out|err)\.print"/>
 			<property name="maximum" value="0"/>
-			<property name="message"
-					  value="Printing to System.out and System.err is forbidden in the main codebase"/>
+			<property name="message" value="Printing to System.out and System.err is forbidden in the main codebase"/>
 			<property name="ignoreComments" value="true"/>
 		</module>
 		<module
 			name="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineJavaCheck">
 			<property name="maximum" value="0"/>
-			<property name="format"
-				value="assertThatExceptionOfType\((NullPointerException|IllegalArgumentException|IOException|IllegalStateException)\.class\)"/>
-			<property name="message"
-				value="Please use specialized AssertJ assertThat*Exception method."/>
+			<property name="format" value="assertThatExceptionOfType\((NullPointerException|IllegalArgumentException|IOException|IllegalStateException)\.class\)"/>
+			<property name="message" value="Please use specialized AssertJ assertThat*Exception method."/>
 			<property name="ignoreComments" value="true"/>
 		</module>
 		<module name="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineJavaCheck">