From b9ed20a76daff530bfc84fe2e3bb34a5a51ef61f Mon Sep 17 00:00:00 2001
From: gluaxspeed <jonathan.t.pavlik@gmail.com>
Date: Mon, 19 Jul 2021 11:17:10 -0700
Subject: [PATCH 1/2] use the array range access span for errors if the side is
 none

---
 asg/src/expression/array_range_access.rs | 46 +++++++++++++-----------
 1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/asg/src/expression/array_range_access.rs b/asg/src/expression/array_range_access.rs
index 773e8c66a9..c0810a2586 100644
--- a/asg/src/expression/array_range_access.rs
+++ b/asg/src/expression/array_range_access.rs
@@ -148,24 +148,28 @@ impl<'a> FromAst<'a, leo_ast::ArrayRangeAccessExpression> for ArrayRangeAccessEx
             _ => None,
         };
         let const_right = match right.map(|x| x.const_value()) {
-            Some(Some(ConstValue::Int(value))) => {
-                let value = value.to_usize();
-                if let Some(value) = value {
-                    if value > parent_size {
-                        return Err(AsgConvertError::array_index_out_of_bounds(
-                            value,
-                            &right.unwrap().span().cloned().unwrap_or_default(),
-                        ));
+            Some(Some(ConstValue::Int(inner_value))) => {
+                let usize_value = inner_value.to_usize();
+                if let Some(inner_value) = usize_value {
+                    if inner_value > parent_size {
+                        let error_span = if let Some(right) = right {
+                            right.span().cloned().unwrap_or_default()
+                        } else {
+                            value.span.clone()
+                        };
+                        return Err(AsgConvertError::array_index_out_of_bounds(inner_value, &error_span));
                     } else if let Some(left) = const_left {
-                        if left > value {
-                            return Err(AsgConvertError::array_index_out_of_bounds(
-                                value,
-                                &right.unwrap().span().cloned().unwrap_or_default(),
-                            ));
+                        if left > inner_value {
+                            let error_span = if let Some(right) = right {
+                                right.span().cloned().unwrap_or_default()
+                            } else {
+                                value.span.clone()
+                            };
+                            return Err(AsgConvertError::array_index_out_of_bounds(inner_value, &error_span));
                         }
                     }
                 }
-                value
+                usize_value
             }
             None => Some(parent_size),
             _ => None,
@@ -188,12 +192,14 @@ impl<'a> FromAst<'a, leo_ast::ArrayRangeAccessExpression> for ArrayRangeAccessEx
                     ));
                 }
             }
-            if let Some(value) = const_left {
-                if value + expected_len > parent_size {
-                    return Err(AsgConvertError::array_index_out_of_bounds(
-                        value,
-                        &left.unwrap().span().cloned().unwrap_or_default(),
-                    ));
+            if let Some(left_value) = const_left {
+                if left_value + expected_len > parent_size {
+                    let error_span = if let Some(left) = left {
+                        left.span().cloned().unwrap_or_default()
+                    } else {
+                        value.span.clone()
+                    };
+                    return Err(AsgConvertError::array_index_out_of_bounds(left_value, &error_span));
                 }
             }
             length = Some(expected_len);

From a2577231fd2d41a8b8c0e9dce4dc98c8e95a021c Mon Sep 17 00:00:00 2001
From: gluaxspeed <jonathan.t.pavlik@gmail.com>
Date: Mon, 19 Jul 2021 11:33:18 -0700
Subject: [PATCH 2/2] add test

---
 tests/compiler/array/array_range_access_fail.leo     | 12 ++++++++++++
 .../compiler/array/input/array_range_access_fail.in  |  2 ++
 .../compiler/array/array_range_access_fail.leo.out   |  5 +++++
 3 files changed, 19 insertions(+)
 create mode 100644 tests/compiler/array/array_range_access_fail.leo
 create mode 100644 tests/compiler/array/input/array_range_access_fail.in
 create mode 100644 tests/expectations/compiler/compiler/array/array_range_access_fail.leo.out

diff --git a/tests/compiler/array/array_range_access_fail.leo b/tests/compiler/array/array_range_access_fail.leo
new file mode 100644
index 0000000000..a73127b571
--- /dev/null
+++ b/tests/compiler/array/array_range_access_fail.leo
@@ -0,0 +1,12 @@
+/*
+namespace: Compile
+expectation: Fail
+input_file: input/array_range_access_fail.in
+*/
+
+function main (
+    const x: u32
+) {
+    const y = [1u8; 3];
+    const z: [u8; 2] = y[..1u32][..x];
+}
\ No newline at end of file
diff --git a/tests/compiler/array/input/array_range_access_fail.in b/tests/compiler/array/input/array_range_access_fail.in
new file mode 100644
index 0000000000..5bea7d78d8
--- /dev/null
+++ b/tests/compiler/array/input/array_range_access_fail.in
@@ -0,0 +1,2 @@
+[constants]
+x: u32 = 1u32;
\ No newline at end of file
diff --git a/tests/expectations/compiler/compiler/array/array_range_access_fail.leo.out b/tests/expectations/compiler/compiler/array/array_range_access_fail.leo.out
new file mode 100644
index 0000000000..4fa4f71894
--- /dev/null
+++ b/tests/expectations/compiler/compiler/array/array_range_access_fail.leo.out
@@ -0,0 +1,5 @@
+---
+namespace: Compile
+expectation: Fail
+outputs:
+  - "    --> compiler-test:7:24\n     |\n   7 |     const z: [u8; 2] = y[..1u32][..x];\n     |                        ^^^^^^^^^^^^^^\n     |\n     = array index out of bounds: '0'"