From e1a0584936b3aa5ce971e875dec750d2ae937d2e Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Wed, 31 Mar 2021 12:51:11 -0600
Subject: massively upgrade error handling

---
 src/makefile/macro.rs | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

(limited to 'src/makefile/macro.rs')

diff --git a/src/makefile/macro.rs b/src/makefile/macro.rs
index 79df339..88397c5 100644
--- a/src/makefile/macro.rs
+++ b/src/makefile/macro.rs
@@ -2,6 +2,7 @@ use std::collections::HashMap;
 use std::env;
 use std::fmt;
 
+use anyhow::Context;
 use regex::Regex;
 
 use super::functions;
@@ -15,9 +16,9 @@ pub(crate) enum MacroSource {
     Builtin,
 }
 
-pub(crate) trait LookupInternal: for<'a> Fn(&'a str) -> String {}
+pub(crate) trait LookupInternal: for<'a> Fn(&'a str) -> anyhow::Result<String> {}
 
-impl<F: for<'a> Fn(&'a str) -> String> LookupInternal for F {}
+impl<F: for<'a> Fn(&'a str) -> anyhow::Result<String>> LookupInternal for F {}
 
 #[derive(Clone)]
 pub(crate) struct MacroSet<'parent, 'lookup> {
@@ -50,13 +51,13 @@ impl<'parent, 'lookup> MacroSet<'parent, 'lookup> {
         }
     }
 
-    fn lookup_internal(&self, name: &str) -> String {
+    fn lookup_internal(&self, name: &str) -> anyhow::Result<String> {
         if let Some(lookup) = self.lookup_internal {
             lookup(name)
         } else if let Some(parent) = self.parent {
             parent.lookup_internal(name)
         } else {
-            panic!("no lookup possible");
+            anyhow::bail!("no lookup possible")
         }
     }
 
@@ -79,7 +80,7 @@ impl<'parent, 'lookup> MacroSet<'parent, 'lookup> {
         self.data.remove(name)
     }
 
-    pub(crate) fn expand(&self, text: &TokenString) -> String {
+    pub(crate) fn expand(&self, text: &TokenString) -> anyhow::Result<String> {
         let mut result = String::new();
         for token in text.tokens() {
             match token {
@@ -92,18 +93,20 @@ impl<'parent, 'lookup> MacroSet<'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)?
                     } else {
-                        self.get(name)
-                            .map_or_else(String::new, |(_, macro_value)| self.expand(macro_value))
+                        self.get(name).map_or_else(
+                            || Ok(String::new()),
+                            |(_, macro_value)| self.expand(macro_value),
+                        )?
                     };
                     let macro_value = match replacement {
                         Some((subst1, subst2)) => {
-                            let subst1 = self.expand(subst1);
+                            let subst1 = self.expand(subst1)?;
                             let subst1_suffix = regex::escape(&subst1);
-                            let subst1_suffix =
-                                Regex::new(&format!(r"{}\b", subst1_suffix)).unwrap();
-                            let subst2 = self.expand(subst2);
+                            let subst1_suffix = Regex::new(&format!(r"{}\b", subst1_suffix))
+                                .context("formed invalid regex somehow")?;
+                            let subst2 = self.expand(subst2)?;
                             subst1_suffix.replace_all(&macro_value, subst2).to_string()
                         }
                         None => macro_value,
@@ -111,11 +114,11 @@ impl<'parent, 'lookup> MacroSet<'parent, 'lookup> {
                     result.push_str(&macro_value);
                 }
                 Token::FunctionCall { name, args } => {
-                    result.push_str(&functions::expand_call(name, args, self));
+                    result.push_str(&functions::expand_call(name, args, self)?);
                 }
             }
         }
-        result
+        Ok(result)
     }
 
     pub(crate) fn with_lookup<'l, 's: 'l>(
-- 
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