Merge pull request #30 from opendlang/private-this

Private this

changelog/private-this.dd

@@ -0,0 +1,24 @@
+Add experimental `private(this)` visibility attribute
+
+The `private` visibility attribute only limits access to the current module.
+While `class` encapsulation [can be ensured using package modules](https://dlang.org/blog/2018/11/06/lost-in-translation-encapsulation),
+some users dislike having to put classes into individual files to accomplish this.
+
+With the `-preview=privateThis` switch, member variables can now be marked invisible outside of the
+`class`, `struct` or `union` it's declared in.
+Note that this feature has not been accepted into the D language yet.
+
+---
+class C
+{
+    private int x;
+    private(this) int y;
+}
+
+void main()
+{
+    auto c = new C();
+    c.x++; // allowed
+    c.y++; // not allowed
+}
+---

compiler/src/dmd/access.d

@@ -236,33 +236,28 @@ bool checkAccess(Scope* sc, Package p)
  * Check whether symbols `s` is visible in `mod`.
  *
  * Params:
- *  mod = lookup origin
+ *  origin = lookup origin
  *  s = symbol to check for visibility
  * Returns: true if s is visible in mod
  */
-bool symbolIsVisible(Module mod, Dsymbol s)
+bool symbolIsVisible(Dsymbol origin, Dsymbol s)
 {
+    Module mod = origin.getAccessModule();
+
     // should sort overloads by ascending visibility instead of iterating here
     s = mostVisibleOverload(s);
     final switch (s.visible().kind)
     {
     case Visibility.Kind.undefined: return true;
     case Visibility.Kind.none: return false; // no access
+    case Visibility.Kind.privateThis: return origin == s.isMember2();
     case Visibility.Kind.private_: return s.getAccessModule() == mod;
     case Visibility.Kind.package_: return s.getAccessModule() == mod || hasPackageAccess(mod, s);
     case Visibility.Kind.protected_: return s.getAccessModule() == mod;
     case Visibility.Kind.public_, Visibility.Kind.export_: return true;
     }
 }
 
-/**
- * Same as above, but determines the lookup module from symbols `origin`.
- */
-bool symbolIsVisible(Dsymbol origin, Dsymbol s)
-{
-    return symbolIsVisible(origin.getAccessModule(), s);
-}
-
 /**
  * Same as above but also checks for protected symbols visible from scope `sc`.
  * Used for qualified name lookup.
@@ -293,6 +288,7 @@ bool checkSymbolAccess(Scope *sc, Dsymbol s)
     {
     case Visibility.Kind.undefined: return true;
     case Visibility.Kind.none: return false; // no access
+    case Visibility.Kind.privateThis: return sc.getStructClassScope() == s.isMember2();
     case Visibility.Kind.private_: return sc._module == s.getAccessModule();
     case Visibility.Kind.package_: return sc._module == s.getAccessModule() || hasPackageAccess(sc._module, s);
     case Visibility.Kind.protected_: return hasProtectedAccess(sc, s);

compiler/src/dmd/astbase.d

@@ -6777,6 +6777,7 @@ struct ASTBase
         {
             undefined,
             none,
+            privateThis,
             private_,
             package_,
             protected_,
@@ -6830,6 +6831,8 @@ struct ASTBase
             return null;
         case Visibility.Kind.none:
             return "none";
+        case Visibility.Kind.privateThis:
+            return "private(this)";
         case Visibility.Kind.private_:
             return "private";
         case Visibility.Kind.package_:

compiler/src/dmd/cli.d

@@ -937,6 +937,8 @@ dmd -cov -unittest myprog.d
             "disallow unsound immutable conversions that were formerly incorrectly permitted"),
         Feature("systemVariables", "systemVariables",
             "disable access to variables marked '@system' from @safe code"),
+        Feature("privateThis", "privateThis",
+            "add `private(this)` visibility attribute, private to the class/struct/union instead of module"),
     ];
 }
 

compiler/src/dmd/cppmanglewin.d

@@ -1311,6 +1311,7 @@ void mangleVisibility(ref OutBuffer buf, Declaration d, string privProtDef)@safe
 {
     switch (d.visibility.kind)
     {
+        case Visibility.Kind.privateThis:
         case Visibility.Kind.private_:
             buf.writeByte(privProtDef[0]);
             break;

compiler/src/dmd/dmodule.d

@@ -884,6 +884,7 @@ version (IN_LLVM)
             const bool doUnittests = global.params.parsingUnittestsRequired();
             scope p = new Parser!AST(this, buf, cast(bool) docfile, global.errorSink, &global.compileEnv, doUnittests);
             p.transitionIn = global.params.v.vin;
+            p.allowPrivateThis = global.params.privateThis;
             p.nextToken();
             p.parseModuleDeclaration();
             md = p.md;

compiler/src/dmd/dsymbol.d

@@ -136,6 +136,7 @@ struct Visibility
     {
         undefined,
         none,           // no access
+        privateThis,    // only within aggregate
         private_,
         package_,
         protected_,

compiler/src/dmd/dsymbolsem.d

@@ -2203,6 +2203,7 @@ else // !IN_LLVM
         auto loc = adjustLocForMixin(str, cd.loc, global.params.mixinOut);
         scope p = new Parser!ASTCodegen(loc, sc._module, str, false, global.errorSink, &global.compileEnv, doUnittests);
         p.transitionIn = global.params.v.vin;
+        p.allowPrivateThis = global.params.privateThis;
         p.nextToken();
 
         auto d = p.parseDeclDefs(0);
@@ -6288,6 +6289,10 @@ private extern(C++) class AddMemberVisitor : Visitor
             visd.visibility.pkg = tmp ? tmp.isPackage() : null;
             visd.pkg_identifiers = null;
         }
+        if (visd.visibility.kind == Visibility.Kind.privateThis && sds.isModule())
+        {
+            .error(visd.loc, "%s cannot be used in global scope", visd.toPrettyChars(false));
+        }
         if (visd.visibility.kind == Visibility.Kind.package_ && visd.visibility.pkg && sc._module)
         {
             Module m = sc._module;

compiler/src/dmd/expressionsem.d

@@ -7538,6 +7538,7 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor
         auto loc = adjustLocForMixin(str, exp.loc, global.params.mixinOut);
         scope p = new Parser!ASTCodegen(loc, sc._module, str, false, global.errorSink, &global.compileEnv, doUnittests);
         p.transitionIn = global.params.v.vin;
+        p.allowPrivateThis = global.params.privateThis;
         p.nextToken();
         //printf("p.loc.linnum = %d\n", p.loc.linnum);
 

compiler/src/dmd/frontend.h

@@ -435,11 +435,12 @@ struct Visibility final
     {
         undefined = 0u,
         none = 1u,
-        private_ = 2u,
-        package_ = 3u,
-        protected_ = 4u,
-        public_ = 5u,
-        export_ = 6u,
+        privateThis = 2u,
+        private_ = 3u,
+        package_ = 4u,
+        protected_ = 5u,
+        public_ = 6u,
+        export_ = 7u,
     };
 
     Kind kind;
@@ -7367,7 +7368,7 @@ struct Scope final
         linkage((LINK)1u),
         cppmangle((CPPMANGLE)0u),
         inlining(),
-        visibility(Visibility((Visibility::Kind)5u, nullptr)),
+        visibility(Visibility((Visibility::Kind)6u, nullptr)),
         explicitVisibility(),
         stc(),
         depdecl(),
@@ -7378,7 +7379,7 @@ struct Scope final
         aliasAsg()
     {
     }
-    Scope(Scope* enclosing, Module* _module = nullptr, ScopeDsymbol* scopesym = nullptr, FuncDeclaration* func = nullptr, VarDeclaration* varDecl = nullptr, Dsymbol* parent = nullptr, LabelStatement* slabel = nullptr, SwitchStatement* sw = nullptr, Statement* tryBody = nullptr, TryFinallyStatement* tf = nullptr, ScopeGuardStatement* os = nullptr, Statement* sbreak = nullptr, Statement* scontinue = nullptr, ForeachStatement* fes = nullptr, Scope* callsc = nullptr, Dsymbol* inunion = nullptr, bool nofree = false, bool inLoop = false, int32_t intypeof = 0, VarDeclaration* lastVar = nullptr, ErrorSink* eSink = nullptr, Module* minst = nullptr, TemplateInstance* tinst = nullptr, CtorFlow ctorflow = CtorFlow(), AlignDeclaration* aligndecl = nullptr, CPPNamespaceDeclaration* namespace_ = nullptr, LINK linkage = (LINK)1u, CPPMANGLE cppmangle = (CPPMANGLE)0u, PragmaDeclaration* inlining = nullptr, Visibility visibility = Visibility((Visibility::Kind)5u, nullptr), int32_t explicitVisibility = 0, uint64_t stc = 0LLU, DeprecatedDeclaration* depdecl = nullptr, uint32_t flags = 0u, UserAttributeDeclaration* userAttribDecl = nullptr, DocComment* lastdc = nullptr, void* anchorCounts = nullptr, Identifier* prevAnchor = nullptr, AliasDeclaration* aliasAsg = nullptr) :
+    Scope(Scope* enclosing, Module* _module = nullptr, ScopeDsymbol* scopesym = nullptr, FuncDeclaration* func = nullptr, VarDeclaration* varDecl = nullptr, Dsymbol* parent = nullptr, LabelStatement* slabel = nullptr, SwitchStatement* sw = nullptr, Statement* tryBody = nullptr, TryFinallyStatement* tf = nullptr, ScopeGuardStatement* os = nullptr, Statement* sbreak = nullptr, Statement* scontinue = nullptr, ForeachStatement* fes = nullptr, Scope* callsc = nullptr, Dsymbol* inunion = nullptr, bool nofree = false, bool inLoop = false, int32_t intypeof = 0, VarDeclaration* lastVar = nullptr, ErrorSink* eSink = nullptr, Module* minst = nullptr, TemplateInstance* tinst = nullptr, CtorFlow ctorflow = CtorFlow(), AlignDeclaration* aligndecl = nullptr, CPPNamespaceDeclaration* namespace_ = nullptr, LINK linkage = (LINK)1u, CPPMANGLE cppmangle = (CPPMANGLE)0u, PragmaDeclaration* inlining = nullptr, Visibility visibility = Visibility((Visibility::Kind)6u, nullptr), int32_t explicitVisibility = 0, uint64_t stc = 0LLU, DeprecatedDeclaration* depdecl = nullptr, uint32_t flags = 0u, UserAttributeDeclaration* userAttribDecl = nullptr, DocComment* lastdc = nullptr, void* anchorCounts = nullptr, Identifier* prevAnchor = nullptr, AliasDeclaration* aliasAsg = nullptr) :
         enclosing(enclosing),
         _module(_module),
         scopesym(scopesym),
@@ -8194,6 +8195,7 @@ struct Param final
     bool fix16997;
     FeatureState dtorFields;
     FeatureState systemVariables;
+    bool privateThis;
     CHECKENABLE useInvariants;
     CHECKENABLE useIn;
     CHECKENABLE useOut;
@@ -8270,6 +8272,7 @@ struct Param final
         shortenedMethods(true),
         fixImmutableConv(),
         fix16997(true),
+        privateThis(),
         useInvariants((CHECKENABLE)0u),
         useIn((CHECKENABLE)0u),
         useOut((CHECKENABLE)0u),
@@ -8309,7 +8312,7 @@ struct Param final
         mapfile()
     {
     }
-    Param(bool obj, bool multiobj = false, bool trace = false, bool tracegc = false, bool vcg_ast = false, DiagnosticReporting useDeprecated = (DiagnosticReporting)1u, bool useUnitTests = false, bool useInline = false, bool release = false, bool preservePaths = false, DiagnosticReporting warnings = (DiagnosticReporting)2u, bool cov = false, uint8_t covPercent = 0u, bool ctfe_cov = false, bool ignoreUnsupportedPragmas = true, bool useModuleInfo = true, bool useTypeInfo = true, bool useExceptions = true, bool useGC = true, bool betterC = false, bool addMain = false, bool allInst = false, bool bitfields = false, CppStdRevision cplusplus = (CppStdRevision)201103u, Help help = Help(), Verbose v = Verbose(), FeatureState useDIP25 = (FeatureState)2u, FeatureState useDIP1000 = (FeatureState)0u, bool ehnogc = false, bool useDIP1021 = false, FeatureState fieldwise = (FeatureState)0u, bool fixAliasThis = false, FeatureState rvalueRefParam = (FeatureState)0u, FeatureState noSharedAccess = (FeatureState)0u, bool previewIn = false, bool inclusiveInContracts = false, bool shortenedMethods = true, bool fixImmutableConv = false, bool fix16997 = true, FeatureState dtorFields = (FeatureState)0u, FeatureState systemVariables = (FeatureState)0u, CHECKENABLE useInvariants = (CHECKENABLE)0u, CHECKENABLE useIn = (CHECKENABLE)0u, CHECKENABLE useOut = (CHECKENABLE)0u, CHECKENABLE useArrayBounds = (CHECKENABLE)0u, CHECKENABLE useAssert = (CHECKENABLE)0u, CHECKENABLE useSwitchError = (CHECKENABLE)0u, CHECKENABLE boundscheck = (CHECKENABLE)0u, CHECKACTION checkAction = (CHECKACTION)0u, _d_dynamicArray< const char > argv0 = {}, Array<const char* > modFileAliasStrings = Array<const char* >(), Array<const char* >* imppath = nullptr, Array<const char* >* fileImppath = nullptr, _d_dynamicArray< const char > objdir = {}, _d_dynamicArray< const char > objname = {}, _d_dynamicArray< const char > libname = {}, Output ddoc = Output(), Output dihdr = Output(), Output cxxhdr = Output(), Output json = Output(), JsonFieldFlags jsonFieldFlags = (JsonFieldFlags)0u, Output makeDeps = Output(), Output mixinOut = Output(), Output moduleDeps = Output(), uint32_t debuglevel = 0u, uint32_t versionlevel = 0u, bool run = false, Array<const char* > runargs = Array<const char* >(), Array<const char* > cppswitches = Array<const char* >(), const char* cpp = nullptr, Array<const char* > objfiles = Array<const char* >(), Array<const char* > linkswitches = Array<const char* >(), Array<bool > linkswitchIsForCC = Array<bool >(), Array<const char* > libfiles = Array<const char* >(), Array<const char* > dllfiles = Array<const char* >(), _d_dynamicArray< const char > deffile = {}, _d_dynamicArray< const char > resfile = {}, _d_dynamicArray< const char > exefile = {}, _d_dynamicArray< const char > mapfile = {}) :
+    Param(bool obj, bool multiobj = false, bool trace = false, bool tracegc = false, bool vcg_ast = false, DiagnosticReporting useDeprecated = (DiagnosticReporting)1u, bool useUnitTests = false, bool useInline = false, bool release = false, bool preservePaths = false, DiagnosticReporting warnings = (DiagnosticReporting)2u, bool cov = false, uint8_t covPercent = 0u, bool ctfe_cov = false, bool ignoreUnsupportedPragmas = true, bool useModuleInfo = true, bool useTypeInfo = true, bool useExceptions = true, bool useGC = true, bool betterC = false, bool addMain = false, bool allInst = false, bool bitfields = false, CppStdRevision cplusplus = (CppStdRevision)201103u, Help help = Help(), Verbose v = Verbose(), FeatureState useDIP25 = (FeatureState)2u, FeatureState useDIP1000 = (FeatureState)0u, bool ehnogc = false, bool useDIP1021 = false, FeatureState fieldwise = (FeatureState)0u, bool fixAliasThis = false, FeatureState rvalueRefParam = (FeatureState)0u, FeatureState noSharedAccess = (FeatureState)0u, bool previewIn = false, bool inclusiveInContracts = false, bool shortenedMethods = true, bool fixImmutableConv = false, bool fix16997 = true, FeatureState dtorFields = (FeatureState)0u, FeatureState systemVariables = (FeatureState)0u, bool privateThis = false, CHECKENABLE useInvariants = (CHECKENABLE)0u, CHECKENABLE useIn = (CHECKENABLE)0u, CHECKENABLE useOut = (CHECKENABLE)0u, CHECKENABLE useArrayBounds = (CHECKENABLE)0u, CHECKENABLE useAssert = (CHECKENABLE)0u, CHECKENABLE useSwitchError = (CHECKENABLE)0u, CHECKENABLE boundscheck = (CHECKENABLE)0u, CHECKACTION checkAction = (CHECKACTION)0u, _d_dynamicArray< const char > argv0 = {}, Array<const char* > modFileAliasStrings = Array<const char* >(), Array<const char* >* imppath = nullptr, Array<const char* >* fileImppath = nullptr, _d_dynamicArray< const char > objdir = {}, _d_dynamicArray< const char > objname = {}, _d_dynamicArray< const char > libname = {}, Output ddoc = Output(), Output dihdr = Output(), Output cxxhdr = Output(), Output json = Output(), JsonFieldFlags jsonFieldFlags = (JsonFieldFlags)0u, Output makeDeps = Output(), Output mixinOut = Output(), Output moduleDeps = Output(), uint32_t debuglevel = 0u, uint32_t versionlevel = 0u, bool run = false, Array<const char* > runargs = Array<const char* >(), Array<const char* > cppswitches = Array<const char* >(), const char* cpp = nullptr, Array<const char* > objfiles = Array<const char* >(), Array<const char* > linkswitches = Array<const char* >(), Array<bool > linkswitchIsForCC = Array<bool >(), Array<const char* > libfiles = Array<const char* >(), Array<const char* > dllfiles = Array<const char* >(), _d_dynamicArray< const char > deffile = {}, _d_dynamicArray< const char > resfile = {}, _d_dynamicArray< const char > exefile = {}, _d_dynamicArray< const char > mapfile = {}) :
         obj(obj),
         multiobj(multiobj),
         trace(trace),
@@ -8351,6 +8354,7 @@ struct Param final
         fix16997(fix16997),
         dtorFields(dtorFields),
         systemVariables(systemVariables),
+        privateThis(privateThis),
         useInvariants(useInvariants),
         useIn(useIn),
         useOut(useOut),

compiler/src/dmd/globals.d

@@ -238,6 +238,7 @@ extern (C++) struct Param
     FeatureState dtorFields;     // destruct fields of partially constructed objects
                                  // https://issues.dlang.org/show_bug.cgi?id=14246
     FeatureState systemVariables; // limit access to variables marked @system from @safe code
+    bool privateThis;             // add `private(this)`, limiting access to this class/struct/union
 
     CHECKENABLE useInvariants  = CHECKENABLE._default;  // generate class invariant checks
     CHECKENABLE useIn          = CHECKENABLE._default;  // generate precondition checks

compiler/src/dmd/globals.h

@@ -220,6 +220,7 @@ struct Param
     FeatureState dtorFields;     // destruct fields of partially constructed objects
                                  // https://issues.dlang.org/show_bug.cgi?id=14246
     FeatureState systemVariables; // limit access to variables marked @system from @safe code
+    d_bool privateThis;   // add `private(this)`, limiting access to this class/struct/union
 
     CHECKENABLE useInvariants;     // generate class invariant checks
     CHECKENABLE useIn;             // generate precondition checks

compiler/src/dmd/hdrgen.d

@@ -3306,9 +3306,10 @@ extern (D) string visibilityToString(Visibility.Kind kind) nothrow pure @safe
 {
     with (Visibility.Kind)
     {
-        immutable string[7] a = [
+        immutable string[8] a = [
                 none       : "none",
                 private_   : "private",
+                privateThis: "private(this)",
                 package_   : "package",
                 protected_ : "protected",
                 public_    : "public",

compiler/src/dmd/parse.d

@@ -50,6 +50,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
     }
 
     bool transitionIn = false; /// `-transition=in` is active, `in` parameters are listed
+    bool allowPrivateThis = true;
 
     /*********************
      * Use this constructor for string mixins.
@@ -857,7 +858,22 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
                 }
 
             case TOK.private_:
-                prot = AST.Visibility.Kind.private_;
+                if (peekNext() == TOK.leftParenthesis && peekNext2() == TOK.this_)
+                {
+                    if (!allowPrivateThis)
+                    {
+                        error("use `-preview=privateThis` to enable usage of `private(this)`");
+                    }
+                    nextToken();
+                    nextToken();
+                    nextToken();
+                    check(TOK.rightParenthesis);
+                    prot = AST.Visibility.Kind.privateThis;
+                }
+                else
+                {
+                    prot = AST.Visibility.Kind.private_;
+                }
                 goto Lprot;
 
             case TOK.package_:
@@ -887,7 +903,8 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
                     pAttrs.visibility.kind = prot;
                     const attrloc = token.loc;
 
-                    nextToken();
+                    if (pAttrs.visibility.kind != AST.Visibility.Kind.privateThis)
+                        nextToken();
 
                     // optional qualified package identifier to bind
                     // visibility to

compiler/src/dmd/statementsem.d

@@ -4999,6 +4999,7 @@ private Statements* flatten(Statement statement, Scope* sc)
             auto loc = adjustLocForMixin(str, cs.loc, global.params.mixinOut);
             scope p = new Parser!ASTCodegen(loc, sc._module, str, false, global.errorSink, &global.compileEnv, doUnittests);
             p.transitionIn = global.params.v.vin;
+            p.allowPrivateThis = global.params.privateThis;
             p.nextToken();
 
             auto a = new Statements();

compiler/src/dmd/tocvdebug.d

@@ -68,6 +68,7 @@ uint visibilityToCVAttr(Visibility.Kind vis) pure nothrow @safe @nogc
 
     final switch (vis)
     {
+        case Visibility.Kind.privateThis:
         case Visibility.Kind.private_:       attribute = 1;  break;
         case Visibility.Kind.package_:       attribute = 2;  break;
         case Visibility.Kind.protected_:     attribute = 2;  break;

compiler/src/dmd/typesem.d

@@ -6046,6 +6046,7 @@ RootObject compileTypeMixin(TypeMixin tm, ref const Loc loc, Scope* sc)
     auto locm = adjustLocForMixin(str, loc, global.params.mixinOut);
     scope p = new Parser!ASTCodegen(locm, sc._module, str, false, global.errorSink, &global.compileEnv, doUnittests);
     p.transitionIn = global.params.v.vin;
+    p.allowPrivateThis = global.params.privateThis;
     p.nextToken();
     //printf("p.loc.linnum = %d\n", p.loc.linnum);