Adding alias this to symbol and match algorithm

dsymbol/src/dsymbol/conversion/second.d

@@ -362,6 +362,9 @@ void resolveAliasThis(DSymbol* symbol,
 		auto parts = symbol.getPartsByName(aliasThis.breadcrumbs.front);
 		if (parts.length == 0 || parts[0].type is null)
 			continue;
+
+		symbol.aliasThisSymbol = parts[0];
+
 		DSymbol* s = GCAllocator.instance.make!DSymbol(IMPORT_SYMBOL_NAME,
 			CompletionKind.importSymbol, parts[0].type);
 		symbol.addChild(s, true);

dsymbol/src/dsymbol/symbol.d

@@ -375,6 +375,8 @@ struct DSymbol
 	// TODO: assert that the type is not a function
 	DSymbol* type;
 
+	// Is using alias this
+	DSymbol* aliasThisSymbol;
 	/**
 	 * Names of function arguments
 	 */

src/dcd/server/autocomplete/ufcs.d

@@ -13,7 +13,6 @@ import std.string;
 import dparse.lexer : tok;
 import std.regex;
 import containers.hashset : HashSet;
-import dparse.ast;
 
 // https://dlang.org/spec/type.html#implicit-conversions
 enum string[string] INTEGER_PROMOTIONS = [
@@ -121,8 +120,6 @@ DSymbol*[] getSymbolsForUFCS(Scope* completionScope, const(DSymbol)* beforeDotSy
 
 bool willImplicitBeUpcasted(string from, string to)
 {
-    import std.stdio;
-
     string* found = from in INTEGER_PROMOTIONS;
     if (!found)
     {
@@ -132,6 +129,14 @@ bool willImplicitBeUpcasted(string from, string to)
     return INTEGER_PROMOTIONS[from] == to;
 }
 
+bool matchAliasThis(const(DSymbol)* aliasThisSymbol, const(DSymbol)* incomingSymbol)
+{
+    if(aliasThisSymbol) {
+        return isCallableWithArg(incomingSymbol, aliasThisSymbol.type);
+    }
+    return false;
+}
+
 /**
  * Params:
  *     incomingSymbol = the function symbol to check if it is valid for UFCS with `beforeDotType`.
@@ -152,8 +157,10 @@ bool isCallableWithArg(const(DSymbol)* incomingSymbol, const(DSymbol)* beforeDot
     if (incomingSymbol.kind == CompletionKind.functionName && !incomingSymbol
         .functionParameters.empty)
     {
-        return beforeDotType is incomingSymbol.functionParameters.front.type ||
+        return beforeDotType is incomingSymbol.functionParameters.front.type 
-            willImplicitBeUpcasted(beforeDotType.name, incomingSymbol.functionParameters.front.type.name);
+            || willImplicitBeUpcasted(beforeDotType.name, incomingSymbol.functionParameters.front.type.name) 
+            || matchAliasThis(beforeDotType.aliasThisSymbol, incomingSymbol);
+
     }
 
     return false;

tests/tc_ufcs_struct_completion/expected_aliased_struct_test.txt

@@ -0,0 +1,12 @@
+identifiers
+alignof	k
+init	k
+mangleof	k
+max	k
+min	k
+sizeof	k
+stringof	k
+tupleof	k
+ufcsSomeInt	F
+ufcsSomeShort	F
+x	v

tests/tc_ufcs_struct_completion/fooutils/fooutils.d

@@ -5,7 +5,7 @@ struct Foo {
 }
 
 struct IntAliased {
-    int x;
+    short x;
     alias x this;
 }
 
@@ -19,4 +19,5 @@ void ufcsBarRefImmuttableWrapped(ref immutable(Foo) foo, string mama) {}
 void ufcsBarScope(ref scope Foo foo, string mama) {}
 void ufcsBarReturnScope(return scope Foo foo, string mama) {}
 void ufcsSomeInt(int x) {}
+void ufcsSomeShort(short x) {}
 private void ufcsBarPrivate(Foo foo, string message) {}