Require data effects on non-copy parameters

Author: olwang

src/analyzer.rs

@@ -118,6 +118,25 @@ impl Analyzer<'_> {
                         ),
                     );
                 }
+                if param.effect.is_none() && !param.ty.name.is_empty() && !is_copy_type(&param.ty) {
+                    self.diagnostics.push(
+                        Diagnostic::error(
+                            code::MISSING_PARAMETER_EFFECT,
+                            format!(
+                                "parameter `{}` in `{}` must declare `read`, `mut`, or `take`.",
+                                param.name, function.name
+                            ),
+                            param.span.clone(),
+                            "missing parameter effect",
+                        )
+                        .with_cause("Non-Copy parameters must expose their data effect in the function signature.")
+                        .with_fix(
+                            "add_parameter_effect",
+                            format!("Write `{}: read {}` or another explicit effect.", param.name, type_ref_name(&param.ty)),
+                            "manual",
+                        ),
+                    );
+                }
             }
 
             for effect in &function.effects {
@@ -542,3 +561,41 @@ fn duplicate_symbol_label(kind: DuplicateSymbolKind) -> &'static str {
         DuplicateSymbolKind::Field => "field",
     }
 }
+
+fn is_copy_type(ty: &TypeRef) -> bool {
+    ty.args.is_empty()
+        && matches!(
+            ty.name.as_str(),
+            "Bool"
+                | "Byte"
+                | "Char"
+                | "Float"
+                | "Float32"
+                | "Float64"
+                | "Int"
+                | "Int8"
+                | "Int16"
+                | "Int32"
+                | "Int64"
+                | "UInt"
+                | "UInt8"
+                | "UInt16"
+                | "UInt32"
+                | "UInt64"
+                | "Unit"
+        )
+}
+
+fn type_ref_name(ty: &TypeRef) -> String {
+    if ty.args.is_empty() {
+        return ty.name.clone();
+    }
+
+    let args = ty
+        .args
+        .iter()
+        .map(type_ref_name)
+        .collect::<Vec<_>>()
+        .join(", ");
+    format!("{}<{args}>", ty.name)
+}

src/diagnostic.rs

@@ -8,6 +8,7 @@ pub mod code {
     pub const DUPLICATE_DECLARATION: &str = "RS0005";
     pub const DUPLICATE_FILE_MODE: &str = "RS0006";
     pub const UNKNOWN_RETAINED_PARAMETER: &str = "RS0007";
+    pub const MISSING_PARAMETER_EFFECT: &str = "RS0008";
     pub const FILE_MODE_VIOLATION: &str = "RS0101";
     pub const UNNAMED_ARGUMENT: &str = "RS0201";
     pub const MISSING_DATA_EFFECT: &str = "RS0202";
@@ -230,6 +231,11 @@ static DIAGNOSTIC_EXPLANATIONS: &[DiagnosticExplanation] = &[
         title: "unknown retained parameter",
         explanation: "`effects(retains(param))` must name a parameter declared by the function signature.",
     },
+    DiagnosticExplanation {
+        code: code::MISSING_PARAMETER_EFFECT,
+        title: "missing parameter data effect",
+        explanation: "Non-Copy parameters must declare `read`, `mut`, or `take` in the function signature so call effects are review-visible.",
+    },
     DiagnosticExplanation {
         code: code::FILE_MODE_VIOLATION,
         title: "file mode violation",

tests/fixtures/fail/missing-parameter-effect.rss

@@ -0,0 +1,10 @@
+// expect: RS0008
+mode: managed
+
+struct Image {
+    pixels: Buffer
+}
+
+fn inspect(image: Image) -> Unit {
+    Image.inspect(image: read image)
+}