Merge pull request #490 from ISSOtm/const

Implement `ISCONST`, reporting compile-time constness

test/asm/isconst.asm

@@ -0,0 +1,29 @@
+
+TEST_NUM = 0
+
+test_expr: MACRO
+TEST_NUM = TEST_NUM + 1
+
+IS_CONST = ISCONST(\1)
+	PRINTT "Test #{d:TEST_NUM}: ISCONST reports {IS_CONST}\n"
+	IF (\1) || 1 ; Only test if the expression can be evaluated
+		WARN "Test #{d:TEST_NUM}: Compile-time constant"
+	ENDC
+ENDM
+
+	test_expr 1
+	test_expr UnknownLabel
+
+SECTION "fixed", WRAM0[$CAFE]
+
+FixedLabel:
+	ds 42
+	test_expr FixedLabel
+	test_expr @ - FixedLabel
+
+SECTION "floating", WRAMX
+
+FloatingLabel:
+	ds 69
+	test_expr FloatingLabel
+	test_expr @ - FloatingLabel

test/asm/isconst.err

@@ -0,0 +1,13 @@
+warning: isconst.asm(14) -> isconst.asm::test_expr(10): [-Wuser]
+    Test #1: Compile-time constant
+ERROR: isconst.asm(15) -> isconst.asm::test_expr(9):
+    Expected constant expression: 'UnknownLabel' is not constant at assembly time
+warning: isconst.asm(21) -> isconst.asm::test_expr(10): [-Wuser]
+    Test #3: Compile-time constant
+warning: isconst.asm(22) -> isconst.asm::test_expr(10): [-Wuser]
+    Test #4: Compile-time constant
+ERROR: isconst.asm(28) -> isconst.asm::test_expr(9):
+    Expected constant expression: 'FloatingLabel' is not constant at assembly time
+warning: isconst.asm(29) -> isconst.asm::test_expr(10): [-Wuser]
+    Test #6: Compile-time constant
+error: Assembly aborted (2 errors)!

test/asm/isconst.out

@@ -0,0 +1,6 @@
+Test #1: ISCONST reports $1
+Test #2: ISCONST reports $0
+Test #3: ISCONST reports $1
+Test #4: ISCONST reports $1
+Test #5: ISCONST reports $0
+Test #6: ISCONST reports $1