From f2bb81496304981ac208ad664597172e532b17d5 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Wed, 7 Apr 2021 13:27:37 -0600
Subject: let macros in dependencies use $@ to get targets

---
 src/makefile/input.rs | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/src/makefile/input.rs b/src/makefile/input.rs
index 460a8a0..beb517a 100644
--- a/src/makefile/input.rs
+++ b/src/makefile/input.rs
@@ -497,7 +497,42 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
             log::error!("rule-specific macros are not implemented yet");
             return Ok(());
         }
-        let prerequisites = self.expand_macros(&prerequisites)?;
+        let prerequisites = self
+            .macros
+            .with_lookup(&|macro_name: &str| {
+                let macro_pieces = if macro_name.starts_with('@') {
+                    // The $@ shall evaluate to the full target name of the
+                    // current target.
+                    targets.iter()
+                } else {
+                    bail!("unknown internal macro")
+                };
+
+                let macro_pieces = if macro_name.ends_with('D') {
+                    macro_pieces
+                        .map(|x| {
+                            Path::new(x)
+                                .parent()
+                                .ok_or_else(|| eyre!("no parent"))
+                                .map(|x| x.to_string_lossy().into())
+                        })
+                        .collect::<Result<Vec<String>, _>>()?
+                } else if macro_name.ends_with('F') {
+                    macro_pieces
+                        .map(|x| {
+                            Path::new(x)
+                                .file_name()
+                                .ok_or_else(|| eyre!("no filename"))
+                                .map(|x| x.to_string_lossy().into())
+                        })
+                        .collect::<Result<Vec<String>, _>>()?
+                } else {
+                    macro_pieces.map(|&x| x.to_owned()).collect::<Vec<String>>()
+                };
+
+                Ok(macro_pieces.join(" "))
+            })
+            .expand(&prerequisites)?;
         let prerequisites = prerequisites
             .split_whitespace()
             .map(|x| x.into())
-- 
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