Merge branch '7.0.x' into update-UseDiamondOperator

.github/ISSUE_TEMPLATE/0rule_violation_false-positive.md

@@ -1,8 +1,8 @@
 ---
-name: Rule violation
-about: Let us know about a false positive/false negative
+name: Rule violation (false-positive)
+about: Let us know about a false-positive (a violation is reported on code that is not problematic)
 title: ''
-labels: 'a:false-positive, a:false-negative'
+labels: 'a:false-positive'
 assignees: ''
 
 ---
@@ -25,8 +25,6 @@ Please provide the rule name and a link to the rule documentation:
 
 **Expected outcome:**
 
-*   Does PMD report a violation, where there shouldn't be one? -> false-positive
-*   Is PMD missing to report a violation, where there should be one? -> false-negative
-
+PMD reports a violation at line ..., but that's wrong. That's a false positive.
 
 **Running PMD through:** *[CLI | Ant | Maven | Gradle | Designer | Other]*

.github/ISSUE_TEMPLATE/1rule_violation_false-negative.md

@@ -0,0 +1,30 @@
+---
+name: Rule violation (false-negative)
+about: Let us know about a false-negative (no violation is reported on problematic code)
+title: ''
+labels: 'a:false-negative'
+assignees: ''
+
+---
+<!-- Please, prefix the report title with the language it applies to within brackets, such as [java] or [apex] -->
+
+**Affects PMD Version:** 
+
+**Rule:**
+
+Please provide the rule name and a link to the rule documentation:
+<https://pmd.github.io/latest/pmd_rules_XXX_XXX.html#XXX>
+
+**Description:**
+
+**Code Sample demonstrating the issue:**
+
+```
+
+```
+
+**Expected outcome:**
+
+PMD should report a violation at line ..., but doesn't. This is a false-negative.
+
+**Running PMD through:** *[CLI | Ant | Maven | Gradle | Designer | Other]*

docs/_layouts/page.html

@@ -23,8 +23,9 @@ layout: default
         {% if page.editmepath %}
             {% assign editmepath = page.editmepath %}
         {% endif %}
-
-    <a target="_blank" href="https://github.com/{{site.github_editme_path}}{{editmepath}}" class="btn btn-outline-secondary githubEditButton" role="button"><i class="fab fa-github fa-lg"></i> Edit me</a>
+        {% unless page.editmepath == false %}
+        <a target="_blank" href="https://github.com/{{site.github_editme_path}}{{editmepath}}" class="btn btn-outline-secondary githubEditButton" role="button"><i class="fab fa-github fa-lg"></i> Edit me</a>
+        {% endunless %}
 
     {% endif %}
 

docs/pages/7_0_0_release_notes.md

@@ -157,6 +157,7 @@ The following previously deprecated rules have been finally removed:
     * [#3195](https://github.com/pmd/pmd/pull/3195): \[java] Improve rule UnnecessaryReturn to detect more cases
     * [#3218](https://github.com/pmd/pmd/pull/3218): \[java] Generalize UnnecessaryCast to flag all unnecessary casts
     * [#3221](https://github.com/pmd/pmd/issues/3221): \[java] PrematureDeclaration false positive for unused variables
+    * [#3238](https://github.com/pmd/pmd/issues/3238): \[java] Improve ExprContext, fix FNs of UnnecessaryCast
 * java-errorprone
     * [#1005](https://github.com/pmd/pmd/issues/1005): \[java] CloneMethodMustImplementCloneable triggers for interfaces
     * [#2532](https://github.com/pmd/pmd/issues/2532): \[java] AvoidDecimalLiteralsInBigDecimalConstructor can not detect the case new BigDecimal(Expression)

docs/pages/release_notes.md

@@ -21,6 +21,9 @@ This is a {{ site.pmd.release_type }} release.
 
 ### Fixed Issues
 
+*   doc
+    *   [#3230](https://github.com/pmd/pmd/issues/3230): \[doc] Remove "Edit me" button for language index pages
+
 ### API Changes
 
 ### External Contributions

pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleDocGenerator.java

@@ -182,6 +182,7 @@ public class RuleDocGenerator {
             lines.add("language_name: " + entry.getKey().getName());
             lines.add("permalink: " + LANGUAGE_INDEX_PERMALINK_PATTERN.replace("${language.tersename}", languageTersename));
             lines.add("folder: pmd/rules");
+            lines.add("editmepath: false");
             lines.add("---");
             lines.add(GENERATED_WARNING_NO_SOURCE);
 

pmd-doc/src/test/resources/expected/java.md

@@ -5,6 +5,7 @@ summary: Index of all built-in rules available for Java
 language_name: Java
 permalink: pmd_rules_java.html
 folder: pmd/rules
+editmepath: false
 ---
 <!-- DO NOT EDIT THIS FILE. This file is generated. -->
 ## Sample

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/ast/ExprContext.java

@@ -9,10 +9,13 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 
 import net.sourceforge.pmd.annotation.Experimental;
 import net.sourceforge.pmd.internal.util.AssertionUtil;
+import net.sourceforge.pmd.lang.java.types.JClassType;
 import net.sourceforge.pmd.internal.util.AssertionUtil;
 import net.sourceforge.pmd.lang.java.types.JTypeMirror;
 import net.sourceforge.pmd.lang.java.types.OverloadSelectionResult;
 import net.sourceforge.pmd.lang.java.types.TypeConversion;
+import net.sourceforge.pmd.lang.java.types.TypeSystem;
+import net.sourceforge.pmd.lang.java.types.TypesFromReflection;
 
 /**
  * Context of an expression. This determines the target type of poly
@@ -87,6 +90,10 @@ public abstract class ExprContext {
         return kind == CtxKind.Numeric;
     }
 
+    public boolean isString() {
+        return kind == CtxKind.String;
+    }
+
     boolean canGiveContextToPoly(boolean lambda) {
         return true;
     }
@@ -103,8 +110,14 @@ public abstract class ExprContext {
         return new RegularCtx(targetType, CtxKind.OtherNonPoly);
     }
 
+    static ExprContext newStringCtx(TypeSystem ts) {
+        JClassType stringType = (JClassType) TypesFromReflection.fromReflect(String.class, ts);
+        return new RegularCtx(stringType, CtxKind.String);
+    }
+
     static ExprContext newNumericContext(JTypeMirror targetType) {
         if (targetType.isPrimitive()) {
+            assert targetType.isNumeric() : targetType;
             return new RegularCtx(targetType, CtxKind.Numeric);
         }
         return RegularCtx.NO_CTX; // error
@@ -152,6 +165,11 @@ public abstract class ExprContext {
         public boolean isInvocationContext() {
             return true;
         }
+
+        @Override
+        public String toString() {
+            return "InvocCtx{arg=" + arg + ", node=" + node + '}';
+        }
     }
 
     /**
@@ -198,8 +216,13 @@ public abstract class ExprContext {
          */
         Numeric,
 
-        // todo similarly, string contexts allow a string conversion, which uses
-        //  String::valueOf.
+        /**
+         * String contexts, which convert the operand to a string using {@link String#valueOf(Object)},
+         * or the equivalent for a primitive type. They accept operands of any type.
+         * This is the context for the operands of a string concatenation expression,
+         * and for the message of an assert statement.
+         */
+        String,
 
         /** Kind for a standalone ternary (both branches are then in this context). */
         Ternary,
@@ -212,10 +235,7 @@ public abstract class ExprContext {
          * but not for poly expressions. These do not flow through ternary branches.
          * These include:
          * <ul>
-         * <li>TODO String contexts, which convert the operand to a string using {@link String#valueOf(Object)},
-         * or the equivalent for a primitive type. They accept operands of any type.
-         * This is the context for the operands of a string concatenation expression,
-         * and for the message of an assert statement.
+         * <li>
          * <li>Boolean contexts, which unbox their operand to a boolean.
          * They accept operands of type boolean or Boolean. This is the
          * context for e.g. the condition of an {@code if} statement, an
@@ -261,5 +281,10 @@ public abstract class ExprContext {
         public @Nullable JTypeMirror getTargetType() {
             return targetType;
         }
+
+        @Override
+        public String toString() {
+            return "RegularCtx{kind=" + kind + ", targetType=" + targetType + '}';
+        }
     }
 }

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/ast/PolyResolution.java

@@ -22,14 +22,13 @@ import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.java.ast.ExprContext.InvocCtx;
 import net.sourceforge.pmd.lang.java.ast.ExprContext.RegularCtx;
 import net.sourceforge.pmd.lang.java.rule.internal.JavaRuleUtil;
-import net.sourceforge.pmd.lang.java.types.JClassType;
 import net.sourceforge.pmd.lang.java.types.JMethodSig;
 import net.sourceforge.pmd.lang.java.types.JPrimitiveType;
 import net.sourceforge.pmd.lang.java.types.JTypeMirror;
 import net.sourceforge.pmd.lang.java.types.OverloadSelectionResult;
 import net.sourceforge.pmd.lang.java.types.TypeOps;
 import net.sourceforge.pmd.lang.java.types.TypeSystem;
-import net.sourceforge.pmd.lang.java.types.TypesFromReflection;
+import net.sourceforge.pmd.lang.java.types.TypeTestUtil;
 import net.sourceforge.pmd.lang.java.types.internal.infer.ExprMirror.BranchingMirror;
 import net.sourceforge.pmd.lang.java.types.internal.infer.ExprMirror.FunctionalExprMirror;
 import net.sourceforge.pmd.lang.java.types.internal.infer.ExprMirror.InvocationMirror;
@@ -54,10 +53,10 @@ final class PolyResolution {
         this.infer = infer;
         this.ts = infer.getTypeSystem();
         this.exprMirrors = JavaExprMirrors.forTypeResolution(infer);
-        JClassType stringType = (JClassType) TypesFromReflection.fromReflect(String.class, ts);
-        booleanCtx = ExprContext.newNonPolyContext(ts.BOOLEAN);
-        stringCtx = ExprContext.newNonPolyContext(stringType);
-        intCtx = ExprContext.newNumericContext(ts.INT);
+
+        this.stringCtx = ExprContext.newStringCtx(ts);
+        this.booleanCtx = ExprContext.newNonPolyContext(ts.BOOLEAN);
+        this.intCtx = ExprContext.newNumericContext(ts.INT);
     }
 
     private boolean isPreJava8() {
@@ -94,9 +93,11 @@ final class PolyResolution {
             if (isPreJava8()) {
                 // safe cast because ASTSwitchExpression doesn't exist pre java 13
                 ASTConditionalExpression conditional = (ASTConditionalExpression) e;
-                return computeStandaloneConditionalType(this.ts,
-                                                        conditional.getThenBranch().getTypeMirror(),
-                                                        conditional.getElseBranch().getTypeMirror());
+                return computeStandaloneConditionalType(
+                    this.ts,
+                    conditional.getThenBranch().getTypeMirror(),
+                    conditional.getElseBranch().getTypeMirror()
+                );
             }
 
             // Note that this creates expr mirrors for all subexpressions,
@@ -482,14 +483,20 @@ final class PolyResolution {
 
             return booleanCtx; // condition
 
-        } else if (papa instanceof ASTConditionalExpression && node.getIndexInParent() != 0) {
-            if (isPreJava8()) {
-                return RegularCtx.NO_CTX;
-            }
-            assert ((ASTConditionalExpression) papa).isStandalone()
-                : "Expected standalone ternary, otherwise doesCascadeContext(..) would have returned true";
+        } else if (papa instanceof ASTConditionalExpression) {
 
-            return ExprContext.newStandaloneTernaryCtx(((ASTConditionalExpression) papa).getTypeMirror());
+            if (node.getIndexInParent() == 0) {
+                return booleanCtx; // the condition
+            } else {
+                // a branch
+                if (isPreJava8()) {
+                    return RegularCtx.NO_CTX;
+                }
+                assert ((ASTConditionalExpression) papa).isStandalone()
+                    : "Expected standalone ternary, otherwise doesCascadeContext(..) would have returned true";
+
+                return ExprContext.newStandaloneTernaryCtx(((ASTConditionalExpression) papa).getTypeMirror());
+            }
 
         } else if (papa instanceof ASTInfixExpression) {
             // numeric contexts, maybe
@@ -503,7 +510,7 @@ final class PolyResolution {
             case OR:
             case XOR:
             case AND:
-                return ctxType == ts.BOOLEAN ? booleanCtx : ExprContext.newNumericContext(ctxType);
+                return ctxType == ts.BOOLEAN ? booleanCtx : ExprContext.newNumericContext(ctxType); // NOPMD CompareObjectsWithEquals
             case LEFT_SHIFT:
             case RIGHT_SHIFT:
             case UNSIGNED_RIGHT_SHIFT:
@@ -516,11 +523,16 @@ final class PolyResolution {
                     return ExprContext.newNonPolyContext(otherOperand.getTypeMirror().unbox());
                 }
                 return RegularCtx.NO_CTX;
+            case ADD:
+                if (TypeTestUtil.isA(String.class, ctxType)) {
+                    // string concat expr
+                    return stringCtx;
+                }
+                // fallthrough
             case LE:
             case GE:
             case GT:
             case LT:
-            case ADD:
             case SUB:
             case MUL:
             case DIV:
@@ -546,7 +558,10 @@ final class PolyResolution {
         } else if (isPreJava8()) {
             // in java < 8, context doesn't go flow through ternaries
             return false;
-        } else if (!internalUse && node instanceof ASTConditionalExpression) {
+        } else if (!internalUse
+            && node instanceof ASTConditionalExpression
+            && child.getIndexInParent() != 0) {
+            // conditional branch
             ((ASTConditionalExpression) node).getTypeMirror(); // force resolution
             return !((ASTConditionalExpression) node).isStandalone();
         }

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/codestyle/UnnecessaryCastRule.java

@@ -35,6 +35,7 @@ import net.sourceforge.pmd.lang.java.rule.internal.JavaRuleUtil;
 import net.sourceforge.pmd.lang.java.types.JTypeMirror;
 import net.sourceforge.pmd.lang.java.types.TypeConversion;
 import net.sourceforge.pmd.lang.java.types.TypeOps;
+import net.sourceforge.pmd.lang.java.types.TypeTestUtil;
 
 /**
  * Detects casts where the operand is already a subtype of the context
@@ -107,7 +108,7 @@ public class UnnecessaryCastRule extends AbstractJavaRulechainRule {
                 && operandType.isSubtypeOf(coercionType);
         }
 
-        return !isCastDeterminingContext(castExpr, context, coercionType)
+        return !isCastDeterminingContext(castExpr, context, coercionType, operandType)
             && castIsUnnecessaryToMatchContext(context, coercionType, operandType);
     }
 
@@ -126,14 +127,10 @@ public class UnnecessaryCastRule extends AbstractJavaRulechainRule {
         JTypeMirror contextType = context.getTargetType();
         if (contextType == null) {
             return false; // should not occur in valid code
-        }
-
-        if (!TypeConversion.isConvertibleUsingBoxing(operandType, coercionType)) {
+        } else if (!TypeConversion.isConvertibleUsingBoxing(operandType, coercionType)) {
             // narrowing cast
             return false;
-        }
-
-        if (!context.acceptsType(operandType)) {
+        } else if (!context.acceptsType(operandType)) {
             // then removing the cast would produce uncompilable code
             return false;
         }
@@ -149,30 +146,42 @@ public class UnnecessaryCastRule extends AbstractJavaRulechainRule {
      * that the cast is necessary, because there's some primitive conversions
      * happening, or some other corner case.
      */
-    private static boolean isCastDeterminingContext(ASTCastExpression castExpr, ExprContext context, @NonNull JTypeMirror coercionType) {
+    private static boolean isCastDeterminingContext(ASTCastExpression castExpr, ExprContext context, @NonNull JTypeMirror coercionType, JTypeMirror operandType) {
 
         if (castExpr.getParent() instanceof ASTConditionalExpression && castExpr.getIndexInParent() != 0) {
             // a branch of a ternary
             return true;
-        }
 
-        if (context.isNumeric() && castExpr.getParent() instanceof ASTInfixExpression) {
+        } else if (context.isString() && isInfixExprWithOperator(castExpr.getParent(), ADD)) {
+
+            // inside string concatenation
+            return !TypeTestUtil.isA(String.class, JavaRuleUtil.getOtherOperandIfInInfixExpr(castExpr))
+                && !TypeTestUtil.isA(String.class, operandType);
+
+        } else if (context.isNumeric() && castExpr.getParent() instanceof ASTInfixExpression) {
+            // numeric expr
             ASTInfixExpression parent = (ASTInfixExpression) castExpr.getParent();
 
             if (isInfixExprWithOperator(parent, SHIFT_OPS)) {
-                // then the cast is determining the width of expr
-                assert castExpr == parent.getLeftOperand(); // second operand doesn't have a numeric context
-                return true;
+                // if so, then the cast is determining the width of expr
+                // the right operand is always int
+                if (castExpr == parent.getLeftOperand()) {
+                    return !TypeOps.isStrictSubtype(operandType.unbox(), operandType.getTypeSystem().INT);
+                } else {
+                    return false;
+                }
             } else if (isInfixExprWithOperator(parent, BINARY_PROMOTED_OPS)) {
                 ASTExpression otherOperand = JavaRuleUtil.getOtherOperandIfInInfixExpr(castExpr);
+                JTypeMirror otherType = otherOperand.getTypeMirror();
 
-                return otherOperand instanceof ASTCastExpression // remove FPs
-                    // Ie, the type that is taken by the binary promotion
-                    // is the type of the cast, not the type of the operand.
-                    // Eg in
-                    //     int i; ((double) i) * i
-                    // the only reason the mult expr has type double is because of the cast
-                    || TypeOps.isStrictSubtype(otherOperand.getTypeMirror(), coercionType);
+                // Ie, the type that is taken by the binary promotion
+                // is the type of the cast, not the type of the operand.
+                // Eg in
+                //     int i; ((double) i) * i
+                // the only reason the mult expr has type double is because of the cast
+                return TypeOps.isStrictSubtype(otherType, coercionType)
+                    // but not for integers strictly smaller than int
+                    && !TypeOps.isStrictSubtype(otherType.unbox(), otherType.getTypeSystem().INT);
             }
 
         }

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/types/TypeSystem.java

@@ -212,7 +212,6 @@ public final class TypeSystem {
         FLOAT = createPrimitive(PrimitiveTypeKind.FLOAT, Float.class);
         DOUBLE = createPrimitive(PrimitiveTypeKind.DOUBLE, Double.class);
 
-        // this relies on the fact that setOf always returns immutable sets
         BOOLEAN.superTypes = immutableSetOf(BOOLEAN);
         CHAR.superTypes = immutableSetOf(CHAR, INT, LONG, FLOAT, DOUBLE);
         BYTE.superTypes = immutableSetOf(BYTE, SHORT, INT, LONG, FLOAT, DOUBLE);

pmd-java/src/test/kotlin/net/sourceforge/pmd/lang/java/types/internal/infer/ConversionContextTests.kt

@@ -6,9 +6,11 @@
 package net.sourceforge.pmd.lang.java.types.internal.infer
 
 import io.kotest.assertions.withClue
+import io.kotest.matchers.shouldBe
 import net.sourceforge.pmd.lang.ast.test.component6
 import net.sourceforge.pmd.lang.ast.test.shouldBe
 import net.sourceforge.pmd.lang.java.ast.*
+import net.sourceforge.pmd.lang.java.rule.internal.JavaRuleUtil
 import net.sourceforge.pmd.lang.java.types.STRING
 import net.sourceforge.pmd.lang.java.types.parseWithTypeInferenceSpy
 import net.sourceforge.pmd.lang.java.types.shouldHaveType
@@ -165,6 +167,23 @@ class ConversionContextTests : ProcessorTestSpec({
         }
     }
 
+    parserTest("Test context of ternary condition") {
+
+        val (acu, spy) = parser.parseWithTypeInferenceSpy("""
+            class Scratch {
+                static void m(Boolean boxedBool, boolean bool, String str, int[] ints) {
+                    str = (boolean) boxedBool ? "a" : "b";
+                }
+            }
+        """)
+
+        val (booleanCast) = acu.descendants(ASTCastExpression::class.java).toList()
+
+        spy.shouldBeOk {
+            booleanCast.conversionContext::getTargetType shouldBe boolean
+        }
+    }
+
     parserTest("Test numeric context") {
 
         val (acu, spy) = parser.parseWithTypeInferenceSpy("""
@@ -201,4 +220,30 @@ class ConversionContextTests : ProcessorTestSpec({
             }
         }
     }
+    parserTest("String contexts") {
+
+        val (acu, spy) = parser.parseWithTypeInferenceSpy("""
+            class Scratch {
+                static void m(int i) {
+                    eat(" " + i);
+                    eat(i + " ");
+                    eat(" " + " ");
+                    eat(" " + i + i);
+                }
+                void eat(Object d) {}
+            }
+        """)
+
+        val concats = acu.descendants(ASTInfixExpression::class.java).toList()
+
+        spy.shouldBeOk {
+            concats.forEach {
+                withClue(it) {
+                    JavaRuleUtil.isStringConcatExpr(it) shouldBe true
+                    it.leftOperand.conversionContext::getTargetType shouldBe ts.STRING
+                    it.rightOperand.conversionContext::getTargetType shouldBe ts.STRING
+                }
+            }
+        }
+    }
 })

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/ast/ParserCornerCases.txt

@@ -344,7 +344,7 @@
    |           |  |  +- VariableAccess[@AccessType = "READ", @CompileTimeConstant = "false", @Image = "i", @Name = "i", @ParenthesisDepth = "0", @Parenthesized = "false"]
    |           |  |  +- NumericLiteral[@Base = "10", @CompileTimeConstant = "true", @DoubleLiteral = "false", @FloatLiteral = "false", @Image = "10", @IntLiteral = "true", @Integral = "true", @LongLiteral = "false", @ParenthesisDepth = "0", @Parenthesized = "false", @ValueAsDouble = "10.0", @ValueAsFloat = "10.0", @ValueAsInt = "10", @ValueAsLong = "10"]
    |           |  +- ForUpdate[]
-   |           |  |  +- StatementExpressionList[]
+   |           |  |  +- StatementExpressionList[@Size = "1"]
    |           |  |     +- UnaryExpression[@CompileTimeConstant = "false", @Operator = "++", @ParenthesisDepth = "0", @Parenthesized = "false"]
    |           |  |        +- VariableAccess[@AccessType = "WRITE", @CompileTimeConstant = "false", @Image = "i", @Name = "i", @ParenthesisDepth = "0", @Parenthesized = "false"]
    |           |  +- Block[@Size = "0", @containsComment = "false"]

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/ast/ParserCornerCases18.txt

@@ -1075,7 +1075,7 @@
          |        |  +- MethodCall[@CompileTimeConstant = "false", @Image = "hasNext", @MethodName = "hasNext", @ParenthesisDepth = "0", @Parenthesized = "false"]
          |        |     +- ArgumentList[@Size = "0"]
          |        +- ForUpdate[]
-         |        |  +- StatementExpressionList[]
+         |        |  +- StatementExpressionList[@Size = "1"]
          |        |     +- UnaryExpression[@CompileTimeConstant = "false", @Operator = "--", @ParenthesisDepth = "0", @Parenthesized = "false"]
          |        |        +- VariableAccess[@AccessType = "WRITE", @CompileTimeConstant = "false", @Image = "i", @Name = "i", @ParenthesisDepth = "0", @Parenthesized = "false"]
          |        +- ExpressionStatement[]

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/codestyle/xml/UnnecessaryCast.xml

@@ -618,7 +618,7 @@ class Scratch {
             ]]></code>
     </test-code>
     <test-code>
-        <description>Loops</description>
+        <description>Conditionals and loop statements</description>
         <expected-problems>5</expected-problems>
         <code><![CDATA[
             class Scratch {
@@ -632,6 +632,30 @@ class Scratch {
             }
             ]]></code>
     </test-code>
+    <test-code>
+        <description>Conditional expr condition</description>
+        <expected-problems>1</expected-problems>
+        <code><![CDATA[
+            class Scratch {
+                static void m(Boolean boxedBool, boolean bool, String str, int[] ints) {
+                    str = (boolean) boxedBool ? "a" : "b";
+                }
+            }
+            ]]></code>
+    </test-code>
+    <test-code>
+        <description>Necessary cast for condition</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+            class Scratch {
+                static void m(Object obj) {
+                    // both are necessary
+                    if ((Boolean) obj
+                        || (boolean) obj);
+                }
+            }
+            ]]></code>
+    </test-code>
     <test-code>
         <description>Missing context identity cast</description>
         <expected-problems>2</expected-problems>
@@ -659,4 +683,118 @@ class Scratch {
             }
             ]]></code>
     </test-code>
+    <test-code>
+        <description>Casts in shift exprs</description>
+        <expected-problems>7</expected-problems>
+        <expected-linenumbers>5,8,9,10,12,13,14</expected-linenumbers>
+        <code><![CDATA[
+            class Scratch {
+                static void m(int i, short s, long l, Integer boxedInt) {
+                    l  = (long) i << 2; // "necessary"
+                    l  = (long) i << 34; // definitely necessary
+                    l  = (long) (i << 34); // unnecessary, l5
+
+                    i = i << (int) l;          // necessary
+                    i = i << (int) boxedInt;   // unnecessary
+                    i = (int) i << boxedInt;   // unnecessary
+                    i = (int) (i << boxedInt); // unnecessary
+
+                    i = (int) s << boxedInt;   // unnecessary, widened anyway
+                    i = ((int) s) << boxedInt; // unnecessary, same expression with unnecessary parens
+                    i = (int) (s << boxedInt); // unnecessary
+
+                }
+            }
+            ]]></code>
+    </test-code>
+    <test-code>
+        <description>Casts in arithmetic smaller than int </description>
+        <expected-problems>9</expected-problems>
+        <code><![CDATA[
+            class Scratch {
+                // they're all unecessary
+                static void m(int i, byte b, char c, short s) {
+                    i = b * (int) b; // 4
+                    i = (int) b * b;
+                    i = b * (int) s; // 6
+                    i = b * (int) c;
+                    i = b * (short) b; // 8
+                    i = i * (short) b;
+                    i = i * (short) s; // 10
+                    i = i * (int) c;
+                    i = i * (char) c; // 11
+                }
+            }
+            ]]></code>
+    </test-code>
+    <test-code>
+        <description>Casts in arithmetic with unboxing + widening</description>
+        <expected-problems>4</expected-problems>
+        <code><![CDATA[
+            class Scratch {
+                static void m(Integer i, Double d, Object lhs) {
+                    lhs = (int) i * 1.0;
+                    lhs = (double) d * 1.01;
+                    lhs = 1.01 * (int) i;
+                    lhs = 1.01 * (double) d;
+                }
+            }
+            ]]></code>
+    </test-code>
+    <test-code>
+        <description>"Narrowing" cast from char to short is necessary</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+            class Scratch {
+
+                static void m(int i, byte b, char c, short s) {
+                    i = i * (short) c;
+                }
+            }
+            ]]></code>
+    </test-code>
+    <test-code>
+        <description>char cast to int in string context is ok</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+            class Scratch {
+
+                static void m(String s, char c) {
+                    // the toString is different -> necessary (string contexts aren't implemented yet)
+                    s = "(" + (int) c + ")" + c;
+                }
+            }
+            ]]></code>
+    </test-code>
+    <test-code>
+        <description>String cast determining context</description>
+        <expected-problems>1</expected-problems>
+        <expected-linenumbers>5</expected-linenumbers>
+        <code><![CDATA[
+            class Scratch {
+                static void m(Object a, Object b) {
+                    String s = a + (String) b   // necessary, determines context
+                            + a + (String) b    // technically unnecessary, but narrowing
+                            + a + (String) null // unnecessary
+                            ;
+                }
+            }
+            ]]></code>
+    </test-code>
+    <test-code>
+        <description>Cast on both sides of arithmetic</description>
+        <expected-problems>1</expected-problems>
+        <expected-linenumbers>3</expected-linenumbers>
+        <expected-messages>
+            <message>Unnecessary cast (int)</message>
+        </expected-messages>
+        <code><![CDATA[
+            class Scratch {
+                static void m(short s, Object b) {
+                    b = (int) s
+                            + (long) s;
+                }
+            }
+            ]]></code>
+    </test-code>
 </test-data>

pom.xml

@@ -696,7 +696,7 @@
             <dependency>
                 <groupId>commons-io</groupId>
                 <artifactId>commons-io</artifactId>
-                <version>2.6</version>
+                <version>2.6</version> <!-- note: this is the last version compatible with java7 -->
             </dependency>
             <dependency>
                 <groupId>org.apache.commons</groupId>