From 67c6cbaf162f6244dbf4a87dc829975278590df9 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sat, 24 Sep 2022 15:20:56 -0700
Subject: [PATCH 1/2] Expose proc_macro's source_text() on Span

---
 build.rs        |  4 ++++
 src/fallback.rs | 19 +++++++++++++++++++
 src/lib.rs      | 11 +++++++++++
 src/wrapper.rs  | 10 ++++++++++
 4 files changed, 44 insertions(+)

diff --git a/build.rs b/build.rs
index b69d813f..59505a50 100644
--- a/build.rs
+++ b/build.rs
@@ -100,6 +100,10 @@ fn main() {
         println!("cargo:rustc-cfg=no_is_available");
     }
 
+    if version.minor < 66 {
+        println!("cargo:rustc-cfg=no_source_text");
+    }
+
     let target = env::var("TARGET").unwrap();
     if !enable_use_proc_macro(&target) {
         return;
diff --git a/src/fallback.rs b/src/fallback.rs
index fc3cd515..36064cef 100644
--- a/src/fallback.rs
+++ b/src/fallback.rs
@@ -342,6 +342,7 @@ thread_local! {
         files: vec![FileInfo {
             #[cfg(procmacro2_semver_exempt)]
             name: "<unspecified>".to_owned(),
+            source_text: String::new(),
             span: Span { lo: 0, hi: 0 },
             lines: vec![0],
         }],
@@ -352,6 +353,7 @@ thread_local! {
 struct FileInfo {
     #[cfg(procmacro2_semver_exempt)]
     name: String,
+    source_text: String,
     span: Span,
     lines: Vec<usize>,
 }
@@ -379,6 +381,12 @@ impl FileInfo {
     fn span_within(&self, span: Span) -> bool {
         span.lo >= self.span.lo && span.hi <= self.span.hi
     }
+
+    fn source_text(&self, span: Span) -> String {
+        let lo = (span.lo - self.span.lo) as usize;
+        let hi = (span.hi - self.span.lo) as usize;
+        self.source_text[lo..hi].to_owned()
+    }
 }
 
 /// Computes the offsets of each line in the given source string
@@ -425,6 +433,7 @@ impl SourceMap {
         self.files.push(FileInfo {
             #[cfg(procmacro2_semver_exempt)]
             name: name.to_owned(),
+            source_text: src.to_owned(),
             span,
             lines,
         });
@@ -554,6 +563,16 @@ impl Span {
         })
     }
 
+    #[cfg(not(span_locations))]
+    pub fn source_text(&self) -> Option<String> {
+        None
+    }
+
+    #[cfg(span_locations)]
+    pub fn source_text(&self) -> Option<String> {
+        SOURCE_MAP.with(|cm| Some(cm.borrow().fileinfo(*self).source_text(*self)))
+    }
+
     #[cfg(not(span_locations))]
     pub(crate) fn first_byte(self) -> Self {
         self
diff --git a/src/lib.rs b/src/lib.rs
index 4eb756bc..83e99ce4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -528,6 +528,17 @@ impl Span {
     pub fn eq(&self, other: &Span) -> bool {
         self.inner.eq(&other.inner)
     }
+
+    /// Returns the source text behind a span. This preserves the original
+    /// source code, including spaces and comments. It only returns a result if
+    /// the span corresponds to real source code.
+    ///
+    /// Note: The observable result of a macro should only rely on the tokens
+    /// and not on this source text. The result of this function is a best
+    /// effort to be used for diagnostics only.
+    pub fn source_text(&self) -> Option<String> {
+        self.inner.source_text()
+    }
 }
 
 /// Prints a span in a form convenient for debugging.
diff --git a/src/wrapper.rs b/src/wrapper.rs
index 720dcdd3..00f67cd6 100644
--- a/src/wrapper.rs
+++ b/src/wrapper.rs
@@ -530,6 +530,16 @@ impl Span {
         }
     }
 
+    pub fn source_text(&self) -> Option<String> {
+        match self {
+            #[cfg(not(no_source_text))]
+            Span::Compiler(s) => s.source_text(),
+            #[cfg(no_source_text)]
+            Span::Compiler(_) => None,
+            Span::Fallback(s) => s.source_text(),
+        }
+    }
+
     fn unwrap_nightly(self) -> proc_macro::Span {
         match self {
             Span::Compiler(s) => s,

From efeb5eceb10e7a0a501f7f3f43d7ba06c1d23d2a Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Tue, 21 Mar 2023 22:44:33 -0700
Subject: [PATCH 2/2] Call site has no source text

---
 src/fallback.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/fallback.rs b/src/fallback.rs
index 36064cef..b0ed7b06 100644
--- a/src/fallback.rs
+++ b/src/fallback.rs
@@ -570,7 +570,11 @@ impl Span {
 
     #[cfg(span_locations)]
     pub fn source_text(&self) -> Option<String> {
-        SOURCE_MAP.with(|cm| Some(cm.borrow().fileinfo(*self).source_text(*self)))
+        if self.is_call_site() {
+            None
+        } else {
+            Some(SOURCE_MAP.with(|cm| cm.borrow().fileinfo(*self).source_text(*self)))
+        }
     }
 
     #[cfg(not(span_locations))]
@@ -598,6 +602,11 @@ impl Span {
             hi: self.hi,
         }
     }
+
+    #[cfg(span_locations)]
+    fn is_call_site(&self) -> bool {
+        self.lo == 0 && self.hi == 0
+    }
 }
 
 impl Debug for Span {
@@ -613,7 +622,7 @@ impl Debug for Span {
 pub(crate) fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
     #[cfg(span_locations)]
     {
-        if span.lo == 0 && span.hi == 0 {
+        if span.is_call_site() {
             return;
         }
     }