Remove check for std::borrow::Cow optimization

Author: tiaanl

build.rs

@@ -42,9 +42,5 @@ fn main() {
         println!("cargo:rustc-cfg=rustc_has_pr45225")
     }
 
-    if std::mem::size_of::<std::borrow::Cow<'static, str>>() == 24 {
-        println!("cargo:rustc-cfg=rustc_has_better_cow_layout")
-    }
-
     codegen::main();
 }

src/size_of_tests.rs

@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use crate::cow_rc_str::CowRcStr;
 use crate::tokenizer::Token;
-use std::borrow::Cow;
 
 macro_rules! size_of_test {
     ($testname: ident, $t: ty, $expected_size: expr) => {
@@ -38,8 +36,6 @@ macro_rules! size_of_test {
 
 // Some of these assume 64-bit
 size_of_test!(token, Token, 32);
-size_of_test!(std_cow_str, Cow<'static, str>, if cfg!(rustc_has_better_cow_layout) { 24 } else { 32 });
-size_of_test!(cow_rc_str, CowRcStr, 16);
 
 size_of_test!(tokenizer, crate::tokenizer::Tokenizer, 72);
 size_of_test!(
@@ -51,14 +47,12 @@ size_of_test!(parser, crate::parser::Parser, 16);
 size_of_test!(source_position, crate::SourcePosition, 8);
 size_of_test!(parser_state, crate::ParserState, 24);
 
-size_of_test!(basic_parse_error, crate::BasicParseError, if cfg!(rustc_has_better_cow_layout) { 40 } else { 48 });
+size_of_test!(basic_parse_error, crate::BasicParseError, 40);
 size_of_test!(
     parse_error_lower_bound,
     crate::ParseError<()>,
-    if cfg!(rustc_has_better_cow_layout) {
+    if cfg!(rustc_has_pr45225) {
         40
-    } else if cfg!(rustc_has_pr45225) {
-        48
     } else {
         56
     }