Drop probe for proc_macro_span_file feature

build.rs

@@ -19,9 +19,9 @@ fn main() {
         println!("cargo:rustc-check-cfg=cfg(no_is_available)");
         println!("cargo:rustc-check-cfg=cfg(no_literal_byte_character)");
         println!("cargo:rustc-check-cfg=cfg(no_literal_c_string)");
+        println!("cargo:rustc-check-cfg=cfg(no_proc_macro_span_file)");
         println!("cargo:rustc-check-cfg=cfg(no_source_text)");
         println!("cargo:rustc-check-cfg=cfg(proc_macro_span)");
-        println!("cargo:rustc-check-cfg=cfg(proc_macro_span_file)");
         println!("cargo:rustc-check-cfg=cfg(proc_macro_span_location)");
         println!("cargo:rustc-check-cfg=cfg(procmacro2_backtrace)");
         println!("cargo:rustc-check-cfg=cfg(procmacro2_build_probe)");
@@ -66,6 +66,12 @@ fn main() {
         println!("cargo:rustc-cfg=no_literal_c_string");
     }
 
+    if rustc < 88 {
+        // Do not call libproc_macro's Span::file and Span::local_file. Always
+        // return dummy values.
+        println!("cargo:rustc-cfg=no_proc_macro_span_file");
+    }
+
     if !cfg!(feature = "proc-macro") {
         println!("cargo:rerun-if-changed=build.rs");
         return;
@@ -130,12 +136,6 @@ fn main() {
         println!("cargo:rustc-cfg=proc_macro_span_location");
     }
 
-    if proc_macro_span || (rustc >= 88 && compile_probe_stable("proc_macro_span_file")) {
-        // Enable non-dummy behavior of Span::file and Span::local_file methods
-        // on Rust 1.88+.
-        println!("cargo:rustc-cfg=proc_macro_span_file");
-    }
-
     if semver_exempt && proc_macro_span {
         // Implement the semver exempt API in terms of the nightly-only
         // proc_macro API.

src/probe.rs

@@ -3,8 +3,5 @@
 #[cfg(proc_macro_span)]
 pub(crate) mod proc_macro_span;
 
-#[cfg(proc_macro_span_file)]
-pub(crate) mod proc_macro_span_file;
-
 #[cfg(proc_macro_span_location)]
 pub(crate) mod proc_macro_span_location;

src/probe/proc_macro_span.rs

@@ -9,10 +9,8 @@ extern crate alloc;
 extern crate proc_macro;
 extern crate std;
 
-use alloc::string::String;
 use core::ops::{Range, RangeBounds};
 use proc_macro::{Literal, Span};
-use std::path::PathBuf;
 
 pub fn byte_range(this: &Span) -> Range<usize> {
     this.byte_range()
@@ -34,14 +32,6 @@ pub fn column(this: &Span) -> usize {
     this.column()
 }
 
-pub fn file(this: &Span) -> String {
-    this.file()
-}
-
-pub fn local_file(this: &Span) -> Option<PathBuf> {
-    this.local_file()
-}
-
 pub fn join(this: &Span, other: Span) -> Option<Span> {
     this.join(other)
 }

src/wrapper.rs

@@ -4,12 +4,10 @@ use crate::fallback::{self, FromStr2 as _};
 use crate::location::LineColumn;
 #[cfg(proc_macro_span)]
 use crate::probe::proc_macro_span;
-#[cfg(all(span_locations, proc_macro_span_file))]
-use crate::probe::proc_macro_span_file;
 #[cfg(all(span_locations, proc_macro_span_location))]
 use crate::probe::proc_macro_span_location;
 use crate::{Delimiter, Punct, Spacing, TokenTree};
-#[cfg(all(span_locations, not(proc_macro_span_file)))]
+#[cfg(all(span_locations, no_proc_macro_span_file))]
 use alloc::borrow::ToOwned as _;
 use alloc::string::{String, ToString as _};
 use alloc::vec::Vec;
@@ -472,9 +470,9 @@ impl Span {
     #[cfg(span_locations)]
     pub(crate) fn file(&self) -> String {
         match self {
-            #[cfg(proc_macro_span_file)]
-            Span::Compiler(s) => proc_macro_span_file::file(s),
-            #[cfg(not(proc_macro_span_file))]
+            #[cfg(not(no_proc_macro_span_file))]
+            Span::Compiler(s) => s.file(),
+            #[cfg(no_proc_macro_span_file)]
             Span::Compiler(_) => "<token stream>".to_owned(),
             Span::Fallback(s) => s.file(),
         }
@@ -483,9 +481,9 @@ impl Span {
     #[cfg(span_locations)]
     pub(crate) fn local_file(&self) -> Option<PathBuf> {
         match self {
-            #[cfg(proc_macro_span_file)]
-            Span::Compiler(s) => proc_macro_span_file::local_file(s),
-            #[cfg(not(proc_macro_span_file))]
+            #[cfg(not(no_proc_macro_span_file))]
+            Span::Compiler(s) => s.local_file(),
+            #[cfg(no_proc_macro_span_file)]
             Span::Compiler(_) => None,
             Span::Fallback(s) => s.local_file(),
         }