From 20c824743e78ee529cb74bc9e0d255ce588e8690 Mon Sep 17 00:00:00 2001
From: Chris Pressey <cpressey@catseye.tc>
Date: Mon, 5 Feb 2018 12:35:19 +0000
Subject: [PATCH] Fix table access bug where index wasn't required to be
 initialized.

---
 HISTORY.md                   |  1 +
 src/sixtypical/analyzer.py   |  2 ++
 tests/SixtyPical Analysis.md | 43 ++++++++++++++++++++++++++++++++++--
 3 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/HISTORY.md b/HISTORY.md
index df6ec64..776ab73 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -8,6 +8,7 @@ History of SixtyPical
 *   Initialized `byte table` values need not have all 256 bytes initialized.
 *   Constraints for `vector` type come immediately after the type, not the variable.
 *   `vector table` storage, and ability to copy vectors in and out of same.
+*   Fixed bug where index register wasn't required to be initialized before table access.
 
 0.10
 ----
diff --git a/src/sixtypical/analyzer.py b/src/sixtypical/analyzer.py
index 2abc5b3..2320dbd 100644
--- a/src/sixtypical/analyzer.py
+++ b/src/sixtypical/analyzer.py
@@ -238,6 +238,7 @@ class Analyzer(object):
                     raise TypeMismatchError('%s and %s in %s' %
                         (src.name, dest.name, self.current_routine.name)
                     )
+                context.assert_meaningful(instr.index)
             elif src.type != dest.type:
                 raise TypeMismatchError('%s and %s in %s' %
                     (src.name, dest.name, self.current_routine.name)
@@ -250,6 +251,7 @@ class Analyzer(object):
                     pass
                 else:
                     raise TypeMismatchError((src, dest))
+                context.assert_meaningful(instr.index)
             elif src.type != dest.type:
                 raise TypeMismatchError('%s and %s in %s' %
                     (src.name, dest.name, self.current_routine.name)
diff --git a/tests/SixtyPical Analysis.md b/tests/SixtyPical Analysis.md
index 4f27f5e..51032b7 100644
--- a/tests/SixtyPical Analysis.md	
+++ b/tests/SixtyPical Analysis.md	
@@ -240,7 +240,7 @@ Can't `st` a `word` type.
 
 ### tables ###
 
-Storing to a table, you must use an index, and vice-versa.
+Storing to a table, you must use an index.
 
     | byte one
     | byte table[256] many
@@ -294,7 +294,21 @@ Storing to a table, you must use an index, and vice-versa.
     | }
     = ok
 
-Reading from a table, you must use an index, and vice-versa.
+The index must be initialized.
+
+    | byte one
+    | byte table[256] many
+    | 
+    | routine main
+    |   outputs many
+    |   trashes a, x, n, z
+    | {
+    |     ld a, 0
+    |     st a, many + x
+    | }
+    ? UnmeaningfulReadError: x
+
+Reading from a table, you must use an index.
 
     | byte one
     | 
@@ -346,6 +360,31 @@ Reading from a table, you must use an index, and vice-versa.
     | }
     = ok
 
+    | byte table[256] many
+    | 
+    | routine main
+    |   inputs many
+    |   outputs many
+    |   trashes a, x, n, z
+    | {
+    |     ld x, 0
+    |     ld a, many + x
+    | }
+    = ok
+
+The index must be initialized.
+
+    | byte table[256] many
+    | 
+    | routine main
+    |   inputs many
+    |   outputs many
+    |   trashes a, x, n, z
+    | {
+    |     ld a, many + x
+    | }
+    ? UnmeaningfulReadError: x
+
 Copying to and from a word table.
 
     | word one