d: Import dmd b8384668f, druntime e6caaab9, phobos 5ab9ad256 (v2.098.0-beta.1)

The D front-end is now itself written in D, in order to build GDC, you
will need a working GDC compiler (GCC version 9.1 or later).

GCC changes:

    - Add support for bootstrapping the D front-end.

These add the required components in order to have a D front-end written
in D itself.  Because the compiler front-end only depends on the core
runtime modules, only libdruntime is built for the bootstrap stages.

D front-end changes:

    - Import dmd v2.098.0-beta.1.

Druntime changes:

    - Import druntime v2.098.0-beta.1.

Phobos changes:

    - Import phobos v2.098.0-beta.1.

The jump from v2.076.1 to v2.098.0 covers nearly 4 years worth of
development on the D programming language and run-time libraries.

ChangeLog:

	* Makefile.def: Add bootstrap to libbacktrace, libphobos, zlib, and
	libatomic.
	* Makefile.in: Regenerate.
	* Makefile.tpl (POSTSTAGE1_HOST_EXPORTS): Fix command for GDC.
	(STAGE1_CONFIGURE_FLAGS): Add --with-libphobos-druntime-only if
	target-libphobos-bootstrap.
	(STAGE2_CONFIGURE_FLAGS): Likewise.
	* configure: Regenerate.
	* configure.ac: Add support for bootstrapping D front-end.

config/ChangeLog:

	* acx.m4 (ACX_PROG_GDC): New m4 function.

gcc/ChangeLog:

	* Makefile.in (GDC): New variable.
	(GDCFLAGS): New variable.
	* configure: Regenerate.
	* configure.ac: Add call to ACX_PROG_GDC.  Substitute GDCFLAGS.

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd b8384668f.
	* Make-lang.in (d-warn): Use strict warnings.
	(DMD_WARN_CXXFLAGS): Remove.
	(DMD_COMPILE): Remove.
	(CHECKING_DFLAGS): Define.
	(WARN_DFLAGS): Define.
	(ALL_DFLAGS): Define.
	(DCOMPILE.base): Define.
	(DCOMPILE): Define.
	(DPOSTCOMPILE): Define.
	(DLINKER): Define.
	(DLLINKER): Define.
	(D_FRONTEND_OBJS): Add new dmd front-end objects.
	(D_GENERATED_SRCS): Remove.
	(D_GENERATED_OBJS): Remove.
	(D_ALL_OBJS): Remove D_GENERATED_OBJS.
	(d21$(exeext)): Build using DLLINKER and -static-libphobos.
	(d.tags): Remove dmd/*.c and dmd/root/*.c.
	(d.mostlyclean): Remove D_GENERATED_SRCS, d/idgen$(build_exeext),
	d/impcnvgen$(build_exeext).
	(D_INCLUDES): Include $(srcdir)/d/dmd/res.
	(CFLAGS-d/id.o): Remove.
	(CFLAGS-d/impcnvtab.o): Remove.
	(d/%.o): Build using DCOMPILE and DPOSTCOMPILE.  Update dependencies
	from d/dmd/%.c to d/dmd/%.d.
	(d/idgen$(build_exeext)): Remove.
	(d/impcnvgen$(build_exeext)): Remove.
	(d/id.c): Remove.
	(d/id.h): Remove.
	(d/impcnvtab.c): Remove.
	(d/%.dmdgen.o): Remove.
	(D_SYSTEM_H): Remove.
	(d/idgen.dmdgen.o): Remove.
	(d/impcnvgen.dmdgen.o): Remove.
	* config-lang.in (boot_language): New variable.
	* d-attribs.cc: Include dmd/expression.h.
	* d-builtins.cc: Include d-frontend.h.
	(build_frontend_type): Update for new front-end interface.
	(d_eval_constant_expression): Likewise.
	(d_build_builtins_module): Likewise.
	(maybe_set_builtin_1): Likewise.
	(d_build_d_type_nodes): Likewise.
	* d-codegen.cc (d_decl_context): Likewise.
	(declaration_reference_p): Likewise.
	(declaration_type): Likewise.
	(parameter_reference_p): Likewise.
	(parameter_type): Likewise.
	(get_array_length): Likewise.
	(build_delegate_cst): Likewise.
	(build_typeof_null_value): Likewise.
	(identity_compare_p): Likewise.
	(lower_struct_comparison): Likewise.
	(build_filename_from_loc): Likewise.
	(build_assert_call): Remove LIBCALL_SWITCH_ERROR.
	(build_bounds_index_condition): Call LIBCALL_ARRAYBOUNDS_INDEXP on
	bounds error.
	(build_bounds_slice_condition): Call LIBCALL_ARRAYBOUNDS_SLICEP on
	bounds error.
	(array_bounds_check): Update for new front-end interface.
	(checkaction_trap_p): Handle CHECKACTION_context.
	(get_function_type): Update for new front-end interface.
	(d_build_call): Likewise.
	* d-compiler.cc: Remove include of dmd/scope.h.
	(Compiler::genCmain): Remove.
	(Compiler::paintAsType): Update for new front-end interface.
	(Compiler::onParseModule): Likewise.
	* d-convert.cc (convert_expr): Remove call to LIBCALL_ARRAYCAST.
	(convert_for_rvalue): Update for new front-end interface.
	(convert_for_assignment): Likewise.
	(convert_for_condition): Likewise.
	(d_array_convert): Likewise.
	* d-diagnostic.cc (error): Remove.
	(errorSupplemental): Remove.
	(warning): Remove.
	(warningSupplemental): Remove.
	(deprecation): Remove.
	(deprecationSupplemental): Remove.
	(message): Remove.
	(vtip): New.
	* d-frontend.cc (global): Remove.
	(Global::_init): Remove.
	(Global::startGagging): Remove.
	(Global::endGagging): Remove.
	(Global::increaseErrorCount): Remove.
	(Loc::Loc): Remove.
	(Loc::toChars): Remove.
	(Loc::equals): Remove.
	(isBuiltin): Update for new front-end interface.
	(eval_builtin): Likewise.
	(getTypeInfoType): Likewise.
	(inlineCopy): Remove.
	* d-incpath.cc: Include d-frontend.h.
	(add_globalpaths): Call d_gc_malloc to allocate Strings.
	(add_filepaths): Likewise.
	* d-lang.cc: Include dmd/id.h, dmd/root/file.h, d-frontend.h.  Remove
	include of dmd/mars.h, id.h.
	(entrypoint_module): Remove.
	(entrypoint_root_module): Remove.
	(deps_write_string): Update for new front-end interface.
	(deps_write): Likewise.
	(d_init_options): Call rt_init.  Remove setting global params that are
	default initialized by the front-end.
	(d_handle_option): Handle OPT_fcheckaction_, OPT_fdump_c___spec_,
	OPT_fdump_c___spec_verbose, OPT_fextern_std_, OPT_fpreview,
	OPT_revert, OPT_fsave_mixins_, and OPT_ftransition.
	(d_post_options): Propagate dip1021 and dip1000 preview flags to
	dip25, and flag_diagnostics_show_caret to printErrorContext.
	(d_add_entrypoint_module): Remove.
	(d_parse_file): Update for new front-end interface.
	(d_type_promotes_to): Likewise.
	(d_types_compatible_p): Likewise.
	* d-longdouble.cc (CTFloat::zero): Remove.
	(CTFloat::one): Remove.
	(CTFloat::minusone): Remove.
	(CTFloat::half): Remove.
	* d-system.h (POSIX): Remove.
	(realpath): Remove.
	(isalpha): Remove.
	(isalnum): Remove.
	(isdigit): Remove.
	(islower): Remove.
	(isprint): Remove.
	(isspace): Remove.
	(isupper): Remove.
	(isxdigit): Remove.
	(tolower): Remove.
	(_mkdir): Remove.
	(INT32_MAX): Remove.
	(INT32_MIN): Remove.
	(INT64_MIN): Remove.
	(UINT32_MAX): Remove.
	(UINT64_MAX): Remove.
	* d-target.cc: Include calls.h.
	(target): Remove.
	(define_float_constants): Remove initialization of snan.
	(Target::_init): Update for new front-end interface.
	(Target::isVectorTypeSupported): Likewise.
	(Target::isVectorOpSupported): Remove cases for unordered operators.
	(TargetCPP::typeMangle): Update for new front-end interface.
	(TargetCPP::parameterType): Likewise.
	(Target::systemLinkage): Likewise.
	(Target::isReturnOnStack): Likewise.
	(Target::isCalleeDestroyingArgs): Define.
	(Target::preferPassByRef): Define.
	* d-tree.h (d_add_entrypoint_module): Remove.
	* decl.cc (gcc_attribute_p): Update for new front-end interface.
	(apply_pragma_crt): Define.
	(DeclVisitor::visit(PragmaDeclaration *)): Handle pragmas
	crt_constructor and crt_destructor.
	(DeclVisitor::visit(TemplateDeclaration *)): Update for new front-end
	interface.
	(DeclVisitor::visit): Likewise.
	(DeclVisitor::finish_vtable): Likewise.
	(get_symbol_decl): Error if template has more than one nesting
	context.  Update for new front-end interface.
	(make_thunk): Update for new front-end interface.
	(get_vtable_decl): Likewise.
	* expr.cc (ExprVisitor::visit): Likewise.
	(build_return_dtor): Likewise.
	* imports.cc (ImportVisitor::visit): Likewise.
	* intrinsics.cc: Include dmd/expression.h.  Remove include of
	dmd/mangle.h.
	(maybe_set_intrinsic): Update for new front-end interface.
	* intrinsics.def (INTRINSIC_ROL): Update intrinsic signature.
	(INTRINSIC_ROR): Likewise.
	(INTRINSIC_ROR_TIARG): Likewise.
	(INTRINSIC_TOPREC): Likewise.
	(INTRINSIC_TOPRECL): Likewise.
	(INTRINSIC_TAN): Update intrinsic module and signature.
	(INTRINSIC_ISNAN): Likewise.
	(INTRINSIC_ISFINITE): Likewise.
	(INTRINSIC_COPYSIGN): Define intrinsic.
	(INTRINSIC_COPYSIGNI): Define intrinsic.
	(INTRINSIC_EXP): Update intrinsic module.
	(INTRINSIC_EXPM1): Likewise.
	(INTRINSIC_EXP2): Likewise.
	(INTRINSIC_LOG): Likewise.
	(INTRINSIC_LOG2): Likewise.
	(INTRINSIC_LOG10): Likewise.
	(INTRINSIC_POW): Likewise.
	(INTRINSIC_ROUND): Likewise.
	(INTRINSIC_FLOORF): Likewise.
	(INTRINSIC_FLOOR): Likewise.
	(INTRINSIC_FLOORL): Likewise.
	(INTRINSIC_CEILF): Likewise.
	(INTRINSIC_CEIL): Likewise.
	(INTRINSIC_CEILL): Likewise.
	(INTRINSIC_TRUNC): Likewise.
	(INTRINSIC_FMIN): Likewise.
	(INTRINSIC_FMAX): Likewise.
	(INTRINSIC_FMA): Likewise.
	(INTRINSIC_VA_ARG): Update intrinsic signature.
	(INTRINSIC_VASTART): Likewise.
	* lang.opt (fcheck=): Add alternate aliases for contract switches.
	(fcheckaction=): New option.
	(check_action): New Enum and EnumValue entries.
	(fdump-c++-spec-verbose): New option.
	(fdump-c++-spec=): New option.
	(fextern-std=): New option.
	(extern_stdcpp): New Enum and EnumValue entries
	(fpreview=): New options.
	(frevert=): New options.
	(fsave-mixins): New option.
	(ftransition=): Update options.
	* modules.cc (get_internal_fn): Replace Prot with Visibility.
	(build_internal_fn): Likewise.
	(build_dso_cdtor_fn): Likewise.
	(build_module_tree): Remove check for __entrypoint module.
	* runtime.def (P5): Define.
	(ARRAYBOUNDS_SLICEP): Define.
	(ARRAYBOUNDS_INDEXP): Define.
	(NEWTHROW): Define.
	(ADCMP2): Remove.
	(ARRAYCAST): Remove.
	(SWITCH_STRING): Remove.
	(SWITCH_USTRING): Remove.
	(SWITCH_DSTRING): Remove.
	(SWITCH_ERROR): Remove.
	* toir.cc (IRVisitor::visit): Update for new front-end interface.
	(IRVisitor::check_previous_goto): Remove checks for case and default
	statements.
	(IRVisitor::visit(SwitchStatement *)): Remove handling of string
	switch conditions.
	* typeinfo.cc: Include d-frontend.h.
	(get_typeinfo_kind): Update for new front-end interface.
	(make_frontend_typeinfo): Likewise.
	(TypeInfoVisitor::visit): Likewise.
	(builtin_typeinfo_p): Likewise.
	(get_typeinfo_decl): Likewise.
	(build_typeinfo): Likewise.
	* types.cc (valist_array_p): Likewise.
	(make_array_type): Likewise.
	(merge_aggregate_types): Likewise.
	(TypeVisitor::visit(TypeBasic *)): Likewise.
	(TypeVisitor::visit(TypeFunction *)): Likewise.
	(TypeVisitor::visit(TypeStruct *)): Update comment.
	* verstr.h: Removed.
	* d-frontend.h: New file.

gcc/po/ChangeLog:

	* EXCLUDES: Remove d/dmd sources from list.

gcc/testsuite/ChangeLog:

	* gdc.dg/Wcastresult2.d: Update test.
	* gdc.dg/asm1.d: Likewise.
	* gdc.dg/asm2.d: Likewise.
	* gdc.dg/asm3.d: Likewise.
	* gdc.dg/gdc282.d: Likewise.
	* gdc.dg/imports/gdc170.d: Likewise.
	* gdc.dg/intrinsics.d: Likewise.
	* gdc.dg/pr101672.d: Likewise.
	* gdc.dg/pr90650a.d: Likewise.
	* gdc.dg/pr90650b.d: Likewise.
	* gdc.dg/pr94777a.d: Likewise.
	* gdc.dg/pr95250.d: Likewise.
	* gdc.dg/pr96869.d: Likewise.
	* gdc.dg/pr98277.d: Likewise.
	* gdc.dg/pr98457.d: Likewise.
	* gdc.dg/simd1.d: Likewise.
	* gdc.dg/simd2a.d: Likewise.
	* gdc.dg/simd2b.d: Likewise.
	* gdc.dg/simd2c.d: Likewise.
	* gdc.dg/simd2d.d: Likewise.
	* gdc.dg/simd2e.d: Likewise.
	* gdc.dg/simd2f.d: Likewise.
	* gdc.dg/simd2g.d: Likewise.
	* gdc.dg/simd2h.d: Likewise.
	* gdc.dg/simd2i.d: Likewise.
	* gdc.dg/simd2j.d: Likewise.
	* gdc.dg/simd7951.d: Likewise.
	* gdc.dg/torture/gdc309.d: Likewise.
	* gdc.dg/torture/pr94424.d: Likewise.
	* gdc.dg/torture/pr94777b.d: Likewise.
	* lib/gdc-utils.exp (gdc-convert-args): Handle new compiler options.
	(gdc-convert-test): Handle CXXFLAGS, EXTRA_OBJC_SOURCES, and ARG_SETS
	test directives.
	(gdc-do-test): Only import modules in the test run directory.
	* gdc.dg/pr94777c.d: New test.
	* gdc.dg/pr96156b.d: New test.
	* gdc.dg/pr96157c.d: New test.
	* gdc.dg/simd_ctfe.d: New test.
	* gdc.dg/torture/simd17344.d: New test.
	* gdc.dg/torture/simd20052.d: New test.
	* gdc.dg/torture/simd6.d: New test.
	* gdc.dg/torture/simd7.d: New test.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime e6caaab9.
	* libdruntime/Makefile.am (D_EXTRA_FLAGS): Build libdruntime with
	-fpreview=dip1000, -fpreview=fieldwise, and -fpreview=dtorfields.
	(ALL_DRUNTIME_SOURCES): Add DRUNTIME_DSOURCES_STDCXX.
	(DRUNTIME_DSOURCES): Update list of C binding modules.
	(DRUNTIME_DSOURCES_STDCXX): Likewise.
	(DRUNTIME_DSOURCES_LINUX): Likewise.
	(DRUNTIME_DSOURCES_OPENBSD): Likewise.
	(DRUNTIME_DISOURCES): Remove __entrypoint.di.
	* libdruntime/Makefile.in: Regenerated.
	* libdruntime/__entrypoint.di: Removed.
	* libdruntime/gcc/deh.d (_d_isbaseof): Update signature.
	(_d_createTrace): Likewise.
	(__gdc_begin_catch): Remove reference to the exception.
	(_d_throw): Increment reference count of thrown object before unwind.
	(__gdc_personality): Chain exceptions with  Throwable.chainTogether.
	* libdruntime/gcc/emutls.d: Update imports.
	* libdruntime/gcc/sections/elf.d: Update imports.
	(DSO.moduleGroup): Update signature.
	* libdruntime/gcc/sections/macho.d: Update imports.
	(DSO.moduleGroup): Update signature.
	* libdruntime/gcc/sections/pecoff.d: Update imports.
	(DSO.moduleGroup): Update signature.
	* src/MERGE: Merge upstream phobos 5ab9ad256.
	* src/Makefile.am (D_EXTRA_DFLAGS): Add -fpreview=dip1000 and
	-fpreview=dtorfields flags.
	(PHOBOS_DSOURCES): Update list of std modules.
	* src/Makefile.in: Regenerate.
	* testsuite/lib/libphobos.exp (libphobos-dg-test): Handle assembly
	compile types.
	(dg-test): Override.
	(additional_prunes): Define.
	(libphobos-dg-prune): Filter any additional_prunes set by tests.
	* testsuite/libphobos.aa/test_aa.d: Update test.
	* testsuite/libphobos.druntime/druntime.exp (version_flags): Add
	-fversion=CoreUnittest.
	* testsuite/libphobos.druntime_shared/druntime_shared.exp
	(version_flags): Add -fversion=CoreUnittest -fversion=Shared.
	* testsuite/libphobos.exceptions/unknown_gc.d: Update test.
	* testsuite/libphobos.hash/test_hash.d: Update test.
	* testsuite/libphobos.phobos/phobos.exp (version_flags): Add
	-fversion=StdUnittest
	* testsuite/libphobos.phobos_shared/phobos_shared.exp (version_flags):
	Likewise.
	* testsuite/libphobos.shared/host.c: Update test.
	* testsuite/libphobos.shared/load.d: Update test.
	* testsuite/libphobos.shared/load_13414.d: Update test.
	* testsuite/libphobos.thread/fiber_guard_page.d: Update test.
	* testsuite/libphobos.thread/tlsgc_sections.d: Update test.
	* testsuite/testsuite_flags.in: Add -fpreview=dip1000 to --gdcflags.
	* testsuite/libphobos.shared/link_mod_collision.d: Removed.
	* testsuite/libphobos.shared/load_mod_collision.d: Removed.
	* testsuite/libphobos.betterc/betterc.exp: New test.
	* testsuite/libphobos.config/config.exp: New test.
	* testsuite/libphobos.gc/gc.exp: New test.
	* testsuite/libphobos.imports/imports.exp: New test.
	* testsuite/libphobos.lifetime/lifetime.exp: New test.
	* testsuite/libphobos.unittest/unittest.exp: New test.

1 files changed, 232 insertions, 142 deletions

diff --git a/libphobos/src/std/base64.d b/libphobos/src/std/base64.d
index 6211d10..866f700 100644
--- a/libphobos/src/std/base64.d
+++ b/libphobos/src/std/base64.d
@@ -51,15 +51,16 @@
  * Copyright: Masahiro Nakagawa 2010-.
  * License:   $(HTTP boost.org/LICENSE_1_0.txt, Boost License 1.0).
  * Authors:   Masahiro Nakagawa, Daniel Murphy (Single value Encoder and Decoder)
- * Source:    $(PHOBOSSRC std/_base64.d)
+ * Source:    $(PHOBOSSRC std/base64.d)
  * Macros:
- *      LREF2=<a href="#$1">$(D $2)</a>
+ *      LREF2=<a href="#$1">`$2`</a>
  */
 module std.base64;
 
-import std.exception;  // enforce
-import std.range.primitives;      // isInputRange, isOutputRange, isForwardRange, ElementType, hasLength
-import std.traits;     // isArray
+import std.exception : enforce;
+import std.range.primitives : empty, front, isInputRange, isOutputRange,
+    isForwardRange, ElementType, hasLength, popFront, put, save;
+import std.traits : isArray;
 
 // Make sure module header code examples work correctly.
 @safe unittest
@@ -138,8 +139,8 @@ alias Base64URLNoPadding = Base64Impl!('-', '_', Base64.NoPadding);
  * -----
  *
  * NOTE:
- * Encoded strings will not have any padding if the $(D Padding) parameter is
- * set to $(D NoPadding).
+ * Encoded strings will not have any padding if the `Padding` parameter is
+ * set to `NoPadding`.
  */
 template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 {
@@ -205,19 +206,19 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
 
     /**
-     * Encode $(D_PARAM source) into a $(D char[]) buffer using Base64
+     * Encode $(D_PARAM source) into a `char[]` buffer using Base64
      * encoding.
      *
      * Params:
-     *  source = The $(LINK2 std_range_primitives.html#isInputRange, input
-     *           range) to _encode.
-     *  buffer = The $(D char[]) buffer to store the encoded result.
+     *  source = The $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *           to _encode.
+     *  buffer = The `char[]` buffer to store the encoded result.
      *
      * Returns:
      *  The slice of $(D_PARAM buffer) that contains the encoded string.
      */
     @trusted
-    pure char[] encode(R1, R2)(in R1 source, R2 buffer) if (isArray!R1 && is(ElementType!R1 : ubyte) &&
+    pure char[] encode(R1, R2)(in R1 source, return scope R2 buffer) if (isArray!R1 && is(ElementType!R1 : ubyte) &&
                                                             is(R2 == char[]))
     in
     {
@@ -227,7 +228,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
     {
         assert(result.length == encodeLength(source.length), "The length of result is different from Base64");
     }
-    body
+    do
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -310,7 +311,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         // @@@BUG@@@ D's DbC can't caputre an argument of function and store the result of precondition.
         //assert(result.length == encodeLength(source.length), "The length of result is different from Base64");
     }
-    body
+    do
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -362,7 +363,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         }
 
         // @@@BUG@@@ Workaround for DbC problem. See comment on 'out'.
-        version (unittest)
+        version (StdUnittest)
             assert(
                 bufptr - buffer.ptr == encodeLength(srcLen),
                 "The length of result is different from Base64"
@@ -378,26 +379,25 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
     /**
      * Encodes $(D_PARAM source) into an
-     * $(LINK2 std_range_primitives.html#isOutputRange, output range) using
+     * $(REF_ALTTEXT output range, isOutputRange, std,range,primitives) using
      * Base64 encoding.
      *
      * Params:
-     *  source = The $(LINK2 std_range_primitives.html#isInputRange, input
-     *           range) to _encode.
-     *  range  = The $(LINK2 std_range_primitives.html#isOutputRange, output
-     *           range) to store the encoded result.
+     *  source = The $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *           to _encode.
+     *  range  = The $(REF_ALTTEXT output range, isOutputRange, std,range,primitives)
+     *           to store the encoded result.
      *
      * Returns:
-     *  The number of times the output range's $(D put) method was invoked.
+     *  The number of times the output range's `put` method was invoked.
      */
-    size_t encode(R1, R2)(in R1 source, auto ref R2 range)
-        if (isArray!R1 && is(ElementType!R1 : ubyte) &&
-            !is(R2 == char[]) && isOutputRange!(R2, char))
+    size_t encode(E, R)(scope const(E)[] source, auto ref R range)
+    if (is(E : ubyte) && isOutputRange!(R, char) && !is(R == char[]))
     out(result)
     {
         assert(result == encodeLength(source.length), "The number of put is different from the length of Base64");
     }
-    body
+    do
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -405,23 +405,23 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
         immutable blocks = srcLen / 3;
         immutable remain = srcLen % 3;
-        auto      srcptr = source.ptr;
-        size_t    pcount;
+        auto s = source; // copy for out contract length check
+        size_t pcount;
 
         foreach (Unused; 0 .. blocks)
         {
-            immutable val = srcptr[0] << 16 | srcptr[1] << 8 | srcptr[2];
+            immutable val = s[0] << 16 | s[1] << 8 | s[2];
             put(range, EncodeMap[val >> 18       ]);
             put(range, EncodeMap[val >> 12 & 0x3f]);
             put(range, EncodeMap[val >>  6 & 0x3f]);
             put(range, EncodeMap[val       & 0x3f]);
-            srcptr += 3;
+            s = s[3 .. $];
             pcount += 4;
         }
 
         if (remain)
         {
-            immutable val = srcptr[0] << 16 | (remain == 2 ? srcptr[1] << 8 : 0);
+            immutable val = s[0] << 16 | (remain == 2 ? s[1] << 8 : 0);
             put(range, EncodeMap[val >> 18       ]);
             put(range, EncodeMap[val >> 12 & 0x3f]);
             pcount += 2;
@@ -453,22 +453,17 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
     }
 
     ///
-    @system unittest
+    @safe pure nothrow unittest
     {
-        // @system because encode for OutputRange is @system
-        struct OutputRange
-        {
-            char[] result;
-            void put(const(char) ch) @safe { result ~= ch; }
-        }
+        import std.array : appender;
 
+        auto output = appender!string();
         ubyte[] data = [0x1a, 0x2b, 0x3c, 0x4d, 0x5d, 0x6e];
 
         // This overload of encode() returns the number of calls to the output
         // range's put method.
-        OutputRange output;
         assert(Base64.encode(data, output) == 8);
-        assert(output.result == "Gis8TV1u");
+        assert(output.data == "Gis8TV1u");
     }
 
 
@@ -481,12 +476,6 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
     size_t encode(R1, R2)(R1 source, auto ref R2 range)
         if (!isArray!R1 && isInputRange!R1 && is(ElementType!R1 : ubyte) &&
             hasLength!R1 && !is(R2 == char[]) && isOutputRange!(R2, char))
-    out(result)
-    {
-        // @@@BUG@@@ Workaround for DbC problem.
-        //assert(result == encodeLength(source.length), "The number of put is different from the length of Base64");
-    }
-    body
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -546,7 +535,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         }
 
         // @@@BUG@@@ Workaround for DbC problem.
-        version (unittest)
+        version (StdUnittest)
             assert(
                 pcount == encodeLength(srcLen),
                 "The number of put is different from the length of Base64"
@@ -563,11 +552,11 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
      * buffers.
      *
      * Params:
-     *  source = The $(LINK2 std_range_primitives.html#isInputRange, input
-     *           range) to _encode.
+     *  source = The $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *           to _encode.
      *
      * Returns:
-     *  A newly-allocated $(D char[]) buffer containing the encoded string.
+     *  A newly-allocated `char[]` buffer containing the encoded string.
      */
     @safe
     pure char[] encode(Range)(Range source) if (isArray!Range && is(ElementType!Range : ubyte))
@@ -594,12 +583,11 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
 
     /**
-     * An $(LINK2 std_range_primitives.html#isInputRange, input range) that
+     * An $(REF_ALTTEXT input range, isInputRange, std,range,primitives) that
      * iterates over the respective Base64 encodings of a range of data items.
      *
-     * This range will be a $(LINK2 std_range_primitives.html#isForwardRange,
-     * forward range) if the underlying data source is at least a forward
-     * range.
+     * This range will be a $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives)
+     * if the underlying data source is at least a forward range.
      *
      * Note: This struct is not intended to be created in user code directly;
      * use the $(LREF encoder) function instead.
@@ -616,7 +604,8 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         this(Range range)
         {
             range_ = range;
-            doEncoding();
+            if (!empty)
+                doEncoding();
         }
 
 
@@ -645,8 +634,8 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
          * Advance the range to the next chunk of encoded data.
          *
          * Throws:
-         *  $(D Base64Exception) If invoked when
-         *  $(LREF2 .Base64Impl.Encoder.empty, empty) returns $(D true).
+         *  `Base64Exception` If invoked when
+         *  $(LREF2 .Base64Impl.Encoder.empty, empty) returns `true`.
          */
         void popFront()
         {
@@ -671,11 +660,10 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
              * Save the current iteration state of the range.
              *
              * This method is only available if the underlying range is a
-             * $(LINK2 std_range_primitives.html#isForwardRange, forward
-             * range).
+             * $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives).
              *
              * Returns:
-             *  A copy of $(D this).
+             *  A copy of `this`.
              */
             @property
             typeof(this) save()
@@ -705,11 +693,11 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
 
     /**
-     * An $(LINK2 std_range_primitives.html#isInputRange, input range) that
+     * An $(REF_ALTTEXT input range, isInputRange, std,range,primitives) that
      * iterates over the encoded bytes of the given source data.
      *
-     * It will be a $(LINK2 std_range_primitives.html#isForwardRange, forward
-     * range) if the underlying data source is at least a forward range.
+     * It will be a $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives)
+     * if the underlying data source is at least a forward range.
      *
      * Note: This struct is not intended to be created in user code directly;
      * use the $(LREF encoder) function instead.
@@ -764,8 +752,8 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
          * Advance to the next encoded character.
          *
          * Throws:
-         *  $(D Base64Exception) If invoked when $(LREF2 .Base64Impl.Encoder.empty.2,
-         *  empty) returns $(D true).
+         *  `Base64Exception` If invoked when $(LREF2 .Base64Impl.Encoder.empty.2,
+         *  empty) returns `true`.
          */
         void popFront()
         {
@@ -835,11 +823,10 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
              * Save the current iteration state of the range.
              *
              * This method is only available if the underlying range is a
-             * $(LINK2 std_range_primitives.html#isForwardRange, forward
-             * range).
+             * $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives).
              *
              * Returns:
-             *  A copy of $(D this).
+             *  A copy of `this`.
              */
             @property
             typeof(this) save()
@@ -853,23 +840,23 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
 
     /**
-     * Construct an $(D Encoder) that iterates over the Base64 encoding of the
-     * given $(LINK2 std_range_primitives.html#isInputRange, input range).
+     * Construct an `Encoder` that iterates over the Base64 encoding of the
+     * given $(REF_ALTTEXT input range, isInputRange, std,range,primitives).
      *
      * Params:
-     *  range = An $(LINK2 std_range_primitives.html#isInputRange, input
-     *      range) over the data to be encoded.
+     *  range = An $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *          over the data to be encoded.
      *
      * Returns:
-     *  If $(D_PARAM range) is a range of bytes, an $(D Encoder) that iterates
+     *  If $(D_PARAM range) is a range of bytes, an `Encoder` that iterates
      *  over the bytes of the corresponding Base64 encoding.
      *
-     *  If $(D_PARAM range) is a range of ranges of bytes, an $(D Encoder) that
+     *  If $(D_PARAM range) is a range of ranges of bytes, an `Encoder` that
      *  iterates over the Base64 encoded strings of each element of the range.
      *
-     *  In both cases, the returned $(D Encoder) will be a
-     *  $(LINK2 std_range_primitives.html#isForwardRange, forward range) if the
-     *  given $(D range) is at least a forward range, otherwise it will be only
+     *  In both cases, the returned `Encoder` will be a
+     *  $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives) if the
+     *  given `range` is at least a forward range, otherwise it will be only
      *  an input range.
      *
      * Example:
@@ -982,19 +969,19 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
      * Decodes $(D_PARAM source) into the given buffer.
      *
      * Params:
-     *  source = The $(LINK2 std_range_primitives.html#isInputRange, input
-     *      range) to _decode.
+     *  source = The $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *           to _decode.
      *  buffer = The buffer to store decoded result.
      *
      * Returns:
      *  The slice of $(D_PARAM buffer) containing the decoded result.
      *
      * Throws:
-     *  $(D Base64Exception) if $(D_PARAM source) contains characters outside the
+     *  `Base64Exception` if $(D_PARAM source) contains characters outside the
      *  base alphabet of the current Base64 encoding scheme.
      */
     @trusted
-    pure ubyte[] decode(R1, R2)(in R1 source, R2 buffer) if (isArray!R1 && is(ElementType!R1 : dchar) &&
+    pure ubyte[] decode(R1, R2)(in R1 source, return scope R2 buffer) if (isArray!R1 && is(ElementType!R1 : dchar) &&
                                                              is(R2 == ubyte[]) && isOutputRange!(R2, ubyte))
     in
     {
@@ -1005,7 +992,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         immutable expect = realDecodeLength(source);
         assert(result.length == expect, "The length of result is different from the expected length");
     }
-    body
+    do
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -1085,13 +1072,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
     {
         assert(buffer.length >= decodeLength(source.length), "Insufficient buffer for decoding");
     }
-    out(result)
-    {
-        // @@@BUG@@@ Workaround for DbC problem.
-        //immutable expect = decodeLength(source.length) - 2;
-        //assert(result.length >= expect, "The length of result is smaller than expected length");
-    }
-    body
+    do
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -1143,8 +1124,8 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
             }
         }
 
-        // @@@BUG@@@ Workaround for DbC problem.
-        version (unittest)
+        // We need to do the check here because we have consumed the length
+        version (StdUnittest)
             assert(
                 (bufptr - buffer.ptr) >= (decodeLength(srcLen) - 2),
                 "The length of result is smaller than expected length"
@@ -1159,19 +1140,19 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
     /**
      * Decodes $(D_PARAM source) into a given
-     * $(LINK2 std_range_primitives.html#isOutputRange, output range).
+     * $(REF_ALTTEXT output range, isOutputRange, std,range,primitives).
      *
      * Params:
-     *  source = The $(LINK2 std_range_primitives.html#isInputRange, input
-     *           range) to _decode.
-     *  range  = The $(LINK2 std_range_primitives.html#isOutputRange, output
-     *           range) to store the decoded result.
+     *  source = The $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *           to _decode.
+     *  range  = The $(REF_ALTTEXT output range, isOutputRange, std,range,primitives)
+     *           to store the decoded result.
      *
      * Returns:
-     *  The number of times the output range's $(D put) method was invoked.
+     *  The number of times the output range's `put` method was invoked.
      *
      * Throws:
-     *  $(D Base64Exception) if $(D_PARAM source) contains characters outside the
+     *  `Base64Exception` if $(D_PARAM source) contains characters outside the
      *  base alphabet of the current Base64 encoding scheme.
      */
     size_t decode(R1, R2)(in R1 source, auto ref R2 range)
@@ -1182,7 +1163,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         immutable expect = realDecodeLength(source);
         assert(result == expect, "The result of decode is different from the expected");
     }
-    body
+    do
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -1271,7 +1252,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         //immutable expect = decodeLength(source.length) - 2;
         //assert(result >= expect, "The length of result is smaller than expected length");
     }
-    body
+    do
     {
         immutable srcLen = source.length;
         if (srcLen == 0)
@@ -1329,7 +1310,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         }
 
         // @@@BUG@@@ Workaround for DbC problem.
-        version (unittest)
+        version (StdUnittest)
             assert(
                 pcount >= (decodeLength(srcLen) - 2),
                 "The length of result is smaller than expected length"
@@ -1346,11 +1327,11 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
      * buffers.
      *
      * Params:
-     *  source = The $(LINK2 std_range_primitives.html#isInputRange, input
-     *           range) to _decode.
+     *  source = The $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *           to _decode.
      *
      * Returns:
-     *  A newly-allocated $(D ubyte[]) buffer containing the decoded string.
+     *  A newly-allocated `ubyte[]` buffer containing the decoded string.
      */
     @safe
     pure ubyte[] decode(Range)(Range source) if (isArray!Range && is(ElementType!Range : dchar))
@@ -1377,12 +1358,11 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
 
     /**
-     * An $(LINK2 std_range_primitives.html#isInputRange, input range) that
+     * An $(REF_ALTTEXT input range, isInputRange, std,range,primitives) that
      * iterates over the decoded data of a range of Base64 encodings.
      *
-     * This range will be a $(LINK2 std_range_primitives.html#isForwardRange,
-     * forward range) if the underlying data source is at least a forward
-     * range.
+     * This range will be a $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives)
+     * if the underlying data source is at least a forward range.
      *
      * Note: This struct is not intended to be created in user code directly;
      * use the $(LREF decoder) function instead.
@@ -1399,7 +1379,8 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         this(Range range)
         {
             range_ = range;
-            doDecoding();
+            if (!empty)
+                doDecoding();
         }
 
 
@@ -1428,8 +1409,8 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
          * Advance to the next element in the input to be decoded.
          *
          * Throws:
-         *  $(D Base64Exception) if invoked when $(LREF2 .Base64Impl.Decoder.empty,
-         *  empty) returns $(D true).
+         *  `Base64Exception` if invoked when $(LREF2 .Base64Impl.Decoder.empty,
+         *  empty) returns `true`.
          */
         void popFront()
         {
@@ -1451,10 +1432,9 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
              * Saves the current iteration state.
              *
              * This method is only available if the underlying range is a
-             * $(LINK2 std_range_primitives.html#isForwardRange, forward
-             * range).
+             * $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives)
              *
-             * Returns: A copy of $(D this).
+             * Returns: A copy of `this`.
              */
             @property
             typeof(this) save()
@@ -1488,6 +1468,7 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
                 while (data.length % 4 != 0)
                 {
                     range_.popFront();
+                    enforce(!range_.empty, new Base64Exception("Invalid length of encoded data"));
                     data ~= cast(const(char)[])range_.front;
                 }
             }
@@ -1502,12 +1483,11 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
 
     /**
-     * An $(LINK2 std_range_primitives.html#isInputRange, input range) that
+     * An $(REF_ALTTEXT input range, isInputRange, std,range,primitives) that
      * iterates over the bytes of data decoded from a Base64 encoded string.
      *
-     * This range will be a $(LINK2 std_range_primitives.html#isForwardRange,
-     * forward range) if the underlying data source is at least a forward
-     * range.
+     * This range will be a $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives)
+     * if the underlying data source is at least a forward range.
      *
      * Note: This struct is not intended to be created in user code directly;
      * use the $(LREF decoder) function instead.
@@ -1562,8 +1542,8 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
          * Advance to the next decoded byte.
          *
          * Throws:
-         *  $(D Base64Exception) if invoked when $(LREF2 .Base64Impl.Decoder.empty,
-         *  empty) returns $(D true).
+         *  `Base64Exception` if invoked when $(LREF2 .Base64Impl.Decoder.empty,
+         *  empty) returns `true`.
          */
         void popFront()
         {
@@ -1644,10 +1624,9 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
              * Saves the current iteration state.
              *
              * This method is only available if the underlying range is a
-             * $(LINK2 std_range_primitives.html#isForwardRange, forward
-             * range).
+             * $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives)
              *
-             * Returns: A copy of $(D this).
+             * Returns: A copy of `this`.
              */
             @property
             typeof(this) save()
@@ -1661,31 +1640,30 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
 
 
     /**
-     * Construct a $(D Decoder) that iterates over the decoding of the given
+     * Construct a `Decoder` that iterates over the decoding of the given
      * Base64 encoded data.
      *
      * Params:
-     *  range = An $(LINK2 std_range_primitives.html#isInputRange, input
-     *      range) over the data to be decoded.
+     *  range = An $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+     *      over the data to be decoded, or a `char` array. Will not accept
+     *      `wchar[]` nor `dchar[]`.
      *
      * Returns:
-     *  If $(D_PARAM range) is a range of characters, a $(D Decoder) that
+     *  If $(D_PARAM range) is a range or array of `char`, a `Decoder` that
      *  iterates over the bytes of the corresponding Base64 decoding.
      *
-     *  If $(D_PARAM range) is a range of ranges of characters, a $(D Decoder)
+     *  If $(D_PARAM range) is a range of ranges of characters, a `Decoder`
      *  that iterates over the decoded strings corresponding to each element of
-     *  the range. In this case, the length of each subrange must be a multiple
-     *  of 4; the returned _decoder does not keep track of Base64 decoding
-     *  state across subrange boundaries.
+     *  the range.
      *
-     *  In both cases, the returned $(D Decoder) will be a
-     *  $(LINK2 std_range_primitives.html#isForwardRange, forward range) if the
-     *  given $(D range) is at least a forward range, otherwise it will be only
+     *  In both cases, the returned `Decoder` will be a
+     *  $(REF_ALTTEXT forward range, isForwardRange, std,range,primitives) if the
+     *  given `range` is at least a forward range, otherwise it will be only
      *  an input range.
      *
      * If the input data contains characters not found in the base alphabet of
      * the current Base64 encoding scheme, the returned range may throw a
-     * $(D Base64Exception).
+     * `Base64Exception`.
      *
      * Example:
      * This example shows decoding over a range of input data lines.
@@ -1696,7 +1674,6 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
      * }
      * -----
      *
-     * Example:
      * This example shows decoding one byte at a time.
      * -----
      * auto encoded = Base64.encoder(cast(ubyte[])"0123456789");
@@ -1711,6 +1688,24 @@ template Base64Impl(char Map62th, char Map63th, char Padding = '=')
         return typeof(return)(range);
     }
 
+    /// ditto
+    Decoder!(const(ubyte)[]) decoder()(const(char)[] range)
+    {
+        import std.string : representation;
+        return typeof(return)(range.representation);
+    }
+
+    ///
+    @safe pure unittest
+    {
+        import std.algorithm.comparison : equal;
+        string encoded =
+            "VGhvdSBzaGFsdCBuZXZlciBjb250aW51ZSBhZnRlciBhc3NlcnRpbmcgbnVsbA==";
+
+        assert(Base64.decoder(encoded)
+            .equal("Thou shalt never continue after asserting null"));
+    }
+
 
   private:
     @safe
@@ -1766,18 +1761,18 @@ class Base64Exception : Exception
 }
 
 ///
-@system unittest
+@safe unittest
 {
     import std.exception : assertThrown;
     assertThrown!Base64Exception(Base64.decode("ab|c"));
 }
 
-
 @system unittest
 {
     import std.algorithm.comparison : equal;
     import std.algorithm.sorting : sort;
     import std.conv;
+    import std.exception : assertThrown;
     import std.file;
     import std.stdio;
 
@@ -1920,7 +1915,8 @@ class Base64Exception : Exception
         assert(tv["foobar"] == b.data); a.clear(); b.clear();
     }
 
-    // @@@9543@@@ These tests were disabled because they actually relied on the input range having length.
+    // https://issues.dlang.org/show_bug.cgi?id=9543
+    // These tests were disabled because they actually relied on the input range having length.
     // The implementation (currently) doesn't support encoding/decoding from a length-less source.
     version (none)
     { // with InputRange
@@ -2039,7 +2035,7 @@ class Base64Exception : Exception
 }
 
 // Regression control for the output range ref bug in encode.
-@system unittest
+@safe unittest
 {
     struct InputRange
     {
@@ -2064,12 +2060,14 @@ class Base64Exception : Exception
     // Verify that any existing workaround that uses & still works.
     InputRange ir2;
     OutputRange or2;
-    assert(Base64.encode(ir2, &or2) == 8);
+    () @trusted {
+        assert(Base64.encode(ir2, &or2) == 8);
+    }();
     assert(or2.result == "Gis8TV1u");
 }
 
 // Regression control for the output range ref bug in decode.
-@system unittest
+@safe unittest
 {
     struct InputRange
     {
@@ -2094,6 +2092,98 @@ class Base64Exception : Exception
     // Verify that any existing workaround that uses & still works.
     InputRange ir2;
     OutputRange or2;
-    assert(Base64.decode(ir2, &or2) == 6);
+    () @trusted {
+        assert(Base64.decode(ir2, &or2) == 6);
+    }();
     assert(or2.result == [0x1a, 0x2b, 0x3c, 0x4d, 0x5d, 0x6e]);
 }
+
+// https://issues.dlang.org/show_bug.cgi?id=21679
+// https://issues.dlang.org/show_bug.cgi?id=21706
+@safe unittest
+{
+    ubyte[][] input;
+    assert(Base64.encoder(input).empty);
+    assert(Base64.decoder(input).empty);
+}
+
+@safe unittest
+{
+    struct InputRange(ubyte[] data)
+    {
+        ubyte[] impl = data;
+        bool empty() { return impl.length == 0; }
+        ubyte front() { return impl[0]; }
+        void popFront() { impl = impl[1 .. $]; }
+        size_t length() { return impl.length; }
+    }
+
+    struct OutputRange
+    {
+        ubyte[] result;
+        void put(ubyte b) { result ~= b; }
+    }
+
+    void test_encode(ubyte[] data, string result)()
+    {
+        InputRange!data ir;
+        OutputRange or;
+        assert(Base64.encode(ir, or) == result.length);
+        assert(or.result == result);
+    }
+
+    void test_decode(ubyte[] data, string result)()
+    {
+        InputRange!data ir;
+        OutputRange or;
+        assert(Base64.decode(ir, or) == result.length);
+        assert(or.result == result);
+    }
+
+    test_encode!([], "");
+    test_encode!(['x'], "eA==");
+    test_encode!([123, 45], "ey0=");
+
+    test_decode!([], "");
+    test_decode!(['e', 'A', '=', '='], "x");
+    test_decode!(['e', 'y', '0', '='], "{-");
+}
+
+@system unittest
+{
+    // checking forward range
+    auto item = Base64.decoder(Base64.encoder(cast(ubyte[]) "foobar"));
+    auto copy = item.save();
+    item.popFront();
+    assert(item.front == 'o');
+    assert(copy.front == 'f');
+}
+
+@system unittest
+{
+    // checking invalid dchar
+    dchar[] c = cast(dchar[]) "ääää";
+
+    import std.exception : assertThrown;
+    assertThrown!Base64Exception(Base64.decode(c));
+}
+
+@safe unittest
+{
+    import std.array : array;
+
+    char[][] input = [['e', 'y'], ['0', '=']];
+    assert(Base64.decoder(input).array == [[123, 45]]);
+}
+
+// https://issues.dlang.org/show_bug.cgi?id=21707
+@safe unittest
+{
+    import std.exception : assertThrown;
+
+    char[][] t1 = [[ 'Z', 'g', '=' ]];
+    assertThrown!Base64Exception(Base64.decoder(t1));
+
+    char[][] t2 = [[ 'e', 'y', '0' ], ['=', '=']];
+    assertThrown!Base64Exception(Base64.decoder(t2));
+}