proc_macro: Increase FFIString usage

Two remaining structures in the rust interface were still using raw
string pointer and length couples to communicate with the C++ library
throught extern C functions. Using FFIString instead allow us to reduce
the scope of potential errors using those raw pointers. As FFIString
encapsulate raw pointer operations there will be only one locaiton to
look after.

ChangeLog:

	* libgrust/libproc_macro/rust/bridge/literal.rs: Change extern C
	function argument from raw string pointer and length to
	FFIString.
	* libgrust/libproc_macro/rust/bridge/token_stream.rs: Likewise.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

2 files changed, 5 insertions, 20 deletions

diff --git a/libgrust/libproc_macro/rust/bridge/literal.rs b/libgrust/libproc_macro/rust/bridge/literal.rs
index b03e363..5982504 100644
--- a/libgrust/libproc_macro/rust/bridge/literal.rs
+++ b/libgrust/libproc_macro/rust/bridge/literal.rs
@@ -1,12 +1,10 @@
 use bridge::{ffistring::FFIString, span::Span};
-use std::convert::TryInto;
-use std::ffi::c_uchar;
 use std::fmt;
 use std::str::FromStr;
 use LexError;
 
 extern "C" {
-    fn Literal__from_string(str: *const c_uchar, len: u64, lit: *mut Literal) -> bool;
+    fn Literal__from_string(str: FFIString, lit: *mut Literal) -> bool;
 }
 
 #[repr(C)]
@@ -234,13 +232,7 @@ impl FromStr for Literal {
         };
         // TODO: We might want to pass a LexError by reference to retrieve
         // error information
-        if unsafe {
-            Literal__from_string(
-                string.as_ptr(),
-                string.len().try_into().unwrap(),
-                &mut lit as *mut Literal,
-            )
-        } {
+        if unsafe { Literal__from_string(string.into(), &mut lit as *mut Literal) } {
             Err(LexError)
         } else {
             Ok(lit)
diff --git a/libgrust/libproc_macro/rust/bridge/token_stream.rs b/libgrust/libproc_macro/rust/bridge/token_stream.rs
index 79f161f..094f91f 100644
--- a/libgrust/libproc_macro/rust/bridge/token_stream.rs
+++ b/libgrust/libproc_macro/rust/bridge/token_stream.rs
@@ -1,6 +1,5 @@
-use bridge::{group::Group, ident::Ident, literal::Literal, punct::Punct};
+use bridge::{ffistring::FFIString, group::Group, ident::Ident, literal::Literal, punct::Punct};
 use std::convert::TryInto;
-use std::ffi::c_uchar;
 use std::fmt;
 use std::slice;
 use std::str::FromStr;
@@ -13,7 +12,7 @@ extern "C" {
     fn TokenStream__new() -> TokenStream;
     fn TokenStream__with_capacity(capacity: u64) -> TokenStream;
     fn TokenStream__push(stream: *mut TokenStream, tree: TokenTree);
-    fn TokenStream__from_string(str: *const c_uchar, len: u64, ts: *mut TokenStream) -> bool;
+    fn TokenStream__from_string(str: FFIString, ts: *mut TokenStream) -> bool;
     fn TokenStream__clone(ts: *const TokenStream) -> TokenStream;
     fn TokenStream__drop(stream: *mut TokenStream);
 }
@@ -136,13 +135,7 @@ impl FromStr for TokenStream {
     type Err = LexError;
     fn from_str(string: &str) -> Result<Self, LexError> {
         let mut ts = TokenStream::new();
-        if unsafe {
-            TokenStream__from_string(
-                string.as_ptr(),
-                string.len().try_into().unwrap(),
-                &mut ts as *mut TokenStream,
-            )
-        } {
+        if unsafe { TokenStream__from_string(string.into(), &mut ts as *mut TokenStream) } {
             Err(LexError)
         } else {
             Ok(ts)