introduce SpecType, fix #1739

grammars/go.bnf

@@ -242,11 +242,12 @@ private ExpressionListRecover ::= !('!' | '!=' | '%' | '%=' | '&&' | '&' | '&='
 
 TypeDeclaration ::= 'type' ( TypeSpec | '(' TypeSpecs? ')' ) {pin(".*")=1}
 private TypeSpecs ::= TypeSpec (semi TypeSpec)* semi? {pin=1}
-TypeSpec ::= identifier Type {
+TypeSpec ::= SpecType {
   pin=1
-  methods=[getGoTypeInner getMethods shouldGoDeeper]
+  methods=[getGoTypeInner getMethods shouldGoDeeper identifier="SpecType/identifier"]
   stubClass="com.goide.stubs.GoTypeSpecStub"
 }
+SpecType ::= identifier Type
 
 VarDeclaration ::= var ( VarSpec | '(' VarSpecs? ')' ) {pin=1}
 private VarSpecs ::= VarSpec (semi VarSpec)* semi? {pin=1}

src/com/goide/completion/GoCompletionUtil.java

@@ -202,7 +202,7 @@ public static LookupElement createTypeConversionLookupElement(@NotNull GoTypeSpe
 
   @NotNull
   public static InsertHandler<LookupElement> getTypeConversionInsertHandler(@NotNull GoTypeSpec t) {
-    GoType type = t.getType();
+    GoType type = t.getSpecType().getType();
     return type instanceof GoStructType || type instanceof GoArrayOrSliceType || type instanceof GoMapType
            ? BracesInsertHandler.ONE_LINER
            : ParenthesesInsertHandler.WITH_PARAMETERS;

src/com/goide/completion/GoKeywordCompletionContributor.java

@@ -116,7 +116,7 @@ private static ElementPattern<? extends PsiElement> insideSwitchStatement() {
 
   private static ElementPattern<? extends PsiElement> typeDeclaration() {
     return psiElement(GoTypes.IDENTIFIER)
-      .withParent(psiElement(GoTypeReferenceExpression.class).withParent(psiElement(GoType.class).withParent(GoTypeSpec.class)));
+      .withParent(psiElement(GoTypeReferenceExpression.class).withParent(psiElement(GoType.class).withParent(GoSpecType.class)));
   }
 
   private static PsiElementPattern.Capture<PsiElement> insideGoOrDeferStatements(@NotNull IElementType tokenType) {

src/com/goide/editor/GoFoldingBuilder.java

@@ -71,7 +71,7 @@ public FoldingDescriptor[] buildFoldRegions(@NotNull PsiElement root, @NotNull D
     }
 
     for (GoTypeSpec type : file.getTypes()) {
-      foldTypes(type.getType(), result);
+      foldTypes(type.getSpecType().getType(), result);
     }
 
     if (!quick) {

src/com/goide/psi/impl/GoFieldNameReference.java

@@ -65,12 +65,12 @@ public boolean execute(@NotNull PsiElement psiElement, @NotNull ResolveState res
   }
 
   @Nullable
-  private GoType getType(GoType type) { // todo: rethink and unify this algorithm
+  private GoType getType(@Nullable GoType type) { // todo: rethink and unify this algorithm
     boolean inValue = myValue != null;
 
     if (inValue && type instanceof GoArrayOrSliceType) type = ((GoArrayOrSliceType)type).getType();
     else if (type instanceof GoMapType) type = inValue ? ((GoMapType)type).getValueType() : ((GoMapType)type).getKeyType();
-    else if (inValue && type instanceof GoStructType) {
+    else if (inValue && type instanceof GoSpecType && ((GoSpecType)type).getType() instanceof GoStructType) {
       GoKey key = PsiTreeUtil.getPrevSiblingOfType(myValue, GoKey.class);
       GoFieldName field = key != null ? key.getFieldName() : null;
       PsiReference reference = field != null ? field.getReference() : null;
@@ -91,7 +91,7 @@ else if (inValue && type instanceof GoStructType) {
       }
     }
 
-    return type;
+    return type instanceof GoSpecType ? ((GoSpecType)type).getType() : type;
   }
 
   @Nullable

src/com/goide/psi/impl/GoNamedElementImpl.java

@@ -49,8 +49,7 @@
 
 import javax.swing.*;
 
-public abstract class GoNamedElementImpl<T extends GoNamedStub<?>> extends GoStubbedElementImpl<T>
-  implements GoCompositeElement, GoNamedElement {
+public abstract class GoNamedElementImpl<T extends GoNamedStub<?>> extends GoStubbedElementImpl<T> implements GoCompositeElement, GoNamedElement {
 
   public GoNamedElementImpl(@NotNull T stub, @NotNull IStubElementType nodeType) {
     super(stub, nodeType);

src/com/goide/psi/impl/GoPsiImplUtil.java

@@ -363,6 +363,7 @@ else if (o instanceof GoIndexOrSliceExpr) {
       if (typeRef != null) {
         type = getType(typeRef);
       }
+      if (type instanceof GoSpecType) type = ((GoSpecType)type).getType();
       if (type instanceof GoMapType) {
         List<GoType> list = ((GoMapType)type).getTypeList();
         if (list.size() == 2) {
@@ -411,7 +412,7 @@ public boolean value(GoTypeSpec spec) {
         }
       });
       if (str != null) {
-        return str.getType();
+        return str.getSpecType(); // todo
       }
     }
     return null;
@@ -507,7 +508,7 @@ public boolean shouldGoDeeper() {
   public static GoType getType(@Nullable GoTypeReferenceExpression expression) {
     PsiReference reference = expression != null ? expression.getReference() : null;
     PsiElement resolve = reference != null ? reference.resolve() : null;
-    return resolve instanceof GoTypeSpec ? ((GoTypeSpec)resolve).getType() : null;
+    return resolve instanceof GoTypeSpec ? ((GoTypeSpec)resolve).getSpecType() : null;
   }
 
   public static boolean isVariadic(@NotNull GoParamDefinition o) {
@@ -522,7 +523,7 @@ public static boolean isVariadic(@NotNull GoParameterDeclaration o) {
 
   @Nullable
   public static GoType getGoTypeInner(@NotNull GoTypeSpec o, @SuppressWarnings("UnusedParameters") @Nullable ResolveState context) {
-    return o.getType();
+    return o.getSpecType();
   }
 
   @Nullable
@@ -565,7 +566,10 @@ private static GoType findTypeInVarSpec(@NotNull GoVarDefinition o, @Nullable Re
     if (exprs.size() == 1 && exprs.get(0) instanceof GoCallExpr) {
       GoExpression call = exprs.get(0);
       GoType fromCall = call.getGoType(context);
-      GoType type = funcType(typeFromRefOrType(fromCall));
+      boolean canDecouple = varList.size() > 1;
+      GoType underlyingType = canDecouple && fromCall instanceof GoSpecType ? ((GoSpecType)fromCall).getType() : fromCall;
+      GoType byRef = typeFromRefOrType(underlyingType);
+      GoType type = funcType(canDecouple && byRef instanceof GoSpecType ? ((GoSpecType)byRef).getType() : byRef);
       if (type == null) return fromCall;
       if (type instanceof GoTypeList) {
         if (((GoTypeList)type).getTypeList().size() > i) {
@@ -607,7 +611,7 @@ private static GoType processRangeClause(@NotNull GoVarDefinition o, @NotNull Go
       if (typeRef != null) {
         PsiElement resolve = typeRef.getReference().resolve();
         if (resolve instanceof GoTypeSpec) {
-          type = ((GoTypeSpec)resolve).getType();
+          type = ((GoTypeSpec)resolve).getSpecType().getType();
           if (type instanceof GoChannelType) {
             return ((GoChannelType)type).getType();
           }
@@ -680,6 +684,11 @@ public Result<List<GoMethodDeclaration>> compute() {
     return calcMethods(o);
   }
 
+  @NotNull
+  public PsiElement getType(@NotNull GoTypeSpec o) {
+    return o.getSpecType();
+  }
+
   @NotNull
   private static List<GoMethodDeclaration> calcMethods(@NotNull GoTypeSpec o) {
     PsiFile file = o.getContainingFile().getOriginalFile();