From 605a205008168b3fff4cc5678184e68514ee206b Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Tue, 14 Apr 2020 21:27:48 -0500
Subject: [PATCH] Range errors for `slice`-likes include negatives.

Makes for less confusing errors when calling something
like `(slice [] 0 -10)`.
---
 CHANGELOG.md    |  1 +
 src/core/capi.c | 18 ++++++++++--------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 597a4451..5baeaa38 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 All notable changes to this project will be documented in this file.
 
 ## Unreleased - ???
+- Add `sh-rule` and `sh-phony` to jpm's dialect of Janet.
 - Change C api's `janet_formatb` -> `janet_formatbv`.
 - Add C `janet_formatb` to C api.
 - Add `edefer` macro to core.
diff --git a/src/core/capi.c b/src/core/capi.c
index ce7ef70b..797642c5 100644
--- a/src/core/capi.c
+++ b/src/core/capi.c
@@ -235,18 +235,20 @@ size_t janet_getsize(const Janet *argv, int32_t n) {
 
 int32_t janet_gethalfrange(const Janet *argv, int32_t n, int32_t length, const char *which) {
     int32_t raw = janet_getinteger(argv, n);
-    if (raw < 0) raw += length + 1;
-    if (raw < 0 || raw > length)
-        janet_panicf("%s index %d out of range [0,%d]", which, raw, length);
-    return raw;
+    int32_t not_raw = raw;
+    if (not_raw < 0) not_raw += length + 1;
+    if (not_raw < 0 || not_raw > length)
+        janet_panicf("%s index %d out of range [%d,%d]", which, raw, -length - 1, length);
+    return not_raw;
 }
 
 int32_t janet_getargindex(const Janet *argv, int32_t n, int32_t length, const char *which) {
     int32_t raw = janet_getinteger(argv, n);
-    if (raw < 0) raw += length;
-    if (raw < 0 || raw > length)
-        janet_panicf("%s index %d out of range [0,%d)", which, raw, length);
-    return raw;
+    int32_t not_raw = raw;
+    if (not_raw < 0) not_raw += length;
+    if (not_raw < 0 || not_raw > length)
+        janet_panicf("%s index %d out of range [%d,%d)", which, raw, -length, length);
+    return not_raw;
 }
 
 JanetView janet_getindexed(const Janet *argv, int32_t n) {