constify immutable arguments in a few places; move decoded_input.h above loc.h in merge_headers script

Author: iliabylich

codegen/examples/merge_headers.rs

@@ -3,12 +3,12 @@ const HEADERS: &[&str] = &[
     "string.h",
     "bytes.h",
     "source_line.h",
+    "decoded_input.h",
     "loc.h",
     "token_ids.h",
     "token.h",
     "comment.h",
     "magic_comment.h",
-    "decoded_input.h",
     "nodes.h",
     "messages.h",
     "diagnostic.h",

diagnostic.h

@@ -42,8 +42,8 @@ typedef struct LIB_RUBY_PARSER_Diagnostic
     Return owned NULL-terminated string.
 */
 char *LIB_RUBY_PARSER_render_diagnostic(
-    LIB_RUBY_PARSER_Diagnostic *diagnostic,
-    LIB_RUBY_PARSER_DecodedInput *input);
+    const LIB_RUBY_PARSER_Diagnostic *diagnostic,
+    const LIB_RUBY_PARSER_DecodedInput *input);
 
 /*
     Diagnostic destructor.

ruby-parser-c/src/diagnostic.rs

@@ -42,8 +42,8 @@ pub extern "C" fn LIB_RUBY_PARSER_drop_diagnostic_list(diagnostic_list: *mut Vec
 
 #[no_mangle]
 pub extern "C" fn LIB_RUBY_PARSER_render_diagnostic(
-    diagnostic: *mut Diagnostic,
-    input: *mut DecodedInput,
+    diagnostic: *const Diagnostic,
+    input: *const DecodedInput,
 ) -> *mut i8 {
     let diagnostic = unsafe { diagnostic.as_ref().unwrap() };
     let input = unsafe { input.as_ref().unwrap() };

ruby-parser-c/src/token.rs

@@ -30,7 +30,7 @@ pub extern "C" fn lib_ruby_parser__test__make_token_eq(
 }
 
 #[no_mangle]
-pub extern "C" fn LIB_RUBY_PARSER_token_name(token: *mut Token) -> *mut i8 {
+pub extern "C" fn LIB_RUBY_PARSER_token_name(token: *const Token) -> *mut i8 {
     let token = unsafe { token.as_ref().unwrap() };
     let token_name = token.token_name();
     std::ffi::CString::new(token_name).unwrap().into_raw()

token.h

@@ -19,7 +19,7 @@ typedef struct LIB_RUBY_PARSER_Token
 /*
     Returns token name (like "kDEF") for a given token.
 */
-char *LIB_RUBY_PARSER_token_name(LIB_RUBY_PARSER_Token *token);
+char *LIB_RUBY_PARSER_token_name(const LIB_RUBY_PARSER_Token *token);
 /*
     Token destructor.
     Just like Rust/C++ destructor it performs cleanup of "embedded" resources.