[mlir][EmitC] Fail on memrefs with 0 dims in type conversion (#111965)

This let's the type conversion fail instead of generating invalid array
types.

Author: Simon Camphausen

mlir/lib/Conversion/MemRefToEmitC/MemRefToEmitC.cpp

@@ -167,7 +167,9 @@ void mlir::populateMemRefToEmitCTypeConversion(TypeConverter &typeConverter) {
   typeConverter.addConversion(
       [&](MemRefType memRefType) -> std::optional<Type> {
         if (!memRefType.hasStaticShape() ||
-            !memRefType.getLayout().isIdentity() || memRefType.getRank() == 0) {
+            !memRefType.getLayout().isIdentity() || memRefType.getRank() == 0 ||
+            llvm::any_of(memRefType.getShape(),
+                         [](int64_t dim) { return dim == 0; })) {
           return {};
         }
         Type convertedElementType =

mlir/test/Conversion/MemRefToEmitC/memref-to-emitc-failed.mlir

@@ -41,6 +41,22 @@ func.func @zero_rank() {
 
 // -----
 
+func.func @zero_dim_rank_1() {
+  // expected-error@+1 {{failed to legalize operation 'memref.alloca'}}
+  %0 = memref.alloca() : memref<0xf32>
+  return
+}
+
+// -----
+
+func.func @zero_dim_rank_3() {
+  // expected-error@+1 {{failed to legalize operation 'memref.alloca'}}
+  %0 = memref.alloca() : memref<2x0x4xf32>
+  return
+}
+
+// -----
+
 // expected-error@+1 {{failed to legalize operation 'memref.global'}}
 memref.global "nested" constant @nested_global : memref<3x7xf32>