From 1da2834b1e1a49711b191f39a1352e8d8eaec04a Mon Sep 17 00:00:00 2001
From: Matt Pharr <matt.pharr@intel.com>
Date: Sun, 25 Mar 2012 13:10:12 -0700
Subject: [PATCH] Allow the last member of a struct to be an
 unsized/zero-length array.

This enables the C truck of allocating a dynamic amount of storage for
the struct in order to extend out the array to the desired length.
---
 decl.cpp                                | 19 ++++++++++---------
 tests/struct-zero-len-array-member.ispc | 24 ++++++++++++++++++++++++
 tests_errors/struct-unsized-array.ispc  |  2 +-
 3 files changed, 35 insertions(+), 10 deletions(-)
 create mode 100644 tests/struct-zero-len-array-member.ispc

diff --git a/decl.cpp b/decl.cpp
index f4382c8b..c881c7e7 100644
--- a/decl.cpp
+++ b/decl.cpp
@@ -739,15 +739,7 @@ GetStructTypesNamesPositions(const std::vector<StructDeclaration *> &sd,
             if (Type::Equal(sym->type, AtomicType::Void))
                 Error(d->pos, "\"void\" type illegal for struct member.");
 
-            const ArrayType *arrayType = 
-                dynamic_cast<const ArrayType *>(sym->type);
-            if (arrayType != NULL && arrayType->GetElementCount() == 0) {
-                Error(d->pos, "Unsized arrays aren't allowed in struct "
-                      "definitions.");
-                elementTypes->push_back(NULL);
-            }
-            else
-                elementTypes->push_back(sym->type);
+            elementTypes->push_back(sym->type);
 
             if (seenNames.find(sym->name) != seenNames.end())
                 Error(d->pos, "Struct member \"%s\" has same name as a "
@@ -759,4 +751,13 @@ GetStructTypesNamesPositions(const std::vector<StructDeclaration *> &sd,
             elementPositions->push_back(sym->pos);
         }
     }
+
+    for (int i = 0; i < (int)elementTypes->size() - 1; ++i) {
+        const ArrayType *arrayType = 
+            dynamic_cast<const ArrayType *>((*elementTypes)[i]);
+
+        if (arrayType != NULL && arrayType->GetElementCount() == 0)
+            Error((*elementPositions)[i], "Unsized arrays aren't allowed except "
+                  "for the last member in a struct definition.");
+    }
 }
diff --git a/tests/struct-zero-len-array-member.ispc b/tests/struct-zero-len-array-member.ispc
new file mode 100644
index 00000000..83e91854
--- /dev/null
+++ b/tests/struct-zero-len-array-member.ispc
@@ -0,0 +1,24 @@
+
+struct Foo {
+    float x;
+    float a[0];
+};
+
+export uniform int width() { return programCount; }
+
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    uniform int nFloats = 3+programCount;
+    varying Foo * uniform ptr = (varying Foo * uniform)(uniform new varying int32[nFloats]);
+    memset(ptr, 0, nFloats*sizeof(int32));
+    
+    for (uniform int i = 0; i < nFloats-1; ++i)
+        ptr->a[i] = i;
+    ptr->x = aFOO[programIndex]; 
+
+    RET[programIndex] = ptr->a[1+programIndex]; 
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = 1 + programIndex;
+}
diff --git a/tests_errors/struct-unsized-array.ispc b/tests_errors/struct-unsized-array.ispc
index 77553eff..7238a351 100644
--- a/tests_errors/struct-unsized-array.ispc
+++ b/tests_errors/struct-unsized-array.ispc
@@ -1,4 +1,4 @@
-// Unsized arrays aren't allowed in struct definitions
+// Unsized arrays aren't allowed except for the last member in a struct definition.
 
 struct Foo {
     float a[];