Add explicit operator overloads for scalar/matrix cases

Fixes #103

- Previously I was relying on scalar-to-vector promotion to pick the right type in these cases, but I hadn't implemented scalar-to-matrix promotion (I should...)

- Rather than relying on promotion behavior, this change goes ahead and adds explicit overloads. I think this is probably a better decision in the long term, since one might want to support these cases for operators, while warning (or erroring) on the more general cases of implicit conversion.

- This covers matrix/scalar, scalar/matrix, vector/scalar, and scalar/vector cases

3 files changed, 89 insertions, 0 deletions

diff --git a/source/slang/slang-stdlib.cpp b/source/slang/slang-stdlib.cpp
index 3450e72d7..d266c0560 100644
--- a/source/slang/slang-stdlib.cpp
+++ b/source/slang/slang-stdlib.cpp
@@ -1833,6 +1833,27 @@ namespace Slang
                     sb << "__intrinsic_op(" << int(op.opCode) << ") matrix<" << resultType << ",N,M> operator" << op.opName << "(" << leftQual << "matrix<" << leftType << ",N,M> left, matrix<" << rightType << ",N,M> right);\n";
                     break;
                 }
+
+                // We are going to go ahead and explicitly define combined
+                // operations for the scalar-op-vector, etc. cases, rather
+                // than rely on promotion rules.
+
+                // scalar-vector and scalar-matrix
+                if (!(op.flags & ASSIGNMENT))
+                {
+                    sb << "__generic<let N : int> ";
+                    sb << "__intrinsic_op(" << int(op.opCode) << ") vector<" << resultType << ",N> operator" << op.opName << "(" << leftQual << leftType << " left, vector<" << rightType << ",N> right);\n";
+
+                    sb << "__generic<let N : int, let M : int> ";
+                    sb << "__intrinsic_op(" << int(op.opCode) << ") matrix<" << resultType << ",N,M> operator" << op.opName << "(" << leftQual << leftType << " left, matrix<" << rightType << ",N,M> right);\n";
+                }
+
+                // vector-scalar and matrix-scalar
+                sb << "__generic<let N : int> ";
+                sb << "__intrinsic_op(" << int(op.opCode) << ") vector<" << resultType << ",N> operator" << op.opName << "(" << leftQual << "vector<" << leftType << ",N> left, " << rightType << " right);\n";
+
+                sb << "__generic<let N : int, let M : int> ";
+                sb << "__intrinsic_op(" << int(op.opCode) << ") matrix<" << resultType << ",N,M> operator" << op.opName << "(" << leftQual << "matrix<" << leftType << ",N,M> left, " << rightType << " right);\n";
             }
         }
 
diff --git a/tests/bugs/gh-103.slang b/tests/bugs/gh-103.slang
new file mode 100644
index 000000000..2b10c2b3f
--- /dev/null
+++ b/tests/bugs/gh-103.slang
@@ -0,0 +1,19 @@
+//TEST:COMPARE_HLSL: -profile ps_4_0 -entry main
+
+// Ensure that matrix-times-scalar works
+
+float4x4 doIt(float4x4 a, float b)
+{
+	return a * b;
+}
+
+cbuffer C
+{
+	float4x4 a;
+	float b;	
+};
+
+float4 main() : SV_Target
+{
+	return doIt(a, b)[0];
+}
diff --git a/tests/bugs/gh-103.slang.expected b/tests/bugs/gh-103.slang.expected
new file mode 100644
index 000000000..acf3026d9
--- /dev/null
+++ b/tests/bugs/gh-103.slang.expected
@@ -0,0 +1,49 @@
+result code = 0
+standard error = {
+}
+standard output = {
+//
+// Generated by Microsoft (R) HLSL Shader Compiler 6.3.9600.16384
+//
+//
+// Buffer Definitions: 
+//
+// cbuffer C
+// {
+//
+//   float4x4 a;                        // Offset:    0 Size:    64
+//   float b;                           // Offset:   64 Size:     4
+//
+// }
+//
+//
+// Resource Bindings:
+//
+// Name                                 Type  Format         Dim Slot Elements
+// ------------------------------ ---------- ------- ----------- ---- --------
+// C                                 cbuffer      NA          NA    0        1
+//
+//
+//
+// Input signature:
+//
+// Name                 Index   Mask Register SysValue  Format   Used
+// -------------------- ----- ------ -------- -------- ------- ------
+// no Input
+//
+// Output signature:
+//
+// Name                 Index   Mask Register SysValue  Format   Used
+// -------------------- ----- ------ -------- -------- ------- ------
+// SV_Target                0   xyzw        0   TARGET   float   xyzw
+//
+ps_4_0
+dcl_constantbuffer cb0[5], immediateIndexed
+dcl_output o0.xyzw
+mul o0.x, cb0[0].x, cb0[4].x
+mul o0.y, cb0[1].x, cb0[4].x
+mul o0.z, cb0[2].x, cb0[4].x
+mul o0.w, cb0[3].x, cb0[4].x
+ret 
+// Approximately 5 instruction slots used
+}