make source_text take non mutable reference of self

Author: Shourya742

crates/proc-macro-srv-cli/src/main_loop.rs

@@ -175,7 +175,7 @@ struct ProcMacroClientHandle {
 }
 
 impl proc_macro_srv::ProcMacroClientInterface for ProcMacroClientHandle {
-    fn source_text(&mut self, file_id: u32, start: u32, end: u32) -> Option<String> {
+    fn source_text(&self, file_id: u32, start: u32, end: u32) -> Option<String> {
         self.subreq_tx.send(bidirectional::SubRequest::SourceText { file_id, start, end }).ok()?;
 
         match self.subresp_rx.recv().ok()? {

crates/proc-macro-srv/src/lib.rs

@@ -94,7 +94,7 @@ impl<'env> ProcMacroSrv<'env> {
 pub type ProcMacroClientHandle = Box<dyn ProcMacroClientInterface + Send>;
 
 pub trait ProcMacroClientInterface {
-    fn source_text(&mut self, file_id: u32, start: u32, end: u32) -> Option<String>;
+    fn source_text(&self, file_id: u32, start: u32, end: u32) -> Option<String>;
 }
 
 const EXPANDER_STACK_SIZE: usize = 8 * 1024 * 1024;

crates/proc-macro-srv/src/server_impl/rust_analyzer_span.rs

@@ -156,7 +156,7 @@ impl server::Span for RaSpanServer {
         let start: u32 = span.range.start().into();
         let end: u32 = span.range.end().into();
 
-        self.callback.as_mut()?.source_text(file_id.file_id().index(), start, end)
+        self.callback.as_ref()?.source_text(file_id.file_id().index(), start, end)
     }
 
     fn parent(&mut self, _span: Self::Span) -> Option<Self::Span> {