use `isCallableWithArg` in paren completion

For consistency and to allow future changes to type matching (e.g.
implicit type conversion)

src/dcd/server/autocomplete/ufcs.d

@@ -107,16 +107,18 @@ DSymbol*[] getSymbolsForUFCS(Scope* completionScope, const(DSymbol)* beforeDotSy
 }
 
 /**
-   Params:
-   symbol = the symbol to check
-   incomingSymbol = symbols we check on
-   Returns:
-   true if incomingSymbols first parameter matches beforeDotSymbol
-   false otherwise
-*/
-bool isCallableWithArg(const(DSymbol)* incomingSymbol, const(DSymbol)* beforeDotSymbol, bool isGlobalScope = false)
+ * Params:
+ *     incomingSymbol = the function symbol to check if it is valid for UFCS with `beforeDotType`.
+ *     beforeDotType = the type of the expression that's used before the dot.
+ *     isGlobalScope = the symbol to check
+ * Returns:
+ *     `true` if `incomingSymbols`' first parameter matches `beforeDotType`
+ *     `false` otherwise
+ */
+bool isCallableWithArg(const(DSymbol)* incomingSymbol, const(DSymbol)* beforeDotType, bool isGlobalScope = false)
 {
-    if (isGlobalScope && incomingSymbol.protection == tok!"private")
+    if (!incomingSymbol || !beforeDotType
+        || (isGlobalScope && incomingSymbol.protection == tok!"private"))
     {
         return false;
     }
@@ -124,7 +126,7 @@ bool isCallableWithArg(const(DSymbol)* incomingSymbol, const(DSymbol)* beforeDot
     if (incomingSymbol.kind == CompletionKind.functionName && !incomingSymbol
         .functionParameters.empty)
     {
-        return incomingSymbol.functionParameters.front.type is beforeDotSymbol;
+        return incomingSymbol.functionParameters.front.type is beforeDotType;
     }
 
     return false;
@@ -181,11 +183,11 @@ void getUFCSParenCompletion(ref DSymbol*[] symbols, Scope* completionScope, istr
     foreach(nextSymbol; possibleUFCSSymbol){
         if (nextSymbol && nextSymbol.functionParameters)
         {
-            if (firstSymbol.type is nextSymbol.functionParameters.front.type)
+            if (nextSymbol.isCallableWithArg(firstSymbol.type))
             {
                 nextSymbol.kind = CompletionKind.ufcsName;
                 symbols ~= nextSymbol;
             }
         }
     }
-}
+}

tests/tc_ufcs_calltip_in_func/file.d

@@ -1,5 +1,9 @@
 void showSomething(int x, string message, bool ok){}
 void showSomething(int x, string message, bool ok, float percentage){}
+void showSomething(string x, string message, bool ok){}
+void showSomething(){}
+int showSomething;
+struct showSomething { int x; }
 
 void main(){
 	int x;

tests/tc_ufcs_calltip_in_func/run.sh

@@ -1,5 +1,5 @@
 set -e
 set -u
 
-../../bin/dcd-client $1 -c163 file.d > actual.txt
+../../bin/dcd-client $1 -c293 file.d > actual.txt
 diff actual.txt expected.txt