From ab249a1f95e898b2d81e480b32a5b6ad9e4a7087 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Sun, 11 Apr 2021 18:40:46 -0600
Subject: add more error context

---
 src/makefile/input.rs | 24 +++++++++++++++++++++---
 src/makefile/macro.rs | 12 +++++++++---
 2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/src/makefile/input.rs b/src/makefile/input.rs
index beb517a..e8e2e95 100644
--- a/src/makefile/input.rs
+++ b/src/makefile/input.rs
@@ -327,8 +327,24 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
             };
 
             match line_type {
-                LineType::Rule => self.read_rule(&line_tokens, line_number)?,
-                LineType::Macro => self.read_macro(line_tokens, line_number)?,
+                LineType::Rule => {
+                    self.read_rule(&line_tokens, line_number)
+                        .wrap_err_with(|| {
+                            format!(
+                                "while parsing rule definition starting on line {}",
+                                line_number
+                            )
+                        })?
+                }
+                LineType::Macro => {
+                    self.read_macro(line_tokens, line_number)
+                        .wrap_err_with(|| {
+                            format!(
+                                "while parsing macro definition starting on line {}",
+                                line_number
+                            )
+                        })?
+                }
                 LineType::Unknown => {
                     if !line_tokens.is_empty() {
                         // TODO handle assignments here
@@ -772,7 +788,9 @@ impl<'a, 'parent, R: BufRead> MakefileReader<'a, 'parent, R> {
     }
 
     fn expand_macros(&self, text: &TokenString) -> Result<String> {
-        self.macros.expand(text)
+        self.macros
+            .expand(text)
+            .wrap_err_with(|| format!("while expanding \"{}\"", text))
     }
 
     pub fn finish(self) -> FinishedMakefileReader {
diff --git a/src/makefile/macro.rs b/src/makefile/macro.rs
index f00fdff..3444e2c 100644
--- a/src/makefile/macro.rs
+++ b/src/makefile/macro.rs
@@ -218,7 +218,9 @@ impl<'parent, 'lookup> Set<'parent, 'lookup> {
             match token {
                 Token::Text(t) => result.push_str(t),
                 Token::MacroExpansion { name, replacement } => {
-                    let name = self.expand(name)?;
+                    let name = self
+                        .expand(name)
+                        .wrap_err_with(|| format!("while expanding \"{}\"", name))?;
                     let internal_macro_names = &['@', '?', '<', '*'][..];
                     let internal_macro_suffices = &['D', 'F'][..];
                     let just_internal = name.len() == 1 && name.starts_with(internal_macro_names);
@@ -226,14 +228,18 @@ impl<'parent, 'lookup> Set<'parent, 'lookup> {
                         && name.starts_with(internal_macro_names)
                         && name.ends_with(internal_macro_suffices);
                     let macro_value = if just_internal || suffixed_internal {
-                        self.lookup_internal(&name)?
+                        self.lookup_internal(&name)
+                            .wrap_err_with(|| format!("while expanding $\"{}\"", name))?
                     } else {
                         self.get(&name).map_or_else(
                             || {
                                 self.warn(format!("undefined macro {}", name));
                                 Ok(String::new())
                             },
-                            |x| self.expand(&x.text),
+                            |x| {
+                                self.expand(&x.text)
+                                    .wrap_err_with(|| format!("while expanding \"{}\"", &x.text))
+                            },
                         )?
                     };
                     let macro_value = match replacement {
-- 
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