Add sanity checks when creating function parameter type (rust-lang#532)

Author: danielsn

compiler/cbmc/src/goto_program/symbol.rs

@@ -289,7 +289,7 @@ impl Symbol {
 impl Symbol {
     /// Makes a formal function parameter from a symbol.
     pub fn to_function_parameter(&self) -> Parameter {
-        Type::parameter(Some(self.name.to_string()), self.base_name.clone(), self.typ.clone())
+        self.typ.clone().as_parameter(Some(self.name.to_string()), self.base_name.clone())
     }
 
     /// Makes an expression from a symbol.

compiler/cbmc/src/goto_program/symtab_transformer/gen_c_transformer/name_transformer.rs

@@ -144,10 +144,9 @@ impl Transformer for NameTransformer {
 
     /// Normalize parameter identifier.
     fn transform_type_parameter(&mut self, parameter: &Parameter) -> Parameter {
-        Type::parameter(
+        self.transform_type(parameter.typ()).as_parameter(
             parameter.identifier().map(|name| self.normalize_identifier(name)),
             parameter.base_name().map(|name| self.normalize_identifier(name)),
-            self.transform_type(parameter.typ()),
         )
     }
 

compiler/cbmc/src/goto_program/symtab_transformer/transformer.rs

@@ -97,11 +97,8 @@ pub trait Transformer: Sized {
 
     /// Transforms a parameter for a function
     fn transform_type_parameter(&mut self, parameter: &Parameter) -> Parameter {
-        Type::parameter(
-            parameter.identifier().cloned(),
-            parameter.base_name().cloned(),
-            self.transform_type(parameter.typ()),
-        )
+        self.transform_type(parameter.typ())
+            .as_parameter(parameter.identifier().cloned(), parameter.base_name().cloned())
     }
 
     /// Transforms a function type (`return_type x(parameters)`)

compiler/cbmc/src/goto_program/typ.rs

@@ -423,6 +423,34 @@ impl Type {
         }
     }
 
+    pub fn is_lvalue(&self) -> bool {
+        match self {
+            Bool
+            | CBitField { .. }
+            | CInteger(_)
+            | Double
+            | Float
+            | Pointer { .. }
+            | Signedbv { .. }
+            | Struct { .. }
+            | StructTag(_)
+            | Union { .. }
+            | UnionTag(_)
+            | Unsignedbv { .. }
+            | Vector { .. } => true,
+
+            Array { .. }
+            | Code { .. }
+            | Constructor
+            | Empty
+            | FlexibleArray { .. }
+            | IncompleteStruct { .. }
+            | IncompleteUnion { .. }
+            | InfiniteArray { .. }
+            | VariadicCode { .. } => false,
+        }
+    }
+
     /// Is the current type either an integer or a floating point?
     pub fn is_numeric(&self) -> bool {
         self.is_floating_point() || self.is_integer()
@@ -543,6 +571,22 @@ impl Type {
         CBitField { width, typ: Box::new(self) }
     }
 
+    /// A formal function parameter.
+    /// identifier: The unique identifier that refers to this parameter `foo12_bar17_x@1`
+    /// base_name: the local name of the parameter within the function `x`
+    /// typ: The type of the parameter
+    pub fn as_parameter(self, identifier: Option<String>, base_name: Option<String>) -> Parameter {
+        // FIXME: https://github.com/model-checking/rmc/issues/570
+        assert!(
+            self.is_empty() || self.is_lvalue(),
+            "Expected lvalue from {:?} {:?} {:?}",
+            self,
+            identifier,
+            base_name
+        );
+        Parameter { identifier, base_name, typ: self }
+    }
+
     pub fn bool() -> Self {
         Bool
     }
@@ -568,10 +612,7 @@ impl Type {
     /// CBMC, like c, allows function types to have unnamed formal paramaters
     /// `int foo(int, char, double)`
     pub fn code_with_unnamed_parameters(param_types: Vec<Type>, return_type: Type) -> Self {
-        let parameters = param_types
-            .into_iter()
-            .map(|t| Parameter { identifier: None, base_name: None, typ: t })
-            .collect();
+        let parameters = param_types.into_iter().map(|t| t.as_parameter(None, None)).collect();
         Type::code(parameters, return_type)
     }
 
@@ -618,18 +659,6 @@ impl Type {
         Float
     }
 
-    /// A formal function parameter.
-    /// identifier: The unique identifier that refers to this parameter `foo12_bar17_x@1`
-    /// base_name: the local name of the parameter within the function `x`
-    /// typ: The type of the parameter
-    pub fn parameter(
-        identifier: Option<String>,
-        base_name: Option<String>,
-        typ: Type,
-    ) -> Parameter {
-        Parameter { identifier, base_name, typ }
-    }
-
     /// A forward declared struct.
     /// struct foo;
     pub fn incomplete_struct(name: &str) -> Self {

compiler/cbmc/src/irep/from_irep.rs

@@ -124,8 +124,8 @@ impl FromIrep for Parameter {
         assert!(i.sub.is_empty());
         let identifier = i.lookup_as_string(IrepId::CIdentifier);
         let base_name = i.lookup_as_string(IrepId::CBaseName);
-        let typ = FromIrep::from_irep(i.lookup(IrepId::Type).unwrap());
-        Type::parameter(identifier, base_name, typ)
+        let typ: Type = FromIrep::from_irep(i.lookup(IrepId::Type).unwrap());
+        typ.as_parameter(identifier, base_name)
     }
 }
 

compiler/rustc_codegen_rmc/src/codegen/typ.rs

@@ -1202,7 +1202,7 @@ impl<'tcx> GotocCtx<'tcx> {
                             ident = name;
                         }
                     }
-                    Some(Type::parameter(Some(ident.to_string()), Some(ident), self.codegen_ty(*t)))
+                    Some(self.codegen_ty(*t).as_parameter(Some(ident.to_string()), Some(ident)))
                 }
             })
             .collect();
@@ -1214,7 +1214,7 @@ impl<'tcx> GotocCtx<'tcx> {
             if let Some(self_param) = params.first() {
                 let ident = self_param.identifier().map(|i| i.to_string());
                 let ty = self_param.typ().clone();
-                params[0] = Type::parameter(ident.clone(), ident, ty.to_pointer());
+                params[0] = ty.to_pointer().as_parameter(ident.clone(), ident);
             }
         }