fix problem with initializing certain array decls with single value

compiler/src/prog8/compiler/astprocessing/AstChecker.kt

@@ -626,8 +626,15 @@ internal class AstChecker(private val program: Program,
 
         val declValue = decl.value
         if(declValue!=null && decl.type==VarDeclType.VAR) {
-            if (declValue.inferType(program) isnot decl.datatype) {
+            val iDt = declValue.inferType(program)
-                err("initialisation value has incompatible type (${declValue.inferType(program)}) for the variable (${decl.datatype})")
+            if (iDt isnot decl.datatype) {
+                if(decl.datatype in ArrayDatatypes) {
+                    val eltDt = ArrayToElementTypes.getValue(decl.datatype)
+                    if(iDt isnot eltDt)
+                        err("initialisation value has incompatible type (${declValue.inferType(program)}) for the variable (${decl.datatype})")
+                } else {
+                    err("initialisation value has incompatible type (${declValue.inferType(program)}) for the variable (${decl.datatype})")
+                }
             }
         }
 
@@ -1462,6 +1469,10 @@ internal class AstChecker(private val program: Program,
             DataType.BOOL -> {
                 return true
             }
+            in ArrayDatatypes -> {
+                val eltDt = ArrayToElementTypes.getValue(targetDt)
+                return checkValueTypeAndRange(eltDt, value)
+            }
             else -> return err("value of type ${value.type} not compatible with $targetDt")
         }
         return true

compiler/test/TestAstChecks.kt

@@ -129,4 +129,20 @@ class TestAstChecks: FunSpec({
         errors.warnings.size shouldBe 0
         errors.errors[0] shouldContain "indexing requires"
     }
+
+    test("array decl with expression as size can be initialized with a single value") {
+        val text = """
+            main {
+                sub start() {
+                    const ubyte n = 40
+                    const ubyte half = n / 2
+                    ubyte[half] @shared a = 5
+                }
+            }
+        """
+        val errors = ErrorReporterForTests(keepMessagesAfterReporting = true)
+        compileText(C64Target(), true, text, writeAssembly = true, errors=errors)  shouldNotBe null
+        errors.errors.size shouldBe 0
+        errors.warnings.size shouldBe 0
+    }
 })