Fix project file override

Source/DafnyDriver/Commands/CommandRegistry.cs

@@ -171,7 +171,7 @@ async Task CommandHandler(InvocationContext context) {
         object value;
         if (option.Arity.MaximumNumberOfValues <= 1) {
           // If multiple values aren't allowed, CLI options take precedence over project file options
-          value = result == null && hasProjectFileValue
+          value = (result == null || Equals(result.Token, null)) && hasProjectFileValue
             ? projectFileValue
             : GetValueForOption(context.ParseResult, option);
         } else {

Test/cli/projectFile/projectFile.dfy

@@ -7,6 +7,9 @@
 // Test option override behavior
 // RUN: %baredafny resolve --show-snippets:false --use-basename-for-filename "%S/dfyconfig.toml" --warn-shadowing=false >> "%t"
 
+// Test option with default override behavior
+// RUN: ! %baredafny resolve --show-snippets:false --use-basename-for-filename "%S/dfyconfig.toml" --function-syntax=3 >> "%t"
+
 // Multiple project files are not allowed
 // RUN: ! %baredafny resolve --show-snippets:false --use-basename-for-filename "%S/dfyconfig.toml" "%S/broken/dfyconfig.toml"
 

Test/cli/projectFile/projectFile.dfy.expect

@@ -3,6 +3,8 @@ input.dfy(6,8): Warning: Shadowed local-variable name: x
 Dafny program verifier did not attempt verification
 
 Dafny program verifier did not attempt verification
+input.dfy(10,0): Error: a function cannot be declared 'ghost' (it is 'ghost' by default when using --function-syntax:3)
+1 parse errors detected in input.dfy
 Warning: only Dafny project files named dfyconfig.toml are recognised by the Dafny IDE.
 Warning: option 'does-not-exist' that was specified in the project file, is not a valid Dafny option.
 

Test/cli/projectFile/src/input.dfy

@@ -5,4 +5,8 @@ method Foo() {
   if (true) {
     var x := 4;
   }
-}
+}
+
+ghost function Bar(): int {
+  3
+} 

docs/dev/news/4357.fix

@@ -0,0 +1 @@
+Allow function-syntax and other options with a custom default to be overridden in `dfyconfig.toml`