From 2b4a3b22bf3fab23c25952e52d7d09d9e878b931 Mon Sep 17 00:00:00 2001
From: Matt Pharr <matt.pharr@intel.com>
Date: Thu, 21 Jun 2012 16:53:27 -0700
Subject: [PATCH] Issue an error if the user has nested foreach statements.

Partially addresses issue #280.  (We should support them properly,
but at least now we don't silently generate incorrect code.)
---
 ctx.cpp                          | 12 ++++++++++++
 tests_errors/nested-foreach.ispc | 11 +++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 tests_errors/nested-foreach.ispc

diff --git a/ctx.cpp b/ctx.cpp
index c7aaf0a2..63a4391e 100644
--- a/ctx.cpp
+++ b/ctx.cpp
@@ -584,6 +584,18 @@ FunctionEmitContext::EndLoop() {
 
 void
 FunctionEmitContext::StartForeach() {
+    // Issue an error if we're in a nested foreach...
+    for (int i = 0; i < (int)controlFlowInfo.size(); ++i) {
+        if (controlFlowInfo[i]->type == CFInfo::Foreach) {
+            Error(currentPos, "Nested \"foreach\" statements are currently illegal.");
+            break;
+            // Don't return here, however, and in turn allow the caller to
+            // do the rest of its codegen and then call EndForeach()
+            // normally--the idea being that this gives a chance to find
+            // any other errors inside the body of the foreach loop...
+        }
+    }
+
     // Store the current values of various loop-related state so that we
     // can restore it when we exit this loop.
     llvm::Value *oldMask = GetInternalMask();
diff --git a/tests_errors/nested-foreach.ispc b/tests_errors/nested-foreach.ispc
new file mode 100644
index 00000000..e3d71aa2
--- /dev/null
+++ b/tests_errors/nested-foreach.ispc
@@ -0,0 +1,11 @@
+// Nested "foreach" statements are currently illegal
+
+void func();
+
+void foo(uniform int a, uniform int b) {
+    foreach (i = 0 ... a) {
+        foreach (j = 0 ... b) {
+            func();
+        }
+    }
+}