Added support for {.packed.} pragma on objects

Added tests for packed and union pragmas

compiler/ast.nim

@@ -450,6 +450,7 @@ type
     tfHasMeta,        # type contains "wildcard" sub-types such as generic params
                       # or other type classes
     tfHasGCedMem,     # type contains GC'ed memory
+    tfPacked
     tfHasStatic
     tfGenericTypeParam
     tfImplicitTypeParam

compiler/ccgtypes.nim

@@ -464,24 +464,33 @@ proc getRecordDesc(m: BModule, typ: PType, name: PRope,
                    check: var TIntSet): PRope = 
   # declare the record:
   var hasField = false
-  let aStruct = structOrUnion(typ)
+
+  var attribute: PRope =
+    if tfPacked in typ.flags: toRope(CC[ccompiler].packedPragma)
+    else: nil
+
+  result = ropecg(m, CC[ccompiler].structStmtFmt, 
+    [structOrUnion(typ), name, attribute])
+
   if typ.kind == tyObject: 
+
     if typ.sons[0] == nil: 
       if (typ.sym != nil and sfPure in typ.sym.flags) or tfFinal in typ.flags: 
-        result = ropecg(m, "$1 $2 {$n", [aStruct, name])
+        appcg(m, result, " {$n", [])
       else: 
-        result = ropecg(m, "$1 $2 {$n#TNimType* m_type;$n", [aStruct, name])
+        appcg(m, result, " {$n#TNimType* m_type;$n", [name, attribute])
         hasField = true
     elif gCmd == cmdCompileToCpp: 
-      result = ropecg(m, "$1 $2 : public $3 {$n", 
-                      [aStruct, name, getTypeDescAux(m, typ.sons[0], check)])
+      appcg(m, result, " : public $1 {$n", 
+                      [getTypeDescAux(m, typ.sons[0], check)])
       hasField = true
     else: 
-      result = ropecg(m, "$1 $2 {$n  $3 Sup;$n", 
-                      [aStruct, name, getTypeDescAux(m, typ.sons[0], check)])
+      appcg(m, result, " {$n  $1 Sup;$n", 
+                      [getTypeDescAux(m, typ.sons[0], check)])
       hasField = true
   else: 
-    result = ropef("$1 $2 {$n", [aStruct, name])
+    appf(result, " {$n", [name])
+
   var desc = getRecordFields(m, typ, check)
   if (desc == nil) and not hasField: 
     appf(result, "char dummy;$n", [])

compiler/extccomp.nim

@@ -47,6 +47,8 @@ type
     pic: string,         # command for position independent code
                          # used on some platforms
     asmStmtFrmt: string, # format of ASM statement
+    structStmtFmt: string, # Format for struct statement
+    packedPragma: string,  # Attribute/pragma to make struct packed (1-byte aligned)
     props: TInfoCCProps] # properties of the C compiler
 
 
@@ -77,6 +79,8 @@ compiler gcc:
     debug: "",
     pic: "-fPIC",
     asmStmtFrmt: "asm($1);$n",
+    structStmtFmt: "$1 $3 $2 ", # struct|union [packed] $name
+    packedPragma: "__attribute__((__packed__))",
     props: {hasSwitchRange, hasComputedGoto, hasCpp, hasGcGuard, hasGnuAsm,
             hasNakedAttribute})
 
@@ -115,6 +119,8 @@ compiler vcc:
     debug: " /GZ /Zi ",
     pic: "",
     asmStmtFrmt: "__asm{$n$1$n}$n",
+    structStmtFmt: "$3$#1 $2",
+    packedPragma: "#pragma pack(1)",
     props: {hasCpp, hasAssume, hasNakedDeclspec})
 
 compiler icl:
@@ -148,6 +154,8 @@ compiler lcc:
     debug: " -g5 ",
     pic: "",
     asmStmtFrmt: "_asm{$n$1$n}$n",
+    structStmtFmt: "$1 $2",
+    packedPragma: "", # XXX: not supported yet
     props: {})
 
 compiler bcc:
@@ -170,6 +178,8 @@ compiler bcc:
     debug: "",
     pic: "",
     asmStmtFrmt: "__asm{$n$1$n}$n",
+    structStmtFmt: "$1 $2",
+    packedPragma: "", # XXX: not supported yet
     props: {hasCpp})
 
 compiler dmc:
@@ -192,6 +202,8 @@ compiler dmc:
     debug: " -g ",
     pic: "",
     asmStmtFrmt: "__asm{$n$1$n}$n",
+    structStmtFmt: "$3$n$1 $2",
+    packedPragma: "#pragma pack(1)",
     props: {hasCpp})
 
 compiler wcc:
@@ -214,6 +226,8 @@ compiler wcc:
     debug: " -d2 ",
     pic: "",
     asmStmtFrmt: "__asm{$n$1$n}$n",
+    structStmtFmt: "$1 $2",
+    packedPragma: "", # XXX: not supported yet
     props: {hasCpp})
 
 compiler tcc:
@@ -236,6 +250,8 @@ compiler tcc:
     debug: " -g ",
     pic: "",
     asmStmtFrmt: "__asm{$n$1$n}$n",
+    structStmtFmt: "$1 $2",
+    packedPragma: "", # XXX: not supported yet
     props: {hasSwitchRange, hasComputedGoto})
 
 compiler pcc:
@@ -259,6 +275,8 @@ compiler pcc:
     debug: " -Zi ",
     pic: "",
     asmStmtFrmt: "__asm{$n$1$n}$n",
+    structStmtFmt: "$1 $2",
+    packedPragma: "", # XXX: not supported yet
     props: {})
 
 compiler ucc:
@@ -281,6 +299,8 @@ compiler ucc:
     debug: "",
     pic: "",
     asmStmtFrmt: "__asm{$n$1$n}$n",
+    structStmtFmt: "$1 $2",
+    packedPragma: "", # XXX: not supported yet
     props: {})
 
 const 

compiler/pragmas.nim

@@ -52,7 +52,7 @@ const
   typePragmas* = {wImportc, wExportc, wDeprecated, wMagic, wAcyclic, wNodecl, 
     wPure, wHeader, wCompilerproc, wFinal, wSize, wExtern, wShallow,
     wImportCpp, wImportObjC, wError, wIncompleteStruct, wByCopy, wByRef,
-    wInheritable, wGensym, wInject, wRequiresInit, wUnchecked, wUnion}
+    wInheritable, wGensym, wInject, wRequiresInit, wUnchecked, wUnion, wPacked}
   fieldPragmas* = {wImportc, wExportc, wDeprecated, wExtern, 
     wImportCpp, wImportObjC, wError}
   varPragmas* = {wImportc, wExportc, wVolatile, wRegister, wThreadVar, wNodecl, 
@@ -655,6 +655,10 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: int,
           incl(sym.flags, sfThread)
           incl(sym.flags, sfProcvar)
           if sym.typ != nil: incl(sym.typ.flags, tfThread)
+        of wPacked:
+          noVal(it)
+          if sym.typ == nil: invalidPragma(it)
+          else: incl(sym.typ.flags, tfPacked)
         of wHint: message(it.info, hintUser, expectStrLit(c, it))
         of wWarning: message(it.info, warnUser, expectStrLit(c, it))
         of wError: 

compiler/semexprs.nim

@@ -921,7 +921,7 @@ const tyTypeParamsHolders = {tyGenericInst, tyCompositeTypeClass}
 proc readTypeParameter(c: PContext, typ: PType,
                        paramName: PIdent, info: TLineInfo): PNode =
   let ty = if typ.kind == tyGenericInst: typ.skipGenericAlias
-           else: (internalAssert typ.kind == tyCompositeTypeClass; typ.sons[1])
+           else: (internalAssert(typ.kind == tyCompositeTypeClass); typ.sons[1])
   
   let tbody = ty.sons[0]
   for s in countup(0, tbody.len-2):

compiler/semtypes.nim

@@ -204,7 +204,7 @@ proc nMinusOne(n: PNode): PNode =
     n])
 
 proc makeRangeWithStaticExpr(c: PContext, n: PNode): PType =
-  let intType = getSysType tyInt
+  let intType = getSysType(tyInt)
   result = newTypeS(tyRange, c)
   result.sons = @[intType]
   result.n = newNode(nkRange, n.info, @[

compiler/wordrecg.nim

@@ -72,7 +72,7 @@ type
     wPrivate, wProtected, wPublic, wRegister, wReinterpret_cast,
     wShort, wSigned, wSizeof, wStatic_cast, wStruct, wSwitch,
     wThis, wThrow, wTrue, wTypedef, wTypeid, wTypename,
-    wUnion, wUnsigned, wVirtual, wVoid, wVolatile, wWchar_t,
+    wUnion, wPacked, wUnsigned, wVirtual, wVoid, wVolatile, wWchar_t,
 
     wAlignas, wAlignof, wConstexpr, wDecltype, wNullptr, wNoexcept,
     wThread_local, wStatic_assert, wChar16_t, wChar32_t,
@@ -155,7 +155,7 @@ const
     "private", "protected", "public", "register", "reinterpret_cast",
     "short", "signed", "sizeof", "static_cast", "struct", "switch",
     "this", "throw", "true", "typedef", "typeid",
-    "typename", "union", "unsigned", "virtual", "void", "volatile",
+    "typename", "union", "packed", "unsigned", "virtual", "void", "volatile",
     "wchar_t",
 
     "alignas", "alignof", "constexpr", "decltype", "nullptr", "noexcept",

tests/objects/tobjpragma.nim

@@ -0,0 +1,49 @@
+discard """
+  file: "tobjpragma.nim"
+  output: '''2
+3
+9
+257
+1
+2
+3'''
+"""
+
+# Test 
+
+type
+  Foo {.packed.} = object
+    a: int8
+    b: int8
+
+  Bar {.packed.} = object
+    a: int8
+    b: int16   
+    
+  Daz {.packed.} = object
+    a: int32
+    b: int8 
+    c: int32  
+
+
+var f = Foo(a: 1, b: 1)
+var b: Bar
+var d: Daz
+
+echo sizeof(f)
+echo sizeof(b)
+echo sizeof(d)
+echo (cast[ptr int16](f.addr)[])
+
+type
+  Union {.union.} = object
+    a: int8
+    b: int8
+
+var u: Union
+u.a = 1
+echo u.b
+u.a = 2
+echo u.b
+u.b = 3
+echo u.a