Merge pull request #6816 from WalterBright/fix14246

fix Issue 14246 - RAII - proper destruction of partially constructed …
merged-on-behalf-of: Andrei Alexandrescu <andralex@users.noreply.github.com>

src/ddmd/aggregate.d

@@ -97,6 +97,7 @@ extern (C++) abstract class AggregateDeclaration : ScopeDsymbol
 
     FuncDeclarations dtors; // Array of destructors
     FuncDeclaration dtor;   // aggregate destructor
+    FuncDeclaration fieldDtor;   // aggregate destructor for just the fields
 
     Expression getRTInfo;   // pointer to GC info generated by object.RTInfo(this)
 

src/ddmd/aggregate.h

@@ -115,6 +115,7 @@ class AggregateDeclaration : public ScopeDsymbol
 
     FuncDeclarations dtors;     // Array of destructors
     FuncDeclaration *dtor;      // aggregate destructor
+    FuncDeclaration *fieldDtor; // aggregate destructor for just the fields
 
     Expression *getRTInfo;      // pointer to GC info generated by object.RTInfo(this)
 

src/ddmd/clone.d

@@ -1081,6 +1081,7 @@ extern (C++) FuncDeclaration buildDtor(AggregateDeclaration ad, Scope* sc)
         ad.dtors.shift(dd);
         ad.members.push(dd);
         dd.semantic(sc);
+        ad.fieldDtor = dd;
     }
 
     FuncDeclaration xdtor = null;

src/ddmd/func.d

@@ -1102,7 +1102,7 @@ extern (C++) class FuncDeclaration : Declaration
     }
 
     // Do the semantic analysis on the internals of the function.
-    override final void semantic3(Scope* sc)
+    override void semantic3(Scope* sc)
     {
         VarDeclaration _arguments = null;
 
@@ -4691,6 +4691,35 @@ extern (C++) final class CtorDeclaration : FuncDeclaration
         }
     }
 
+    override final void semantic3(Scope* sc)
+    {
+        if (semanticRun >= PASSsemantic3)
+            return;
+
+        /* If any of the fields of the struct have a destructor, add
+         *   scope (failure) { this.fieldDtor(); }
+         * as the first statement. It is not necessary to add it after
+         * each initialization of a field, because destruction of .init constructed
+         * structs should be benign.
+         */
+        AggregateDeclaration ad = toParent2().isAggregateDeclaration();
+        if (ad && ad.fieldDtor)
+        {
+            /* Generate:
+             *   scope (failure) { this.fieldDtor(); }
+             */
+            Expression e = new ThisExp(loc);
+            e.type = ad.type.mutableOf();
+            e = new DotVarExp(loc, e, ad.fieldDtor, false);
+            e = new CallExp(loc, e);
+            auto sexp = new ExpStatement(loc, e);
+            auto s = new OnScopeStatement(loc, TOKon_scope_failure, sexp);
+
+            fbody = new CompoundStatement(loc, s, fbody);
+        }
+        FuncDeclaration.semantic3(sc);
+    }
+
     override const(char)* kind() const
     {
         return "constructor";

test/runnable/sdtor.d

@@ -4222,6 +4222,38 @@ int test14860()
 }
 static assert(test14860());
 
+/**********************************/
+// https://issues.dlang.org/show_bug.cgi?id=14246
+
+struct A14246 {
+     int a = 3;
+     static string s;
+     this( int var ) { printf("A()\n"); a += var; s ~= "a"; }
+
+     ~this() { printf("~A()\n"); s ~= "b"; }
+}
+
+struct B14246 {
+     int i;
+     A14246 a;
+
+     this( int var ) {
+         A14246.s ~= "c";
+         a = A14246(var+1);
+         throw new Exception("An exception");
+     }
+}
+
+void test14246() {
+    try {
+         auto b = B14246(2);
+    } catch( Exception ex ) {
+        printf("Caught ex\n");
+        A14246.s ~= "d";
+    }
+    assert(A14246.s == "cabd");
+}
+
 /**********************************/
 // 14696
 
@@ -4605,6 +4637,7 @@ int main()
     test14815();
     test16197();
     test14860();
+    test14246();
     test14696();
     test14838();
     test63();