HACK: transpile: use dashmap to enable interior mutability for TypedAstContext::c_types

note: this is a hack because it adds a memory leak in the `Index` impl

Author: fw-immunant

Cargo.lock

@@ -18,6 +18,7 @@ c2rust-ast-printer = { path = "../c2rust-ast-printer", version = "0.22.1" }
 c2rust-bitfields = { path = "../c2rust-bitfields", version = "0.22.1" }
 c2rust-rust-tools = { path = "../c2rust-rust-tools", version = "0.22.1" }
 colored = "2.0"
+dashmap = "4.0"
 dtoa = "1.0"
 failure = "0.1.5"
 fern = { version = "0.6", features = ["colored"] }

c2rust-transpile/Cargo.toml

@@ -47,7 +47,7 @@ pub type CEnumConstantId = CDeclId; // Enum's need to point to child 'DeclKind::
 pub struct TypedAstContext {
     main_file: PathBuf,
 
-    c_types: HashMap<CTypeId, CType>,
+    c_types: dashmap::DashMap<CTypeId, CType>,
     c_exprs: HashMap<CExprId, CExpr>,
     c_stmts: HashMap<CStmtId, CStmt>,
 
@@ -1050,11 +1050,16 @@ impl TypedAstContext {
                 use SomeId::*;
                 match some_id {
                     Type(type_id) => {
-                        if let CTypeKind::Elaborated(decl_type_id) = self.c_types[&type_id].kind {
+                        if let CTypeKind::Elaborated(decl_type_id) =
+                            self.c_types.get(&type_id).unwrap().kind
+                        {
                             // This is a reference to a previously declared type.  If we look
                             // through it we should(?) get something that looks like a declaration,
                             // which we can mark as wanted.
-                            let decl_id = self.c_types[&decl_type_id]
+                            let decl_id = self
+                                .c_types
+                                .get(&decl_type_id)
+                                .unwrap()
                                 .kind
                                 .as_decl_or_typedef()
                                 .expect("target of CTypeKind::Elaborated isn't a decl?");
@@ -1388,7 +1393,7 @@ impl Index<CTypeId> for TypedAstContext {
     fn index(&self, index: CTypeId) -> &CType {
         match self.c_types.get(&index) {
             None => panic!("Could not find {:?} in TypedAstContext", index),
-            Some(ty) => ty,
+            Some(ty) => Box::leak(Box::new(ty.clone())),
         }
     }
 }

c2rust-transpile/src/c_ast/mod.rs

@@ -697,10 +697,10 @@ impl<W: Write> Printer<W> {
         let ty = context
             .c_types
             .get(&type_id)
-            .map(|l| &l.kind)
+            .map(|l| l.kind.clone())
             .unwrap_or_else(|| panic!("Could not find type with ID {:?}", type_id));
         use CTypeKind::*;
-        match ty {
+        match &ty {
             Pointer(ref qual_ty) => {
                 self.print_qtype(*qual_ty, None, context)?;
                 self.writer.write_all(b"*")?;