diff --git a/src/dmd/backend/cgcod.d b/src/dmd/backend/cgcod.d
index 1d0bc86c89fe..f1f538c80dff 100644
--- a/src/dmd/backend/cgcod.d
+++ b/src/dmd/backend/cgcod.d
@@ -173,7 +173,7 @@ version (SCPP)
     allregs = ALLREGS;
     pass = PASSinitial;
     Alloca.init();
-    anyiasm = 0;
+    anyiasm = false;
 
     if (config.ehmethod == EHmethod.EH_DWARF)
     {
@@ -246,7 +246,7 @@ else version (SCPP)
         if (b.Belem)
             resetEcomsub(b.Belem);     // reset all the Ecomsubs
         if (b.BC == BCasm)
-            anyiasm = 1;                // we have inline assembler
+            anyiasm = true;                // we have inline assembler
         if (b.BC == BCret || b.BC == BCretexp)
             nretblocks++;
     }
diff --git a/src/dmd/backend/cgelem.d b/src/dmd/backend/cgelem.d
index 63c289249faf..a739f03dbda0 100644
--- a/src/dmd/backend/cgelem.d
+++ b/src/dmd/backend/cgelem.d
@@ -859,7 +859,7 @@ L1:
   else if (e2.Eoper == OPneg)
   {     e.EV.E2 = el_selecte1(e2);
         e.Eoper = OPmin;
-        again = 1;
+        again = true;
         return e;
   }
   /* Replace (-v + e) with (e + -v)     */
@@ -902,7 +902,7 @@ L1:
                 e.EV.E1.Ety = e1.Ety;
             }
         }
-        again = 1;
+        again = true;
         return e;
   }
   /* Replace (e + e) with (e * 2)       */
@@ -911,7 +911,7 @@ L1:
         e.Eoper = OPmul;
         el_free(e2);
         e.EV.E2 = el_long(e1.Ety,2);
-        again = 1;
+        again = true;
         return e;
   }
   // Replace ((e11 + c) + e2) with ((e11 + e2) + c)
@@ -999,7 +999,7 @@ private elem * elmul(elem *e, goal_t goal)
                     e1.Eoper = OPmul;
                     e.EV.E2 = el_bin(OPmul,tym,e1.EV.E2,e2);
                     e1.EV.E2 = el_copytree(e2);
-                    again = 1;
+                    again = true;
                     return e;
                 }
 
@@ -1008,7 +1008,7 @@ private elem * elmul(elem *e, goal_t goal)
                 {
                     e2.EV.Vullong *= cast(targ_ullong)1 << el_tolong(e1.EV.E2);
                     e1.EV.E2.EV.Vullong = 0;
-                    again = 1;
+                    again = true;
                     return e;
                 }
             }
@@ -1030,7 +1030,7 @@ private elem * elmul(elem *e, goal_t goal)
                 e2.Ety = TYint;
                 e.Eoper = (e.Eoper == OPmul)  /* convert to shift left */
                         ? OPshl : OPshlass;
-                again = 1;
+                again = true;
                 return e;
             }
             else if (el_allbits(e2,-1))
@@ -1048,7 +1048,7 @@ Lneg:
             ? OPneg : OPnegass;
     el_free(e.EV.E2);
     e.EV.E2 = null;
-    again = 1;
+    again = true;
     return e;
 }
 
@@ -3023,7 +3023,7 @@ private elem * elind(elem *e, goal_t goal)
             e.Ety = tym;
             e.EV.E2 = el_una(OPind,tym,e.EV.E2);
             e.EV.E2.ET = t;
-            again = 1;
+            again = true;
             return e;
 
         default:
@@ -3365,7 +3365,7 @@ elem * elstruct(elem *e, goal_t goal)
             if (e.Eoper == OPstreq)
             {   e.Eoper = OPcomma;
                 e = optelem(e,GOALvalue);
-                again = 1;
+                again = true;
             }
             else
                 goto Ldefault;
@@ -4534,7 +4534,7 @@ private elem * ellngsht(elem *e, goal_t goal)
             }
             e1.Ety = ty;
             e = el_selecte1(e);
-            again = 1;
+            again = true;
             return e;
         }
         break;
diff --git a/src/dmd/backend/cod2.d b/src/dmd/backend/cod2.d
index 08ca84fa09ff..5bfeb3e65dd5 100644
--- a/src/dmd/backend/cod2.d
+++ b/src/dmd/backend/cod2.d
@@ -557,7 +557,7 @@ else
             if (!rretregs)
                 rretregs = mLSW;
             rretregs |= mCX;
-            codelem(cdb,e1,&rretregs,0);
+            codelem(cdb,e1,&rretregs,false);
             retregs &= ~rretregs;
             if (!(retregs & mLSW))
                 retregs |= mLSW & ~rretregs;
@@ -566,7 +566,7 @@ else
         }
         else
         {   // long + hptr
-            codelem(cdb,e1,&retregs,0);
+            codelem(cdb,e1,&retregs,false);
             rretregs = (mLSW | mCX) & ~retregs;
             if (!(rretregs & mLSW))
                 rretregs |= mLSW;
diff --git a/src/dmd/backend/cod3.d b/src/dmd/backend/cod3.d
index 45a6101bf902..e454f94dfb91 100644
--- a/src/dmd/backend/cod3.d
+++ b/src/dmd/backend/cod3.d
@@ -834,7 +834,7 @@ void outblkexitcode(ref CodeBuilder cdb, block *bl, ref int anyspill, const(char
             {   // Swap bs1 and bs2
                 block *btmp;
 
-                jcond ^= 1;
+                jcond = !jcond;
                 btmp = bs1;
                 bs1 = bs2;
                 bs2 = btmp;
@@ -1376,7 +1376,7 @@ void doswitch(ref CodeBuilder cdb, block *b)
             if (n == 0)
                 msw = ms;
             else if (msw != ms)
-                mswsame = 0;
+                mswsame = false;
         }
         else // REGSIZE == 4
         {
@@ -1384,7 +1384,7 @@ void doswitch(ref CodeBuilder cdb, block *b)
             if (n == 0)
                 msw = ms;
             else if (msw != ms)
-                mswsame = 0;
+                mswsame = false;
         }
     }
     p -= ncases;
diff --git a/src/dmd/dcast.d b/src/dmd/dcast.d
index 3cfda5076d45..a2586356f340 100644
--- a/src/dmd/dcast.d
+++ b/src/dmd/dcast.d
@@ -335,6 +335,18 @@ MATCH implicitConvTo(Expression e, Type t)
             TY toty = t.toBasetype().ty;
             TY oldty = ty;
 
+            // DIP1015 - Stage 1 - Deprecation.  Remove this code when feature is removed.
+            if (m == MATCH.nomatch && t.ty == Tbool)
+                e.deprecation("cannot implicitly convert expression `%s` of type `%s` to `%s`",
+                        e.toChars(), e.type.toChars(), t.toChars());
+
+            // https://issues.dlang.org/show_bug.cgi?id=9999
+            // DIP1015 - Stage 2 - Removal - Uncomment when feature is removed, and uncomment
+            // code in test/runnable/test10560.d
+            // @@@DEPRECATED_[version]@@@
+            // if (m == MATCH.nomatch && t.ty == Tbool)
+            //     return;
+
             if (m == MATCH.nomatch && t.ty == Tenum)
                 return;
 
diff --git a/src/dmd/dinterpret.d b/src/dmd/dinterpret.d
index db58b768de8a..df466676b116 100644
--- a/src/dmd/dinterpret.d
+++ b/src/dmd/dinterpret.d
@@ -384,7 +384,7 @@ struct CompiledCtfeFunction
                 // Suppress the check in this case.
                 if (global.gag && ccf.func)
                 {
-                    stop = 1;
+                    stop = true;
                     return;
                 }
                 .error(e.loc, "CTFE internal error: ErrorExp in `%s`\n", ccf.func ? ccf.func.loc.toChars() : ccf.callingloc.toChars());
diff --git a/src/dmd/doc.d b/src/dmd/doc.d
index 0a7df87eddfa..b22caf4af175 100644
--- a/src/dmd/doc.d
+++ b/src/dmd/doc.d
@@ -2642,7 +2642,7 @@ private void highlightCode3(Scope* sc, OutBuffer* buf, const(char)* p, const(cha
 private void highlightCode2(Scope* sc, Dsymbols* a, OutBuffer* buf, size_t offset)
 {
     uint errorsave = global.errors;
-    scope Lexer lex = new Lexer(null, cast(char*)buf.data, 0, buf.offset - 1, 0, 1);
+    scope Lexer lex = new Lexer(null, cast(char*)buf.data, 0, buf.offset - 1, false, true);
     OutBuffer res;
     const(char)* lastp = cast(char*)buf.data;
     //printf("highlightCode2('%.*s')\n", buf.offset - 1, buf.data);
diff --git a/src/dmd/dsymbolsem.d b/src/dmd/dsymbolsem.d
index 09345310fa7c..d66616c138b4 100644
--- a/src/dmd/dsymbolsem.d
+++ b/src/dmd/dsymbolsem.d
@@ -1200,7 +1200,7 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
                                 }
                                 else
                                 {
-                                    ne.onstack = 1;
+                                    ne.onstack = true;
                                     dsym.onstack = true;
                                 }
                             }
@@ -3264,7 +3264,7 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
                 else
                 {
                     //printf("\tintroducing function %s\n", toChars());
-                    funcdecl.introducing = 1;
+                    funcdecl.introducing = true;
                     if (cd.classKind == ClassKind.cpp && Target.reverseCppOverloads)
                     {
                         // with dmc, overloaded functions are grouped and in reverse order
diff --git a/src/dmd/dtemplate.d b/src/dmd/dtemplate.d
index 613737f62866..a6d39cca29b0 100644
--- a/src/dmd/dtemplate.d
+++ b/src/dmd/dtemplate.d
@@ -2177,7 +2177,7 @@ extern (C++) final class TemplateDeclaration : ScopeDsymbol
             }
             tf.next = tret;
             if (ad && ad.isStructDeclaration())
-                tf.isref = 1;
+                tf.isref = true;
             //printf("tf = %s\n", tf.toChars());
         }
         else
@@ -6908,7 +6908,7 @@ extern (C++) class TemplateInstance : ScopeDsymbol
         if (semanticTiargs(loc, sc, tiargs, 0))
         {
             // cache the result iff semantic analysis succeeded entirely
-            semantictiargsdone = 1;
+            semantictiargsdone = true;
             return true;
         }
         return false;
diff --git a/src/dmd/errors.d b/src/dmd/errors.d
index 1c9dd8ddae39..c018ef7a2bae 100644
--- a/src/dmd/errors.d
+++ b/src/dmd/errors.d
@@ -492,7 +492,7 @@ private void colorHighlightCode(OutBuffer* buf)
     ++nested;
 
     auto gaggedErrorsSave = global.startGagging();
-    scope Lexer lex = new Lexer(null, cast(char*)buf.data, 0, buf.offset - 1, 0, 1);
+    scope Lexer lex = new Lexer(null, cast(char*)buf.data, 0, buf.offset - 1, false, true);
     OutBuffer res;
     const(char)* lastp = cast(char*)buf.data;
     //printf("colorHighlightCode('%.*s')\n", buf.offset - 1, buf.data);
diff --git a/src/dmd/glue.d b/src/dmd/glue.d
index 56d7bb78d8ca..74b4197f66eb 100644
--- a/src/dmd/glue.d
+++ b/src/dmd/glue.d
@@ -942,7 +942,7 @@ void FuncDeclaration_toObjFile(FuncDeclaration fd, bool multiobj)
         // Register return style cannot make nrvo.
         // Auto functions keep the nrvo_can flag up to here,
         // so we should eliminate it before entering backend.
-        fd.nrvo_can = 0;
+        fd.nrvo_can = false;
     }
 
     if (fd.vthis)
diff --git a/src/dmd/hdrgen.d b/src/dmd/hdrgen.d
index ef0fef36b18c..e28d8dd90337 100644
--- a/src/dmd/hdrgen.d
+++ b/src/dmd/hdrgen.d
@@ -68,7 +68,7 @@ enum TEST_EMIT_ALL = 0;
 extern (C++) void genhdrfile(Module m)
 {
     OutBuffer buf;
-    buf.doindent = 1;
+    buf.doindent = true;
     buf.printf("// D import file generated from '%s'", m.srcfile.toChars());
     buf.writenl();
     HdrGenState hgs;
diff --git a/src/dmd/lexer.d b/src/dmd/lexer.d
index cea93c999697..921647daff4c 100644
--- a/src/dmd/lexer.d
+++ b/src/dmd/lexer.d
@@ -146,7 +146,7 @@ unittest
     /* Not much here, just trying things out.
      */
     string text = "int"; // We rely on the implicit null-terminator
-    scope Lexer lex1 = new Lexer(null, text.ptr, 0, text.length, 0, 0);
+    scope Lexer lex1 = new Lexer(null, text.ptr, 0, text.length, false, false);
     TOK tok;
     tok = lex1.nextToken();
     //printf("tok == %s, %d, %d\n", Token::toChars(tok), tok, TOK.int32);
@@ -181,7 +181,7 @@ unittest
 
     foreach (testcase; testcases)
     {
-        scope Lexer lex2 = new Lexer(null, testcase.ptr, 0, testcase.length-1, 0, 0);
+        scope Lexer lex2 = new Lexer(null, testcase.ptr, 0, testcase.length-1, false, false);
         TOK tok = lex2.nextToken();
         size_t iterations = 1;
         while ((tok != TOK.endOfFile) && (iterations++ < testcase.length))
@@ -497,7 +497,7 @@ class Lexer : ErrorHandler
                     Identifier id = Identifier.idPool(cast(char*)t.ptr, cast(uint)(p - t.ptr));
                     t.ident = id;
                     t.value = cast(TOK)id.getValue();
-                    anyToken = 1;
+                    anyToken = true;
                     if (*t.ptr == '_') // if special identifier token
                     {
                         __gshared bool initdone = false;
diff --git a/src/dmd/mars.d b/src/dmd/mars.d
index fbbe363e3e49..04e99a829f2b 100644
--- a/src/dmd/mars.d
+++ b/src/dmd/mars.d
@@ -789,9 +789,9 @@ private int tryMain(size_t argc, const(char)** argv)
         foreach (mod; modules)
         {
             auto buf = OutBuffer();
-            buf.doindent = 1;
+            buf.doindent = true;
             scope HdrGenState hgs;
-            hgs.fullDump = 1;
+            hgs.fullDump = true;
             scope PrettyPrintVisitor ppv = new PrettyPrintVisitor(&buf, &hgs);
             mod.accept(ppv);
 
@@ -1555,7 +1555,7 @@ private bool parseCommandLine(const ref Strings arguments, const size_t argc, re
         {
             static if (TARGET.Linux || TARGET.OSX || TARGET.FreeBSD || TARGET.OpenBSD || TARGET.Solaris || TARGET.DragonFlyBSD)
             {
-                params.pic = 1;
+                params.pic = true;
             }
             else
             {
diff --git a/src/dmd/mtype.d b/src/dmd/mtype.d
index ac9655ff80cf..6f6e94a1a22d 100644
--- a/src/dmd/mtype.d
+++ b/src/dmd/mtype.d
@@ -2191,7 +2191,7 @@ extern (C++) abstract class Type : RootObject
 
     bool isBaseOf(Type t, int* poffset)
     {
-        return 0; // assume not
+        return false; // assume not
     }
 
     /********************************
diff --git a/src/dmd/objc.d b/src/dmd/objc.d
index a812697ef941..74f8c7e83efa 100644
--- a/src/dmd/objc.d
+++ b/src/dmd/objc.d
@@ -418,7 +418,7 @@ extern(C++) private final class Supported : Objc
         {
             auto members = new Dsymbols();
             members.push(classDeclaration);
-            return new ClassDeclaration(loc, Id.Class, metaBases, members, 0);
+            return new ClassDeclaration(loc, Id.Class, metaBases, members, false);
         }
 
         .setMetaclass!newMetaclass(classDeclaration);
diff --git a/src/dmd/parse.d b/src/dmd/parse.d
index 76936616d9b3..c8ed9bb7e3d1 100644
--- a/src/dmd/parse.d
+++ b/src/dmd/parse.d
@@ -1188,7 +1188,7 @@ final class Parser(AST) : Lexer
             {
                 auto a2 = new AST.Dsymbols();
                 a2.push(v);
-                auto tempdecl = new AST.TemplateDeclaration(loc, ident, tpl, null, a2, 0);
+                auto tempdecl = new AST.TemplateDeclaration(loc, ident, tpl, null, a2, false);
                 s = tempdecl;
             }
             a.push(s);
@@ -4696,7 +4696,7 @@ final class Parser(AST) : Lexer
                 {
                     auto a2 = new AST.Dsymbols();
                     a2.push(s);
-                    auto tempdecl = new AST.TemplateDeclaration(loc, ident, tpl, null, a2, 0);
+                    auto tempdecl = new AST.TemplateDeclaration(loc, ident, tpl, null, a2, false);
                     s = tempdecl;
                 }
                 if (setAlignment)
diff --git a/src/dmd/semantic3.d b/src/dmd/semantic3.d
index 06caddbb2714..33d64030da8c 100644
--- a/src/dmd/semantic3.d
+++ b/src/dmd/semantic3.d
@@ -559,12 +559,12 @@ private extern(C++) final class Semantic3Visitor : Visitor
                     sc2.ctorflow.allocFieldinit(ad2.fields.dim);
                     foreach (v; ad2.fields)
                     {
-                        v.ctorinit = 0;
+                        v.ctorinit = false;
                     }
                 }
 
                 if (!funcdecl.inferRetType && !Target.isReturnOnStack(f, funcdecl.needThis()))
-                    funcdecl.nrvo_can = 0;
+                    funcdecl.nrvo_can = false;
 
                 bool inferRef = (f.isref && (funcdecl.storage_class & STC.auto_));
 
@@ -618,7 +618,7 @@ private extern(C++) final class Semantic3Visitor : Visitor
                         funcdecl.storage_class &= ~STC.auto_;
                 }
                 if (!Target.isReturnOnStack(f, funcdecl.needThis()))
-                    funcdecl.nrvo_can = 0;
+                    funcdecl.nrvo_can = false;
 
                 if (funcdecl.fbody.isErrorStatement())
                 {
diff --git a/src/dmd/statementsem.d b/src/dmd/statementsem.d
index 25c1b25588f6..eef325a03a42 100644
--- a/src/dmd/statementsem.d
+++ b/src/dmd/statementsem.d
@@ -3177,10 +3177,10 @@ else
                 {
                     // Function returns a reference
                     if (!inferRef)
-                        fd.nrvo_can = 0;
+                        fd.nrvo_can = false;
                 }
                 else if (!v || v.isOut() || v.isRef())
-                    fd.nrvo_can = 0;
+                    fd.nrvo_can = false;
                 else if (fd.nrvo_var is null)
                 {
                     if (!v.isDataseg() && !v.isParameter() && v.toParent2() == fd)
@@ -3189,18 +3189,18 @@ else
                         fd.nrvo_var = v;
                     }
                     else
-                        fd.nrvo_can = 0;
+                        fd.nrvo_can = false;
                 }
                 else if (fd.nrvo_var != v)
-                    fd.nrvo_can = 0;
+                    fd.nrvo_can = false;
             }
             else //if (!exp.isLvalue())    // keep NRVO-ability
-                fd.nrvo_can = 0;
+                fd.nrvo_can = false;
         }
         else
         {
             // handle NRVO
-            fd.nrvo_can = 0;
+            fd.nrvo_can = false;
 
             // infer return type
             if (fd.inferRetType)
diff --git a/test/compilable/test9999.d b/test/compilable/test9999.d
new file mode 100644
index 000000000000..2ce866ffc95a
--- /dev/null
+++ b/test/compilable/test9999.d
@@ -0,0 +1,14 @@
+// The purpose of this test is to ensure that the implementation of
+// DIP1015 does not break the following conditionals
+
+void main()
+{
+    if(1) { }
+    if(0) { }
+    assert(1);
+    assert(0);
+    static assert(1);
+    while(0) { }
+    while(1) { }
+    for(;1;) { }
+}
diff --git a/test/fail_compilation/test9999.d b/test/fail_compilation/test9999.d
new file mode 100644
index 000000000000..74233faede24
--- /dev/null
+++ b/test/fail_compilation/test9999.d
@@ -0,0 +1,44 @@
+/*
+REQUIRED_ARGS: -de
+
+TEST_OUTPUT:
+---
+fail_compilation/test9999.d(27): Deprecation: cannot implicitly convert expression `'\x00'` of type `char` to `bool`
+fail_compilation/test9999.d(28): Deprecation: cannot implicitly convert expression `'\x01'` of type `char` to `bool`
+fail_compilation/test9999.d(30): Deprecation: cannot implicitly convert expression `'\x00'` of type `wchar` to `bool`
+fail_compilation/test9999.d(31): Deprecation: cannot implicitly convert expression `'\x01'` of type `wchar` to `bool`
+fail_compilation/test9999.d(33): Deprecation: cannot implicitly convert expression `0` of type `int` to `bool`
+fail_compilation/test9999.d(34): Deprecation: cannot implicitly convert expression `1` of type `int` to `bool`
+fail_compilation/test9999.d(36): Deprecation: cannot implicitly convert expression `0u` of type `uint` to `bool`
+fail_compilation/test9999.d(37): Deprecation: cannot implicitly convert expression `1u` of type `uint` to `bool`
+fail_compilation/test9999.d(39): Deprecation: cannot implicitly convert expression `0L` of type `long` to `bool`
+fail_compilation/test9999.d(40): Deprecation: cannot implicitly convert expression `1L` of type `long` to `bool`
+fail_compilation/test9999.d(42): Deprecation: cannot implicitly convert expression `0LU` of type `ulong` to `bool`
+fail_compilation/test9999.d(43): Deprecation: cannot implicitly convert expression `1LU` of type `ulong` to `bool`
+---
+*/
+
+// https://issues.dlang.org/show_bug.cgi?id=9999
+
+void main()
+{
+    bool boolValue;
+
+    boolValue = '\0';
+    boolValue = '\1';
+
+    boolValue = '\u0000';
+    boolValue = '\u0001';
+
+    boolValue = 0;
+    boolValue = 1;
+
+    boolValue = 0u;
+    boolValue = 1u;
+
+    boolValue = 0L;
+    boolValue = 1L;
+
+    boolValue = 0UL;
+    boolValue = 1UL;
+}
diff --git a/test/fail_compilation/warn7444.d b/test/fail_compilation/warn7444.d
index ec7d49c150b5..5afe89326b56 100644
--- a/test/fail_compilation/warn7444.d
+++ b/test/fail_compilation/warn7444.d
@@ -57,7 +57,7 @@ No warning
 void test10214()
 {
     bool[1] arr;
-    arr = 0;
+    arr = false;
     pragma(msg, "No warning");
 }
 
diff --git a/test/runnable/test10560.d b/test/runnable/test10560.d
new file mode 100644
index 000000000000..7a75af10ce8a
--- /dev/null
+++ b/test/runnable/test10560.d
@@ -0,0 +1,21 @@
+// https://issues.dlang.org/show_bug.cgi?id=10560
+
+// After the deprecation period for DIP 1015 has expired,
+// uncomment everything below.
+
+// int f(bool b) { return 1; }
+// int f(int i) { return 2; }
+
+// enum E : int
+// {
+//     a = 0,
+//     b = 1,
+//     c = 2,
+// }
+
+void main()
+{
+    // assert(f(E.a) == 2);
+    // assert(f(E.b) == 2);
+    // assert(f(E.c) == 2);
+}