SIZEOF("Section") and STARTOF("Section") can be known

Fixes #890

test/asm/section-sizeof-startof.asm

@@ -1,8 +1,33 @@
 SECTION "sect", ROMX[$4567], BANK[$23]
 	ds 42
 
+W = BANK("sect")
+X = SIZEOF("sect") ; unknown
+Y = STARTOF("sect")
+
+	println "sect1: {W} {X} {Y}"
+
+SECTION "sect2", ROMX
+
 W = BANK("sect")
 X = SIZEOF("sect")
 Y = STARTOF("sect")
 
-	println "{W} {X} {Y}"
+	println "sect1: {W} {X} {Y}"
+
+PUSHS
+SECTION FRAGMENT "sect3", ROMX[$4567], BANK[$12]
+
+W = BANK("sect2") ; unknown
+X = SIZEOF("sect2") ; unknown
+Y = STARTOF("sect2") ; unknown
+
+	println "sect2: {W} {X} {Y}"
+
+POPS
+
+W = BANK("sect3")
+X = SIZEOF("sect3") ; unknown
+Y = STARTOF("sect3")
+
+	println "sect3: {W} {X} {Y}"

test/asm/section-sizeof-startof.err

@@ -1,5 +1,11 @@
 ERROR: section-sizeof-startof.asm(5):
     Expected constant expression: Section "sect"'s size is not known
-ERROR: section-sizeof-startof.asm(6):
-    Expected constant expression: Section "sect"'s start is not known
-error: Assembly aborted (2 errors)!
+ERROR: section-sizeof-startof.asm(21):
+    Expected constant expression: Section "sect2"'s bank is not known
+ERROR: section-sizeof-startof.asm(22):
+    Expected constant expression: Section "sect2"'s size is not known
+ERROR: section-sizeof-startof.asm(23):
+    Expected constant expression: Section "sect2"'s start is not known
+ERROR: section-sizeof-startof.asm(30):
+    Expected constant expression: Section "sect3"'s size is not known
+error: Assembly aborted (5 errors)!

test/asm/section-sizeof-startof.out

@@ -1 +1,4 @@
-$23 $0 $0
+sect1: $23 $0 $4567
+sect1: $23 $2A $4567
+sect2: $0 $0 $0
+sect3: $12 $0 $4567