Test negative indices on Bash 4.2 and above.

src/tests/validity/array_get_negative_index_by_copy.ab

@@ -0,0 +1,30 @@
+// Output
+// Value at -5: ""
+// Value at -4: "zero"
+// Value at -3: "one"
+// Value at -2: "two"
+// Value at -1: "three"
+
+// Replace this with builtin if/when we get around to writing one.
+#[allow_absurd_cast]
+fun bash_version(): Num {
+    let major = trust $ echo "\$\{BASH_VERSINFO[0]}" $ as Num
+    let minor = trust $ echo "\$\{BASH_VERSINFO[1]}" $ as Num
+    return (major * 100) + minor
+}
+
+fun test_index(array) {
+    for index in -5..=-1 {
+        echo "Value at {index}: \"{array[index]}\""
+    }
+}
+
+main {
+    if bash_version() >= 402 {
+        let array = ["zero", "one", "two", "three"]
+        test_index(array)
+    } else {
+        // Negative indexing is not supported before Bash 4.
+        echo "Succeeded"
+    }
+}

src/tests/validity/array_get_negative_index_by_ref.ab

@@ -0,0 +1,30 @@
+// Output
+// Value at -5: ""
+// Value at -4: "zero"
+// Value at -3: "one"
+// Value at -2: "two"
+// Value at -1: "three"
+
+// Replace this with builtin if/when we get around to writing one.
+#[allow_absurd_cast]
+fun bash_version(): Num {
+    let major = trust $ echo "\$\{BASH_VERSINFO[0]}" $ as Num
+    let minor = trust $ echo "\$\{BASH_VERSINFO[1]}" $ as Num
+    return (major * 100) + minor
+}
+
+fun test_index(ref byref) {
+    for index in -5..=-1 {
+        echo "Value at {index}: \"{byref[index]}\""
+    }
+}
+
+main {
+    if bash_version() >= 402 {
+        let array = ["zero", "one", "two", "three"]
+        test_index(array)
+    } else {
+        // Negative indexing is not supported before Bash 4.
+        echo "Succeeded"
+    }
+}

src/tests/validity/array_get_negative_index_local.ab

@@ -0,0 +1,29 @@
+// Output
+// Value at -5: ""
+// Value at -4: "zero"
+// Value at -3: "one"
+// Value at -2: "two"
+// Value at -1: "three"
+
+// Replace this with builtin if/when we get around to writing one.
+#[allow_absurd_cast]
+fun bash_version(): Num {
+    let major = trust $ echo "\$\{BASH_VERSINFO[0]}" $ as Num
+    let minor = trust $ echo "\$\{BASH_VERSINFO[1]}" $ as Num
+    return (major * 100) + minor
+}
+
+main {
+    if bash_version() >= 402 {
+        // Do not use loop; we want to test compile time arithmetic.
+        let array = ["zero", "one", "two", "three"]
+        echo "Value at -5: \"{array[-5]}\""
+        echo "Value at -4: \"{array[-4]}\""
+        echo "Value at -3: \"{array[-3]}\""
+        echo "Value at -2: \"{array[-2]}\""
+        echo "Value at -1: \"{array[-1]}\""
+    } else {
+        // Negative indexing is not supported before Bash 4.
+        echo "Succeeded"
+    }
+}

src/tests/validity/array_get_index_by_copy.ab → src/tests/validity/array_get_positive_index_by_copy.ab

@@ -1,17 +1,12 @@
 // Output
-// Value at -5: ""
-// Value at -4: "zero"
-// Value at -3: "one"
-// Value at -2: "two"
-// Value at -1: "three"
 // Value at 0: "zero"
 // Value at 1: "one"
 // Value at 2: "two"
 // Value at 3: "three"
 // Value at 4: ""
 
 fun test_index(array) {
-    for index in -5..=4 {
+    for index in 0..=4 {
         echo "Value at {index}: \"{array[index]}\""
     }
 }

src/tests/validity/array_get_index_by_ref.ab → src/tests/validity/array_get_positive_index_by_ref.ab

@@ -1,17 +1,12 @@
 // Output
-// Value at -5: ""
-// Value at -4: "zero"
-// Value at -3: "one"
-// Value at -2: "two"
-// Value at -1: "three"
 // Value at 0: "zero"
 // Value at 1: "one"
 // Value at 2: "two"
 // Value at 3: "three"
 // Value at 4: ""
 
 fun test_index(ref byref) {
-    for index in -5..=4 {
+    for index in 0..=4 {
         echo "Value at {index}: \"{byref[index]}\""
     }
 }

src/tests/validity/array_get_index_local.ab → src/tests/validity/array_get_positive_index_local.ab

@@ -1,9 +1,4 @@
 // Output
-// Value at -5: ""
-// Value at -4: "zero"
-// Value at -3: "one"
-// Value at -2: "two"
-// Value at -1: "three"
 // Value at 0: "zero"
 // Value at 1: "one"
 // Value at 2: "two"
@@ -13,11 +8,6 @@
 main {
     // Do not use loop; we want to test compile time arithmetic.
     let array = ["zero", "one", "two", "three"]
-    echo "Value at -5: \"{array[-5]}\""
-    echo "Value at -4: \"{array[-4]}\""
-    echo "Value at -3: \"{array[-3]}\""
-    echo "Value at -2: \"{array[-2]}\""
-    echo "Value at -1: \"{array[-1]}\""
     echo "Value at 0: \"{array[0]}\""
     echo "Value at 1: \"{array[1]}\""
     echo "Value at 2: \"{array[2]}\""