Do not report an undefined function warning if the function name is a variable

Summary: Counterpart of the previous fix. Do not report potentially false positives in case a function is a variable.

Reviewed By: alanz

Differential Revision: D84832054

fbshipit-source-id: 4a0b2fde715da4bfcab83f802d95da1a31a797ff

Author: robertoaloi

crates/ide/src/diagnostics/undefined_function.rs

@@ -76,7 +76,7 @@ impl FunctionCallLinter for UndefinedFunctionLinter {
 
                 // If the module is a variable, we can't determine at compile time
                 // whether the function is defined or not, so don't report it
-                if module.as_var().is_some() {
+                if module.as_var().is_some() || name.as_var().is_some() {
                     return None;
                 }
 
@@ -401,4 +401,16 @@ exists() -> ok.
             "#,
         )
     }
+
+    #[test]
+    fn test_function_name_variable() {
+        check_diagnostics(
+            r#"
+    //- /src/main.erl
+    -module(main).
+    main(Callback) ->
+      main:Callback().
+            "#,
+        )
+    }
 }