fix crash: byte c = if a < b -1 else 1 "both values should be the same type"

compiler/src/prog8/compiler/astprocessing/TypecastsAdder.kt

@@ -383,6 +383,25 @@ class TypecastsAdder(val program: Program, val options: CompilationOptions, val
         return noModifications
     }
 
+    override fun after(ifExpr: IfExpression, parent: Node): Iterable<IAstModification> {
+        val trueDt = ifExpr.truevalue.inferType(program)
+        val falseDt = ifExpr.falsevalue.inferType(program)
+        if (trueDt != falseDt) {
+            val (commonDt, toFix) = BinaryExpression.commonDatatype(
+                trueDt.getOr(DataType.UNDEFINED),
+                falseDt.getOr(DataType.UNDEFINED),
+                ifExpr.truevalue,
+                ifExpr.falsevalue
+            )
+            if (toFix != null) {
+                val modifications = mutableListOf<IAstModification>()
+                addTypecastOrCastedValueModification(modifications, toFix, commonDt, ifExpr)
+                return modifications
+            }
+        }
+        return noModifications
+    }
+
     private fun adjustRangeDts(
         range: RangeExpression,
         fromConst: NumericLiteral?,

compiler/test/TestTypecasts.kt

@@ -887,4 +887,26 @@ main {
         errors.errors[0] shouldContain "17:16: type UBYTE of return value doesn't match subroutine's return type BYTE"
         errors.errors[1] shouldContain "20:16: type UWORD of return value doesn't match subroutine's return type WORD"
     }
+
+    test("if-expression adjusts different value types to common type") {
+        val src="""
+main {
+    sub start() {
+        cx16.r0sL = if cx16.r0L < cx16.r1L -1 else 1
+    }
+}"""
+
+        val errors = ErrorReporterForTests()
+        val result = compileText(C64Target(), false, src, writeAssembly = false, errors = errors)!!
+        val program = result.compilerAst
+        val st = program.entrypoint.statements
+        st.size shouldBe 1
+        val assign = st[0] as Assignment
+        assign.target.inferType(program).getOr(DataType.UNDEFINED) shouldBe DataType.BYTE
+        val ifexpr = assign.value as IfExpression
+        ifexpr.truevalue.inferType(program).getOr(DataType.UNDEFINED) shouldBe DataType.BYTE
+        ifexpr.falsevalue.inferType(program).getOr(DataType.UNDEFINED) shouldBe DataType.BYTE
+        ifexpr.truevalue shouldBe instanceOf<NumericLiteral>()
+        ifexpr.falsevalue shouldBe instanceOf<NumericLiteral>()
+    }
 })

examples/test.p8

@@ -1,26 +1,8 @@
 %import textio
+%option no_sysinit
 
 main {
     sub start() {
-        myblock.printit()
-        myblock2.printit2()
-    }
-}
-
-myblock {
-    sub printit() {
-        txt.print_uwhex(&printit, true)
-        txt.nl()
-        txt.print_uwhex(&myblock, true)
-        txt.nl()
-    }
-}
-
-myblock2 {
-    sub printit2() {
-        txt.print_uwhex(&printit2, true)
-        txt.nl()
-        txt.print_uwhex(&myblock2, true)
-        txt.nl()
+        cx16.r0s = if cx16.r0L < cx16.r1L -1 else 1
     }
 }