Fix oslc assertion on type constructor for unknown struct (#988)

The assertion was not needed, errors issue before this code is reached.

Author: lgritz

CMakeLists.txt

@@ -301,6 +301,7 @@ TESTSUITE ( aastep allowconnect-err and-or-not-synonyms arithmetic
             oslc-err-outputparamvararray oslc-err-paramdefault
             oslc-err-struct-array-init oslc-err-struct-ctr
             oslc-err-struct-dup oslc-err-struct-print
+            oslc-err-unknown-ctr
             oslc-warn-commainit
             oslc-variadic-macro
             oslc-version

src/liboslcomp/typecheck.cpp

@@ -2272,8 +2272,12 @@ OSLCompilerImpl::code_from_type (TypeSpec type) const
             out = 's';
         else if (elem == TypeDesc::NONE)
             out = 'x';
-        else
-            ASSERT (0);
+        else {
+            out = 'x';
+            // This only happens in error circumstances. Seems safe to
+            // return the code for 'void' and hope everything sorts itself
+            // out with the downstream errors.
+        }
     }
 
     if (type.is_array()) {

testsuite/oslc-err-unknown-ctr/ref/out.txt

@@ -0,0 +1,4 @@
+test.osl:4: error: Unknown struct name: mat2
+test.osl:6: error: function 'mat2' was not declared in this scope
+test.osl:6: error: No matching function call to 'mat2 (float, float, float, float)'
+FAILED test.osl

testsuite/oslc-err-unknown-ctr/run.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+# command = oslc("test.osl")
+# don't even need that -- it's automatic
+failureok = 1     # this test is expected to have oslc errors

testsuite/oslc-err-unknown-ctr/test.osl

@@ -0,0 +1,12 @@
+// No mat2 is known. This used to hit an assertion.
+// Correct behavior is understandable error message(s).
+
+mat2 rotmat(float a)
+{
+    return mat2(cos(a),sin(a),-sin(a),cos(a));
+}
+
+shader test ()
+{
+    printf ("Did not crash\n");
+}