Fix regression of #pragma bss-name

Closes #409

cfg/sim6502.cfg

@@ -3,7 +3,7 @@ SYMBOLS {
     __STACKSIZE__: type = weak, value = $0800; # 2k stack
 }
 MEMORY {
-    ZP:     file = "",               start = $0000, size = $001A;
+    ZP:     file = "",               start = $0000, size = $001B;
     HEADER: file = %O,               start = $0000, size = $0001;
     MAIN:   file = %O, define = yes, start = $0200, size = $FDF0 - __STACKSIZE__;
 }

cfg/sim65c02.cfg

@@ -3,7 +3,7 @@ SYMBOLS {
     __STACKSIZE__: type = weak, value = $0800; # 2k stack
 }
 MEMORY {
-    ZP:     file = "",               start = $0000, size = $001A;
+    ZP:     file = "",               start = $0000, size = $001B;
     HEADER: file = %O,               start = $0000, size = $0001;
     MAIN:   file = %O, define = yes, start = $0200, size = $FDF0 - __STACKSIZE__;
 }

src/cc65/compile.c

@@ -242,8 +242,7 @@ static void Parse (void)
                             Error ("Variable `%s' has unknown size", Decl.Ident);
                         }
                         Entry->Flags &= ~(SC_STORAGE | SC_DEF);
-                    }
+                    } else {
-
                         /* A global (including static) uninitialized variable
                         ** is only a tentative definition. For example, this is valid:
                         ** int i;
@@ -251,7 +250,16 @@ static void Parse (void)
                         ** static int j;
                         ** static int j = 42;
                         ** Code for these will be generated in FinishCompile.
+                        ** For now, just save the BSS segment name
+                        ** (can be set with #pragma bss-name)
                         */
+                        const char* bssName = GetSegName (SEG_BSS);
+                        if (Entry->V.BssName && strcmp (Entry->V.BssName, bssName) != 0) {
+                            Error ("Global variable `%s' has already been defined in `%s' segment",
+                                   Entry->Name, Entry->V.BssName);
+                        }
+                        Entry->V.BssName = xstrdup (bssName);
+                    }
                 }
 
             }
@@ -418,6 +426,8 @@ void FinishCompile (void)
         } else if ((Entry->Flags & (SC_STORAGE | SC_DEF | SC_STATIC)) == (SC_STORAGE | SC_STATIC)) {
             /* Tentative definition of uninitialized global variable */
             g_usebss ();
+            SetSegName (SEG_BSS, Entry->V.BssName);
+            g_segname (SEG_BSS); /* TODO: skip if same as before */
             g_defgloblabel (Entry->Name);
             g_res (SizeOf (Entry->Type));
             /* Mark as defined, so that it will be exported not imported */

src/cc65/symentry.c

@@ -71,6 +71,7 @@ SymEntry* NewSymEntry (const char* Name, unsigned Flags)
     E->Type     = 0;
     E->Attr     = 0;
     E->AsmName  = 0;
+    E->V.BssName = 0;
     memcpy (E->Name, Name, Len+1);
 
     /* Return the new entry */

src/cc65/symentry.h

@@ -153,6 +153,8 @@ struct SymEntry {
             struct LiteralPool* LitPool;  /* Literal pool for this function */
         } F;
 
+        /* Segment name for tentantive global definitions */
+        const char*             BssName;
     } V;
     char                       Name[1]; /* Name, dynamically allocated */
 };

test/err/bss-name-conflict.c

@@ -0,0 +1,20 @@
+/*
+  !!DESCRIPTION!! conflicting bss-name pragmas
+  !!ORIGIN!!      cc65 regression tests
+  !!LICENCE!!     Public Domain
+  !!AUTHOR!!      Piotr Fusik
+*/
+
+/*
+  see: https://github.com/cc65/cc65/issues/409
+*/
+
+char oam_off;
+#pragma bss-name (push,"ZEROPAGE")
+char oam_off;
+#pragma bss-name (pop)
+
+int main(void)
+{
+    return 0;
+}

test/val/bss-name-decl.c

@@ -0,0 +1,22 @@
+/*
+  !!DESCRIPTION!! bss-name pragma not affecting declarations
+  !!ORIGIN!!      cc65 regression tests
+  !!LICENCE!!     Public Domain
+  !!AUTHOR!!      Piotr Fusik
+*/
+
+/*
+  see: https://github.com/cc65/cc65/issues/409
+*/
+
+#pragma bss-name (push,"ZEROPAGE")
+
+char n; /* only a declaration because followed by definition */
+char n = 1; /* not BSS */
+
+#pragma bss-name (pop)
+
+int main(void)
+{
+    return (unsigned) &n >= 0x100 ? 0 : 1;
+}

test/val/bss-name.c

@@ -0,0 +1,21 @@
+/*
+  !!DESCRIPTION!! bss-name pragma
+  !!ORIGIN!!      cc65 regression tests
+  !!LICENCE!!     Public Domain
+  !!AUTHOR!!      Piotr Fusik
+*/
+
+/*
+  see: https://github.com/cc65/cc65/issues/409
+*/
+
+#pragma bss-name (push,"ZEROPAGE")
+
+char zp_var;
+
+#pragma bss-name (pop)
+
+int main(void)
+{
+    return (unsigned) &zp_var < 0x100 ? 0 : 1;
+}