added warning about shadowing variables

compiler/res/prog8lib/cx16/gfx2.p8

@@ -131,24 +131,24 @@ gfx2 {
         monochrome_dont_stipple_flag = not enable
     }
 
-    sub rect(uword x, uword y, uword width, uword height, ubyte color) {
+    sub rect(uword x, uword y, uword rwidth, uword rheight, ubyte color) {
-        if width==0 or height==0
+        if rwidth==0 or rheight==0
             return
-        horizontal_line(x, y, width, color)
+        horizontal_line(x, y, rwidth, color)
-        if height==1
+        if rheight==1
             return
-        horizontal_line(x, y+height-1, width, color)
+        horizontal_line(x, y+rheight-1, rwidth, color)
-        vertical_line(x, y+1, height-2, color)
+        vertical_line(x, y+1, rheight-2, color)
-        if width==1
+        if rwidth==1
             return
-        vertical_line(x+width-1, y+1, height-2, color)
+        vertical_line(x+rwidth-1, y+1, rheight-2, color)
     }
 
-    sub fillrect(uword x, uword y, uword width, uword height, ubyte color) {
+    sub fillrect(uword x, uword y, uword rwidth, uword rheight, ubyte color) {
-        if width==0
+        if rwidth==0
             return
-        repeat height {
+        repeat rheight {
-            horizontal_line(x, y, width, color)
+            horizontal_line(x, y, rwidth, color)
             y++
         }
     }
@@ -288,7 +288,7 @@ _done
         }
     }
 
-    sub vertical_line(uword x, uword y, uword height, ubyte color) {
+    sub vertical_line(uword x, uword y, uword lheight, ubyte color) {
         when active_mode {
             1, 5 -> {
                 ; monochrome, lo-res
@@ -301,7 +301,7 @@ _done
                             set_both_strides(11)    ; 40 increment = 1 line in 320 px monochrome
                         else
                             set_both_strides(12)    ; 80 increment = 1 line in 640 px monochrome
-                        repeat height {
+                        repeat lheight {
                             %asm {{
                                 lda  cx16.VERA_DATA0
                                 ora  cx16.r15L
@@ -312,14 +312,14 @@ _done
                         ; draw stippled line.
                         if x&1 {
                             y++
-                            height--
+                            lheight--
                         }
                         position2(x,y,true)
                         if active_mode==1
                             set_both_strides(12)    ; 80 increment = 2 line in 320 px monochrome
                         else
                             set_both_strides(13)    ; 160 increment = 2 line in 640 px monochrome
-                        repeat height/2 {
+                        repeat lheight/2 {
                             %asm {{
                                 lda  cx16.VERA_DATA0
                                 ora  cx16.r15L
@@ -334,7 +334,7 @@ _done
                         set_both_strides(11)    ; 40 increment = 1 line in 320 px monochrome
                     else
                         set_both_strides(12)    ; 80 increment = 1 line in 640 px monochrome
-                    repeat height {
+                    repeat lheight {
                         %asm {{
                             lda  cx16.VERA_DATA0
                             and  cx16.r15L
@@ -349,7 +349,7 @@ _done
                 position(x,y)
                 cx16.VERA_ADDR_H = cx16.VERA_ADDR_H & %00000111 | (14<<4)
                 %asm {{
-                    ldy  height
+                    ldy  lheight
                     beq  +
                     lda  color
 -                   sta  cx16.VERA_DATA0
@@ -361,14 +361,14 @@ _done
             6 -> {
                 ; highres 4c
                 ; use TWO vera adress pointers simultaneously one for reading, one for writing, so auto-increment is possible
-                if height==0
+                if lheight==0
                     return
                 position2(x,y,true)
                 set_both_strides(13)    ; 160 increment = 1 line in 640 px 4c mode
                 color &= 3
                 color <<= gfx2.plot.shift4c[lsb(x) & 3]
                 ubyte @shared mask = gfx2.plot.mask4c[lsb(x) & 3]
-                repeat height {
+                repeat lheight {
                     %asm {{
                         lda  cx16.VERA_DATA0
                         and  mask

compiler/res/prog8lib/virtual/syslib.p8

@@ -30,21 +30,21 @@ sys {
         }}
     }
 
-    sub internal_stringcopy(uword source, uword target) {
+    sub internal_stringcopy(uword source, uword tgt) {
         ; Called when the compiler wants to assign a string value to another string.
         while @(source) {
-            @(target) = @(source)
+            @(tgt) = @(source)
             source++
-            target++
+            tgt++
         }
-        @(target)=0
+        @(tgt)=0
     }
 
-    sub memcopy(uword source, uword target, uword count)  {
+    sub memcopy(uword source, uword tgt, uword count)  {
         repeat count {
-            @(target) = @(source)
+            @(tgt) = @(source)
             source++
-            target++
+            tgt++
         }
     }
 

compiler/src/prog8/compiler/astprocessing/AstIdentifiersChecker.kt

@@ -24,6 +24,10 @@ internal class AstIdentifiersChecker(private val errors: IErrorReporter,
         errors.err("name conflict '$name', also defined in ${existing.position.file} line ${existing.position.line}", position)
     }
 
+    private fun nameShadowWarning(name: String, position: Position, existing: Statement) {
+        errors.warn("name '$name' shadows occurrence at ${existing.position.file} line ${existing.position.line}", position)
+    }
+
     override fun visit(block: Block) {
         if(block.name in compTarget.machine.opcodeNames)
             errors.err("can't use a cpu opcode name as a symbol: '${block.name}'", block.position)
@@ -50,9 +54,13 @@ internal class AstIdentifiersChecker(private val errors: IErrorReporter,
         if(decl.name in compTarget.machine.opcodeNames)
             errors.err("can't use a cpu opcode name as a symbol: '${decl.name}'", decl.position)
 
-        val existing = decl.definingScope.lookup(listOf(decl.name))
+        val existing = decl.parent.definingScope.lookup(listOf(decl.name))
-        if (existing != null && existing !== decl)
+        if (existing != null && existing !== decl && existing is VarDecl) {
-            nameError(decl.name, decl.position, existing)
+            if(existing.parent!==decl.parent)
+                nameShadowWarning(decl.name, decl.position, existing)
+            else
+                nameError(decl.name, decl.position, existing)
+        }
 
         if(decl.definingBlock.name==decl.name)
             nameError(decl.name, decl.position, decl.definingBlock)
@@ -74,8 +82,12 @@ internal class AstIdentifiersChecker(private val errors: IErrorReporter,
             //    checkResult.add(NameError("builtin function name cannot be used as parameter", subroutine.position))
 
             val existing = subroutine.lookup(listOf(subroutine.name))
-            if (existing != null && existing !== subroutine)
+            if (existing != null && existing !== subroutine) {
-                nameError(subroutine.name, subroutine.position, existing)
+                if(existing.parent!==existing.parent)
+                    nameShadowWarning(subroutine.name, subroutine.position, existing)
+                else
+                    nameError(subroutine.name, subroutine.position, existing)
+            }
 
             // check that there are no local symbols (variables, labels, subs) that redefine the subroutine's parameters.
             val symbolsInSub = subroutine.allDefinedSymbols

examples/test.p8

@@ -1,14 +1,69 @@
+%import textio
+%import math
+%import string
+%import floats
 %zeropage dontuse
 
+
 ; NOTE: meant to test to virtual machine output target (use -target vitual)
 
 main {
+    ubyte value = 42
+
+    sub inline_candidate() -> ubyte {
+        return math.sin8u(value)
+    }
+
+    sub inline_candidate2() {
+        value++
+        return
+    }
+
+    sub add(ubyte first, ubyte second) -> ubyte {
+        return first + second
+    }
+
+    sub mul(ubyte first, ubyte second) -> ubyte {
+        return first * second
+    }
+
+    ubyte ix
+
     sub start() {
-        ubyte @shared xx = 11
+
-        uword addr = $5000
+        ubyte @shared value1 = inline_candidate()
-        @(addr) = @(addr) + xx
+        txt.print_ub(value) ; 42
-        xx = xx ^ 44
+        txt.spc()
-        xx = xx | 44
+        inline_candidate2()
-        xx = xx & 44
+        inline_candidate2()
+        inline_candidate2()
+        txt.print_ub(value) ; 45
+        txt.nl()
+        txt.print_ub(inline_candidate())
+        txt.nl()
+
+        ubyte @shared value=99      ; TODO compiler warning about shadowing
+        txt.print_ub(value)
+        txt.nl()
+
+        ubyte @shared add=99      ; TODO compiler warning about shadowing
+
+;        ; a "pixelshader":
+;        sys.gfx_enable(0)       ; enable lo res screen
+;        ubyte shifter
+;
+;        repeat {
+;            uword xx
+;            uword yy = 0
+;            repeat 240 {
+;                xx = 0
+;                repeat 320 {
+;                    sys.gfx_plot(xx, yy, xx*yy + shifter as ubyte)
+;                    xx++
+;                }
+;                yy++
+;            }
+;            shifter+=4
+;        }
     }
 }

examples/textelite.p8

@@ -771,36 +771,36 @@ planet {
 
     sub random_name() -> str {
         ubyte ii
-        str name = "        "       ; 8 chars max
+        str randname = "        "       ; 8 chars max
         ubyte nx = 0
         for ii in 0 to goatsoup_rnd_number() & 3 {
-            ubyte x = goatsoup_rnd_number() & $3e
+            ubyte xx = goatsoup_rnd_number() & $3e
-            if pairs0[x] != '.' {
+            if pairs0[xx] != '.' {
-                name[nx] = pairs0[x]
+                randname[nx] = pairs0[xx]
                 nx++
             }
-            x++
+            xx++
-            if pairs0[x] != '.' {
+            if pairs0[xx] != '.' {
-                name[nx] = pairs0[x]
+                randname[nx] = pairs0[xx]
                 nx++
             }
         }
-        name[nx] = 0
+        randname[nx] = 0
-        name[0] |= 32       ; uppercase first letter
+        randname[0] |= 32       ; uppercase first letter
-        return name
+        return randname
     }
 
     sub goatsoup_rnd_number() -> ubyte {
-        ubyte x = goatsoup_rnd[0] * 2
+        ubyte xx = goatsoup_rnd[0] * 2
-        uword a = x as uword + goatsoup_rnd[2]
+        uword a = xx as uword + goatsoup_rnd[2]
         if goatsoup_rnd[0] > 127
             a ++
         goatsoup_rnd[0] = lsb(a)
-        goatsoup_rnd[2] = x
+        goatsoup_rnd[2] = xx
-        x = goatsoup_rnd[1]
+        xx = goatsoup_rnd[1]
-        ubyte ac = x + goatsoup_rnd[3] + msb(a)
+        ubyte ac = xx + goatsoup_rnd[3] + msb(a)
         goatsoup_rnd[1] = ac
-        goatsoup_rnd[3] = x
+        goatsoup_rnd[3] = xx
         return ac
     }
 
@@ -1022,7 +1022,6 @@ util {
             prefixptr++
             stringptr++
         }
-        return false
     }
 
     sub print_right(ubyte width, uword s) {