IDEA-138441 Methods named like getters are wrongly treated as pure

don't track state for primitive get* methods
for reference-typed methods, track state only inside "if (getX() != null) ..."
flush dfa variables on non-pure getter-like calls

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java

@@ -650,10 +650,12 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
       return true;
     }
 
+    // track "x" property state only inside "if (getX() != null) ..."
+    if (dfaLeft instanceof DfaVariableValue && ((DfaVariableValue)dfaLeft).containsCalls() && (!isNull(dfaRight) || !isNegated)) {
+      return true;
+    }
+    
     if (dfaLeft == dfaRight) {
-      if (dfaLeft instanceof DfaVariableValue && ((DfaVariableValue)dfaLeft).containsCalls()) {
-        return true;
-      }
       return !isNegated;
     }
 

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/instructions/MethodCallInstruction.java

@@ -27,7 +27,6 @@ package com.intellij.codeInspection.dataFlow.instructions;
 import com.intellij.codeInspection.dataFlow.*;
 import com.intellij.codeInspection.dataFlow.value.DfaValue;
 import com.intellij.psi.*;
-import com.intellij.psi.util.PropertyUtil;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -126,7 +125,7 @@ public class MethodCallInstruction extends Instruction {
 
   private boolean isPureCall() {
     if (myTargetMethod == null) return false;
-    return ControlFlowAnalyzer.isPure(myTargetMethod) || PropertyUtil.isSimplePropertyGetter(myTargetMethod);
+    return ControlFlowAnalyzer.isPure(myTargetMethod);
   }
 
   @Nullable

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaExpressionFactory.java

@@ -21,6 +21,7 @@ import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.Condition;
 import com.intellij.openapi.util.Conditions;
 import com.intellij.openapi.util.registry.Registry;
+import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.*;
 import com.intellij.psi.impl.JavaConstantExpressionEvaluator;
 import com.intellij.psi.util.PropertyUtil;
@@ -41,18 +42,21 @@ public class DfaExpressionFactory {
 
   private static Condition<String> parseFalseGetters() {
     try {
-      final Pattern pattern = Pattern.compile(Registry.stringValue("ide.dfa.getters.with.side.effects"));
-      return new Condition<String>() {
-        @Override
-        public boolean value(String s) {
-          return pattern.matcher(s).matches();
-        }
-      };
+      String regex = Registry.stringValue("ide.dfa.getters.with.side.effects").trim();
+      if (!StringUtil.isEmpty(regex)) {
+        final Pattern pattern = Pattern.compile(regex);
+        return new Condition<String>() {
+          @Override
+          public boolean value(String s) {
+            return pattern.matcher(s).matches();
+          }
+        };
+      }
     }
     catch (Exception e) {
       LOG.error(e);
-      return Conditions.alwaysFalse();
     }
+    return Conditions.alwaysFalse();
   }
 
   private final DfaValueFactory myFactory;
@@ -152,10 +156,11 @@ public class DfaExpressionFactory {
       return (PsiVariable)target;
     }
     if (target instanceof PsiMethod) {
-      if (PropertyUtil.isSimplePropertyGetter((PsiMethod)target)) {
-        String qName = PsiUtil.getMemberQualifiedName((PsiMethod)target);
+      PsiMethod method = (PsiMethod)target;
+      if (PropertyUtil.isSimplePropertyGetter(method) && !(method.getReturnType() instanceof PsiPrimitiveType)) {
+        String qName = PsiUtil.getMemberQualifiedName(method);
         if (qName == null || !FALSE_GETTERS.value(qName)) {
-          return (PsiMethod)target;
+          return method;
         }
       }
     }

java/java-tests/testData/inspection/dataFlow/fixture/FalseGetters.java

@@ -0,0 +1,21 @@
+class A {
+  private String s;
+  private int next = 0;
+
+  public A(final String s) {
+    this.s = s;
+  }
+
+  private char getChar() {
+    return s.charAt(next++);
+  }
+
+  private void foo() {
+    char c = getChar();
+    if (c == 'a') {
+      if (getChar() == 'b') {
+        System.out.println("ab");
+      }
+    }
+  }
+}

java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java

@@ -271,6 +271,7 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
   public void testUnusedCallDoesNotMakeUnknown() { doTest(); }
   public void testEmptyCallDoesNotMakeNullable() { doTest(); }
   public void testGettersAndPureNoFlushing() { doTest(); }
+  public void testFalseGetters() { doTest(); }
   
   public void testNotNullAfterDereference() { doTest(); }
 

platform/util/resources/misc/registry.properties

@@ -294,7 +294,7 @@ ide.structural.navigation.visit.fields.description=Whether fields should be stop
 ide.non.english.keyboard.layout.fix=false
 ide.non.english.keyboard.layout.fix.description=Enables a fix for key codes with non-English keyboard layouts
 
-ide.dfa.getters.with.side.effects=java\\.nio\\..*ByteBuffer\\.get.*
+ide.dfa.getters.with.side.effects=
 ide.dfa.getters.with.side.effects.description=A regex on qualified names of methods that look like getters but are not. For Constant Conditions & Exception inspection
 
 ide.dfa.time.limit.online=1000