From 050a3b166123be17c8dfdbd47e1b439040101884 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Sun, 4 Apr 2021 15:17:12 -0600
Subject: don't assume something's an inference rule unless it's on the suffix
 list

---
 src/makefile/input.rs | 39 +++++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/src/makefile/input.rs b/src/makefile/input.rs
index b02cdb6..5afecc6 100644
--- a/src/makefile/input.rs
+++ b/src/makefile/input.rs
@@ -63,10 +63,16 @@ impl LineType {
     }
 }
 
+#[derive(Debug)]
+struct InferenceMatch<'a> {
+    s1: &'a str,
+    s2: &'a str,
+}
+
 fn inference_match<'a>(
     targets: &[&'a str],
     prerequisites: &[String],
-) -> Option<regex::Captures<'a>> {
+) -> Option<InferenceMatch<'a>> {
     lazy_static! {
         static ref INFERENCE_RULE: Regex =
             Regex::new(r"^(?P<s2>(\.[^/.]+)?)(?P<s1>\.[^/.]+)$").unwrap();
@@ -81,7 +87,10 @@ fn inference_match<'a>(
         && inference_match.is_some()
         && special_target_match.is_none();
     if inference_rule {
-        inference_match
+        inference_match.map(|x| InferenceMatch {
+            s1: x.name("s1").unwrap().as_str(),
+            s2: x.name("s2").unwrap().as_str(),
+        })
     } else {
         None
     }
@@ -343,6 +352,15 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
         }
     }
 
+    fn special_target_has_prereq(&self, target: &str, name: &str) -> bool {
+        match self.targets.get(target) {
+            Some(target) => {
+                target.prerequisites.is_empty() || target.prerequisites.iter().any(|e| e == name)
+            }
+            None => false,
+        }
+    }
+
     fn read_rule(&mut self, line_tokens: &TokenString, line_number: usize) -> Result<()> {
         let (targets, not_targets) = line_tokens
             .split_once(':')
@@ -407,10 +425,23 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
             return Ok(());
         }
 
+        // don't interpret things like `.tmp: ; mkdir -p $@` as single-suffix rules
+        let inference_match = inference_match.and_then(|inference| {
+            if (inference.s1.is_empty()
+                || self.special_target_has_prereq(".SUFFIXES", inference.s1))
+                && (inference.s2.is_empty()
+                    || self.special_target_has_prereq(".SUFFIXES", inference.s2))
+            {
+                Some(inference)
+            } else {
+                None
+            }
+        });
+
         if let Some(inference_match) = inference_match {
             let new_rule = InferenceRule::new_suffix(
-                inference_match.name("s1").unwrap().as_str().to_owned(),
-                inference_match.name("s2").unwrap().as_str().to_owned(),
+                inference_match.s1.to_owned(),
+                inference_match.s2.to_owned(),
                 commands,
             );
             log::trace!(
-- 
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