'constructor' pragma for C++ support

compiler/ast.nim

@@ -257,7 +257,7 @@ type
     sfThread,         # proc will run as a thread
                       # variable is a thread variable
     sfCompileTime,    # proc can be evaluated at compile time
-    sfMerge,          # proc can be merged with itself
+    sfConstructor,    # proc is a C++ constructor
     sfDeadCodeElim,   # dead code elimination for the module is turned on
     sfBorrow,         # proc is borrowed
     sfInfixCall,      # symbol needs infix call syntax in target language;
@@ -663,7 +663,9 @@ type
     locOther                  # location is something other
   TLocFlag* = enum
     lfIndirect,               # backend introduced a pointer
-    lfParamCopy,              # backend introduced a parameter copy (LLVM)
+    lfFullExternalName, # only used when 'gCmd == cmdPretty': Indicates
+      # that the symbol has been imported via 'importc: "fullname"' and
+      # no format string.
     lfNoDeepCopy,             # no need for a deep copy
     lfNoDecl,                 # do not declare it in C
     lfDynamicLib,             # link symbol to dynamic library
@@ -915,10 +917,6 @@ const
 
   skIterators* = {skIterator, skClosureIterator}
 
-  lfFullExternalName* = lfParamCopy # \
-    # only used when 'gCmd == cmdPretty': Indicates that the symbol has been
-    # imported via 'importc: "fullname"' and no format string.
-
 var ggDebug* {.deprecated.}: bool ## convenience switch for trying out things
 
 proc isCallExpr*(n: PNode): bool =

compiler/ccgstmts.nim

@@ -202,7 +202,8 @@ proc genSingleVar(p: BProc, a: PNode) =
       genVarPrototypeAux(generatedHeader, v)
     registerGcRoot(p, v)
   else:
-    let imm = isAssignedImmediately(a.sons[2])
+    let value = a.sons[2]
+    let imm = isAssignedImmediately(value)
     if imm and p.module.compileToCpp and p.splitDecls == 0 and
         not containsHiddenPointer(v.typ):
       # C++ really doesn't like things like 'Foo f; f = x' as that invokes a
@@ -211,8 +212,19 @@ proc genSingleVar(p: BProc, a: PNode) =
       genLineDir(p, a)
       let decl = localVarDecl(p, v)
       var tmp: TLoc
-      initLocExprSingleUse(p, a.sons[2], tmp)
-      lineF(p, cpsStmts, "$# = $#;$n", decl, tmp.rdLoc)
+      if value.kind in nkCallKinds and value[0].kind == nkSym and
+           sfConstructor in value[0].sym.flags:
+        var params: PRope
+        let typ = skipTypes(value.sons[0].typ, abstractInst)
+        assert(typ.kind == tyProc)
+        for i in 1.. <value.len:
+          if params != nil: params.app(~", ")
+          assert(sonsLen(typ) == sonsLen(typ.n))
+          app(params, genOtherArg(p, value, i, typ))
+        lineF(p, cpsStmts, "$#($#);$n", decl, params)
+      else:
+        initLocExprSingleUse(p, value, tmp)
+        lineF(p, cpsStmts, "$# = $#;$n", decl, tmp.rdLoc)
       return
     assignLocalVar(p, v)
     initLocalVar(p, v, imm)

compiler/cgen.nim

@@ -358,17 +358,6 @@ proc deinitGCFrame(p: BProc): PRope =
     result = ropecg(p.module,
                     "if (((NU)&GCFRAME) < 4096) #nimGCFrame(&GCFRAME);$n")
 
-proc allocParam(p: BProc, s: PSym) =
-  assert(s.kind == skParam)
-  if lfParamCopy notin s.loc.flags:
-    inc(p.labels)
-    var tmp = con("%LOC", toRope(p.labels))
-    incl(s.loc.flags, lfParamCopy)
-    incl(s.loc.flags, lfIndirect)
-    lineF(p, cpsInit, "$1 = alloca $3$n" & "store $3 $2, $3* $1$n",
-         [tmp, s.loc.r, getTypeDesc(p.module, s.loc.t)])
-    s.loc.r = tmp
-
 proc localDebugInfo(p: BProc, s: PSym) =
   if {optStackTrace, optEndb} * p.options != {optStackTrace, optEndb}: return
   # XXX work around a bug: No type information for open arrays possible:
@@ -471,6 +460,7 @@ proc putLocIntoDest(p: BProc, d: var TLoc, s: TLoc)
 proc genAssignment(p: BProc, dest, src: TLoc, flags: TAssignmentFlags)
 proc intLiteral(i: BiggestInt): PRope
 proc genLiteral(p: BProc, n: PNode): PRope
+proc genOtherArg(p: BProc; ri: PNode; i: int; typ: PType): PRope
 
 proc initLocExpr(p: BProc, e: PNode, result: var TLoc) =
   initLoc(result, locNone, e.typ, OnUnknown)

compiler/pragmas.nim

@@ -25,7 +25,7 @@ const
     wBorrow, wExtern, wImportCompilerProc, wThread, wImportCpp, wImportObjC,
     wAsmNoStackFrame, wError, wDiscardable, wNoInit, wDestructor, wCodegenDecl,
     wGensym, wInject, wRaises, wTags, wLocks, wDelegator, wGcSafe,
-    wOverride}
+    wOverride, wConstructor}
   converterPragmas* = procPragmas
   methodPragmas* = procPragmas
   templatePragmas* = {wImmediate, wDeprecated, wError, wGensym, wInject, wDirty,
@@ -665,8 +665,11 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: int,
           incl(sym.flags, sfGlobal)
           incl(sym.flags, sfPure)
         of wMerge:
+          # only supported for backwards compat, doesn't do anything anymore
           noVal(it)
-          incl(sym.flags, sfMerge)
+        of wConstructor:
+          noVal(it)
+          incl(sym.flags, sfConstructor)
         of wHeader:
           var lib = getLib(c, libHeader, getStrLitNode(c, it))
           addToLib(lib, sym)

compiler/transf.nim

@@ -579,8 +579,7 @@ proc getMergeOp(n: PNode): PSym =
   case n.kind
   of nkCall, nkHiddenCallConv, nkCommand, nkInfix, nkPrefix, nkPostfix,
      nkCallStrLit:
-    if (n.sons[0].kind == nkSym) and (n.sons[0].sym.kind == skProc) and
-        (sfMerge in n.sons[0].sym.flags):
+    if n.sons[0].kind == nkSym and n.sons[0].sym.magic == mConStrStr:
       result = n.sons[0].sym
   else: discard
 

compiler/wordrecg.nim

@@ -13,44 +13,44 @@
 # does not support strings. Without this the code would
 # be slow and unreadable.
 
-import 
+import
   hashes, strutils, idents
 
 # Keywords must be kept sorted and within a range
 
 type
-  TSpecialWord* = enum 
-    wInvalid, 
-    
-    wAddr, wAnd, wAs, wAsm, wAtomic, 
-    wBind, wBlock, wBreak, wCase, wCast, wConst, 
-    wContinue, wConverter, wDefer, wDiscard, wDistinct, wDiv, wDo, 
+  TSpecialWord* = enum
+    wInvalid,
+
+    wAddr, wAnd, wAs, wAsm, wAtomic,
+    wBind, wBlock, wBreak, wCase, wCast, wConst,
+    wContinue, wConverter, wDefer, wDiscard, wDistinct, wDiv, wDo,
     wElif, wElse, wEnd, wEnum, wExcept, wExport,
-    wFinally, wFor, wFrom, wFunc, wGeneric, wIf, wImport, wIn, 
+    wFinally, wFor, wFrom, wFunc, wGeneric, wIf, wImport, wIn,
     wInclude, wInterface, wIs, wIsnot, wIterator, wLet,
-    wMacro, wMethod, wMixin, wMod, wNil, 
-    wNot, wNotin, wObject, wOf, wOr, wOut, wProc, wPtr, wRaise, wRef, wReturn, 
-    wShl, wShr, wStatic, wTemplate, wTry, wTuple, wType, wUsing, wVar, 
+    wMacro, wMethod, wMixin, wMod, wNil,
+    wNot, wNotin, wObject, wOf, wOr, wOut, wProc, wPtr, wRaise, wRef, wReturn,
+    wShl, wShr, wStatic, wTemplate, wTry, wTuple, wType, wUsing, wVar,
     wWhen, wWhile, wWith, wWithout, wXor, wYield,
-    
+
     wColon, wColonColon, wEquals, wDot, wDotDot,
     wStar, wMinus,
     wMagic, wThread, wFinal, wProfiler, wObjChecks,
 
     wDestroy,
-    
-    wImmediate, wDestructor, wDelegator, wOverride,
+
+    wImmediate, wConstructor, wDestructor, wDelegator, wOverride,
     wImportCpp, wImportObjC,
     wImportCompilerProc,
     wImportc, wExportc, wIncompleteStruct, wRequiresInit,
     wAlign, wNodecl, wPure, wSideeffect, wHeader,
-    wNosideeffect, wGcSafe, wNoreturn, wMerge, wLib, wDynlib, 
-    wCompilerproc, wProcVar, 
-    wFatal, wError, wWarning, wHint, wLine, wPush, wPop, wDefine, wUndef, 
-    wLinedir, wStacktrace, wLinetrace, wLink, wCompile, 
-    wLinksys, wDeprecated, wVarargs, wCallconv, wBreakpoint, wDebugger, 
-    wNimcall, wStdcall, wCdecl, wSafecall, wSyscall, wInline, wNoInline, 
-    wFastcall, wClosure, wNoconv, wOn, wOff, wChecks, wRangechecks, 
+    wNosideeffect, wGcSafe, wNoreturn, wMerge, wLib, wDynlib,
+    wCompilerproc, wProcVar,
+    wFatal, wError, wWarning, wHint, wLine, wPush, wPop, wDefine, wUndef,
+    wLinedir, wStacktrace, wLinetrace, wLink, wCompile,
+    wLinksys, wDeprecated, wVarargs, wCallconv, wBreakpoint, wDebugger,
+    wNimcall, wStdcall, wCdecl, wSafecall, wSyscall, wInline, wNoInline,
+    wFastcall, wClosure, wNoconv, wOn, wOff, wChecks, wRangechecks,
     wBoundchecks, wOverflowchecks, wNilchecks,
     wFloatchecks, wNanChecks, wInfChecks,
     wAssertions, wPatterns, wWarnings,
@@ -59,11 +59,11 @@ type
     wPragma,
     wCompileTime, wNoInit,
     wPassc, wPassl, wBorrow, wDiscardable,
-    wFieldChecks, 
-    wWatchPoint, wSubsChar, 
-    wAcyclic, wShallow, wUnroll, wLinearScanEnd, wComputedGoto, 
+    wFieldChecks,
+    wWatchPoint, wSubsChar,
+    wAcyclic, wShallow, wUnroll, wLinearScanEnd, wComputedGoto,
     wInjectStmt, wExperimental,
-    wWrite, wGensym, wInject, wDirty, wInheritable, wThreadVar, wEmit, 
+    wWrite, wGensym, wInject, wDirty, wInheritable, wThreadVar, wEmit,
     wAsmNoStackFrame,
     wImplicitStatic, wGlobal, wCodegenDecl, wUnchecked, wGuard, wLocks,
 
@@ -82,38 +82,38 @@ type
     wStdIn, wStdOut, wStdErr,
 
     wInOut, wByCopy, wByRef, wOneWay,
-    
+
   TSpecialWords* = set[TSpecialWord]
 
-const 
+const
   oprLow* = ord(wColon)
   oprHigh* = ord(wDotDot)
-  
+
   nimKeywordsLow* = ord(wAsm)
   nimKeywordsHigh* = ord(wYield)
-  
+
   ccgKeywordsLow* = ord(wAuto)
   ccgKeywordsHigh* = ord(wOneWay)
-  
+
   cppNimSharedKeywords* = {
     wAsm, wBreak, wCase, wConst, wContinue, wDo, wElse, wEnum, wExport,
     wFor, wIf, wReturn, wStatic, wTemplate, wTry, wWhile, wUsing}
 
-  specialWords*: array[low(TSpecialWord)..high(TSpecialWord), string] = ["", 
-    
-    "addr", "and", "as", "asm", "atomic", 
-    "bind", "block", "break", "case", "cast", 
+  specialWords*: array[low(TSpecialWord)..high(TSpecialWord), string] = ["",
+
+    "addr", "and", "as", "asm", "atomic",
+    "bind", "block", "break", "case", "cast",
     "const", "continue", "converter",
     "defer", "discard", "distinct", "div", "do",
-    "elif", "else", "end", "enum", "except", "export", 
-    "finally", "for", "from", "func", "generic", "if", 
+    "elif", "else", "end", "enum", "except", "export",
+    "finally", "for", "from", "func", "generic", "if",
     "import", "in", "include", "interface", "is", "isnot", "iterator",
     "let",
     "macro", "method", "mixin", "mod", "nil", "not", "notin",
-    "object", "of", "or", 
+    "object", "of", "or",
     "out", "proc", "ptr", "raise", "ref", "return",
     "shl", "shr", "static",
-    "template", "try", "tuple", "type", "using", "var", 
+    "template", "try", "tuple", "type", "using", "var",
     "when", "while", "with", "without", "xor",
     "yield",
 
@@ -122,22 +122,22 @@ const
     "magic", "thread", "final", "profiler", "objchecks",
 
     "destroy",
-    
-    "immediate", "destructor", "delegator", "override",
+
+    "immediate", "constructor", "destructor", "delegator", "override",
     "importcpp", "importobjc",
     "importcompilerproc", "importc", "exportc", "incompletestruct",
     "requiresinit", "align", "nodecl", "pure", "sideeffect",
-    "header", "nosideeffect", "gcsafe", "noreturn", "merge", "lib", "dynlib", 
-    "compilerproc", "procvar", "fatal", "error", "warning", "hint", "line", 
-    "push", "pop", "define", "undef", "linedir", "stacktrace", "linetrace", 
-    "link", "compile", "linksys", "deprecated", "varargs", 
-    "callconv", "breakpoint", "debugger", "nimcall", "stdcall", 
+    "header", "nosideeffect", "gcsafe", "noreturn", "merge", "lib", "dynlib",
+    "compilerproc", "procvar", "fatal", "error", "warning", "hint", "line",
+    "push", "pop", "define", "undef", "linedir", "stacktrace", "linetrace",
+    "link", "compile", "linksys", "deprecated", "varargs",
+    "callconv", "breakpoint", "debugger", "nimcall", "stdcall",
     "cdecl", "safecall", "syscall", "inline", "noinline", "fastcall", "closure",
-    "noconv", "on", "off", "checks", "rangechecks", "boundchecks", 
+    "noconv", "on", "off", "checks", "rangechecks", "boundchecks",
     "overflowchecks", "nilchecks",
     "floatchecks", "nanchecks", "infchecks",
 
-    "assertions", "patterns", "warnings", "hints", 
+    "assertions", "patterns", "warnings", "hints",
     "optimization", "raises", "writes", "reads", "size", "effects", "tags",
     "deadcodeelim", "safecode", "noforward",
     "pragma",
@@ -149,7 +149,7 @@ const
     "write", "gensym", "inject", "dirty", "inheritable", "threadvar", "emit",
     "asmnostackframe", "implicitstatic", "global", "codegendecl", "unchecked",
     "guard", "locks",
-    
+
     "auto", "bool", "catch", "char", "class",
     "const_cast", "default", "delete", "double",
     "dynamic_cast", "explicit", "extern", "false",
@@ -169,22 +169,22 @@ const
     "inout", "bycopy", "byref", "oneway",
     ]
 
-proc findStr*(a: openArray[string], s: string): int = 
-  for i in countup(low(a), high(a)): 
-    if cmpIgnoreStyle(a[i], s) == 0: 
+proc findStr*(a: openArray[string], s: string): int =
+  for i in countup(low(a), high(a)):
+    if cmpIgnoreStyle(a[i], s) == 0:
       return i
   result = - 1
 
-proc whichKeyword*(id: PIdent): TSpecialWord = 
+proc whichKeyword*(id: PIdent): TSpecialWord =
   if id.id < 0: result = wInvalid
   else: result = TSpecialWord(id.id)
 
-proc whichKeyword*(id: string): TSpecialWord = 
+proc whichKeyword*(id: string): TSpecialWord =
   result = whichKeyword(getIdent(id))
-  
-proc initSpecials() = 
+
+proc initSpecials() =
   # initialize the keywords:
-  for s in countup(succ(low(specialWords)), high(specialWords)): 
+  for s in countup(succ(low(specialWords)), high(specialWords)):
     getIdent(specialWords[s], hashIgnoreStyle(specialWords[s])).id = ord(s)
-  
+
 initSpecials()

doc/nimc.txt

@@ -545,6 +545,20 @@ instead:
   let x = newFoo(3, 4)
 
 
+Wrapping constructors
+~~~~~~~~~~~~~~~~~~~~~
+
+Sometimes a C++ class has a private copy constructor and so code like
+``Class c = Class(1,2);`` must not be generated but instead ``Class c(1,2);``.
+For this purpose the Nim proc that wraps a C++ constructor needs to be
+annotated with the `constructor`:idx: pragma. This pragma also helps to generate
+faster C++ code since construction then doesn't invoke the copy constructor:
+
+.. code-block:: nim
+  # a better constructor of 'Foo':
+  proc constructFoo(a, b: cint): Foo {.importcpp: "Foo(@)", constructor.}
+
+
 Wrapping destructors
 ~~~~~~~~~~~~~~~~~~~~
 
@@ -608,7 +622,7 @@ allows *sloppy* interfacing with libraries written in Objective C:
 
   - (void)greet:(long)x y:(long)dummy
   {
-	  printf("Hello, World!\n");
+    printf("Hello, World!\n");
   }
   @end