Stabilize Span::file and Span::local_file

Author: dtolnay

build.rs

@@ -20,6 +20,7 @@ fn main() {
         println!("cargo:rustc-check-cfg=cfg(no_literal_c_string)");
         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)");
@@ -128,6 +129,12 @@ 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/fallback.rs

@@ -23,7 +23,7 @@ use core::str::FromStr;
 use std::ffi::CStr;
 #[cfg(wrap_proc_macro)]
 use std::panic;
-#[cfg(procmacro2_semver_exempt)]
+#[cfg(span_locations)]
 use std::path::PathBuf;
 
 /// Force use of proc-macro2's fallback implementation of the API for now, even
@@ -455,7 +455,6 @@ impl SourceMap {
         span
     }
 
-    #[cfg(procmacro2_semver_exempt)]
     fn filepath(&self, span: Span) -> String {
         for (i, file) in self.files.iter().enumerate() {
             if file.span_within(span) {
@@ -568,7 +567,7 @@ impl Span {
         })
     }
 
-    #[cfg(procmacro2_semver_exempt)]
+    #[cfg(span_locations)]
     pub(crate) fn file(&self) -> String {
         #[cfg(fuzzing)]
         return "<unspecified>".to_owned();
@@ -580,7 +579,7 @@ impl Span {
         })
     }
 
-    #[cfg(procmacro2_semver_exempt)]
+    #[cfg(span_locations)]
     pub(crate) fn local_file(&self) -> Option<PathBuf> {
         None
     }

src/lib.rs

@@ -174,7 +174,7 @@ use core::ops::RangeBounds;
 use core::str::FromStr;
 use std::error::Error;
 use std::ffi::CStr;
-#[cfg(procmacro2_semver_exempt)]
+#[cfg(span_locations)]
 use std::path::PathBuf;
 
 #[cfg(span_locations)]
@@ -471,10 +471,8 @@ impl Span {
     ///
     /// This might not correspond to a valid file system path. It might be
     /// remapped, or might be an artificial path such as `"<macro expansion>"`.
-    ///
-    /// This method is semver exempt and not exposed by default.
-    #[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
-    #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
+    #[cfg(span_locations)]
+    #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
     pub fn file(&self) -> String {
         self.inner.file()
     }
@@ -485,10 +483,8 @@ impl Span {
     ///
     /// This path should not be embedded in the output of the macro; prefer
     /// `file()` instead.
-    ///
-    /// This method is semver exempt and not exposed by default.
-    #[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
-    #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
+    #[cfg(span_locations)]
+    #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
     pub fn local_file(&self) -> Option<PathBuf> {
         self.inner.local_file()
     }

src/probe.rs

@@ -3,5 +3,8 @@
 #[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

@@ -8,6 +8,7 @@ extern crate proc_macro;
 
 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()
@@ -29,6 +30,14 @@ 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/probe/proc_macro_span_file.rs

@@ -0,0 +1,14 @@
+// The subset of Span's API stabilized in Rust 1.88.
+
+extern crate proc_macro;
+
+use proc_macro::Span;
+use std::path::PathBuf;
+
+pub fn file(this: &Span) -> String {
+    this.file()
+}
+
+pub fn local_file(this: &Span) -> Option<PathBuf> {
+    this.local_file()
+}

src/wrapper.rs

@@ -4,6 +4,8 @@ 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};
@@ -12,7 +14,7 @@ use core::fmt::{self, Debug, Display};
 use core::ops::Range;
 use core::ops::RangeBounds;
 use std::ffi::CStr;
-#[cfg(super_unstable)]
+#[cfg(span_locations)]
 use std::path::PathBuf;
 
 #[derive(Clone)]
@@ -463,18 +465,24 @@ impl Span {
         }
     }
 
-    #[cfg(super_unstable)]
+    #[cfg(span_locations)]
     pub(crate) fn file(&self) -> String {
         match self {
-            Span::Compiler(s) => s.file(),
+            #[cfg(proc_macro_span_file)]
+            Span::Compiler(s) => proc_macro_span_file::file(s),
+            #[cfg(not(proc_macro_span_file))]
+            Span::Compiler(_) => "<token stream>".to_owned(),
             Span::Fallback(s) => s.file(),
         }
     }
 
-    #[cfg(super_unstable)]
+    #[cfg(span_locations)]
     pub(crate) fn local_file(&self) -> Option<PathBuf> {
         match self {
-            Span::Compiler(s) => s.local_file(),
+            #[cfg(proc_macro_span_file)]
+            Span::Compiler(s) => proc_macro_span_file::local_file(s),
+            #[cfg(not(proc_macro_span_file))]
+            Span::Compiler(_) => None,
             Span::Fallback(s) => s.local_file(),
         }
     }