Introduce 'mayHaveContract'-flag in stubs

This is needed for further commit, which supports contracts-based
smartcasts in partial body resolve mode.

NB: Stubs can be built from 3 sources:
- source code (contract presence can be checked by PSI)
- binary data (contract presence can be checked by Kotlin Metadata)
- decompiled sources

The last case is a bit of a headache, because usually bodies are omitted
in decompiled sources. To workaround it, we have to inject stubbed
contract-call in the body.

compiler/psi/src/org/jetbrains/kotlin/psi/KtNamedFunction.java

@@ -26,6 +26,7 @@ import com.intellij.psi.util.PsiTreeUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.lexer.KtTokens;
+import org.jetbrains.kotlin.psi.psiUtil.KtPsiUtilKt;
 import org.jetbrains.kotlin.psi.stubs.KotlinFunctionStub;
 import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes;
 import org.jetbrains.kotlin.psi.typeRefHelpers.TypeRefHelpersKt;
@@ -219,4 +220,13 @@ public class KtNamedFunction extends KtTypeParameterListOwnerStub<KotlinFunction
         // Suppress Java check for out-of-block
         return false;
     }
+
+    public boolean mayHaveContract() {
+        KotlinFunctionStub stub = getStub();
+        if (stub != null) {
+            return stub.mayHaveContract();
+        }
+
+        return KtPsiUtilKt.isContractPresentPsiCheck(this);
+    }
 }

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/StubInterfaces.kt

@@ -69,6 +69,7 @@ interface KotlinFunctionStub : KotlinCallableStubBase<KtNamedFunction> {
     fun hasBlockBody(): Boolean
     fun hasBody(): Boolean
     fun hasTypeParameterListBeforeFunctionName(): Boolean
+    fun mayHaveContract(): Boolean
 }
 
 interface KotlinImportAliasStub : StubElement<KtImportAlias> {

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/elements/KtFunctionElementType.java

@@ -46,7 +46,8 @@ public class KtFunctionElementType extends KtStubElementType<KotlinFunctionStub,
         boolean hasBlockBody = psi.hasBlockBody();
         boolean hasBody = psi.hasBody();
         return new KotlinFunctionStubImpl(parentStub, StringRef.fromString(psi.getName()), isTopLevel, fqName,
-                                          isExtension, hasBlockBody, hasBody, psi.hasTypeParameterListBeforeFunctionName());
+                                          isExtension, hasBlockBody, hasBody, psi.hasTypeParameterListBeforeFunctionName(),
+                                          psi.mayHaveContract());
     }
 
     @Override
@@ -61,6 +62,7 @@ public class KtFunctionElementType extends KtStubElementType<KotlinFunctionStub,
         dataStream.writeBoolean(stub.hasBlockBody());
         dataStream.writeBoolean(stub.hasBody());
         dataStream.writeBoolean(stub.hasTypeParameterListBeforeFunctionName());
+        dataStream.writeBoolean(stub.mayHaveContract());
     }
 
     @NotNull
@@ -76,9 +78,10 @@ public class KtFunctionElementType extends KtStubElementType<KotlinFunctionStub,
         boolean hasBlockBody = dataStream.readBoolean();
         boolean hasBody = dataStream.readBoolean();
         boolean hasTypeParameterListBeforeFunctionName = dataStream.readBoolean();
+        boolean mayHaveContract = dataStream.readBoolean();
 
         return new KotlinFunctionStubImpl(parentStub, name, isTopLevel, fqName, isExtension, hasBlockBody, hasBody,
-                                          hasTypeParameterListBeforeFunctionName);
+                                          hasTypeParameterListBeforeFunctionName, mayHaveContract);
     }
 
     @Override

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinFunctionStubImpl.kt

@@ -32,7 +32,8 @@ class KotlinFunctionStubImpl(
     private val isExtension: Boolean,
     private val hasBlockBody: Boolean,
     private val hasBody: Boolean,
-    private val hasTypeParameterListBeforeFunctionName: Boolean
+    private val hasTypeParameterListBeforeFunctionName: Boolean,
+    private val mayHaveContract: Boolean
 ) : KotlinStubBaseImpl<KtNamedFunction>(parent, KtStubElementTypes.FUNCTION), KotlinFunctionStub {
     init {
         if (isTopLevel && fqName == null) {
@@ -48,4 +49,5 @@ class KotlinFunctionStubImpl(
     override fun hasBlockBody() = hasBlockBody
     override fun hasBody() = hasBody
     override fun hasTypeParameterListBeforeFunctionName() = hasTypeParameterListBeforeFunctionName
+    override fun mayHaveContract(): Boolean = mayHaveContract
 }