diff --git a/src/dmd/dmodule.d b/src/dmd/dmodule.d
index aa7a6b422041..7170447a3092 100644
--- a/src/dmd/dmodule.d
+++ b/src/dmd/dmodule.d
@@ -943,7 +943,7 @@ extern (C++) final class Module : Package
             assert(prev);
             if (Module mprev = prev.isModule())
             {
-                if (FileName.compare(srcname, mprev.srcfile.toChars()) != 0)
+                if (!FileName.equals(srcname, mprev.srcfile.toChars()))
                     error(loc, "from file %s conflicts with another module %s from file %s", srcname, mprev.toChars(), mprev.srcfile.toChars());
                 else if (isRoot() && mprev.isRoot())
                     error(loc, "from file %s is specified twice on the command line", srcname);
diff --git a/src/dmd/dmsc.d b/src/dmd/dmsc.d
index 61265fb2418a..d632fce84489 100644
--- a/src/dmd/dmsc.d
+++ b/src/dmd/dmsc.d
@@ -98,7 +98,7 @@ void backend_init()
             exe = true;         // EXE file only optimizations
         else if (params.exefile)           // if writing out EXE file
         {   size_t len = strlen(params.exefile);
-            if (len >= 4 && FileName.compare(params.exefile + len - 3, "exe") == 0)
+            if (len >= 4 && FileName.equals(params.exefile + len - 3, "exe"))
                 exe = true;
         }
     }
diff --git a/src/dmd/dsymbolsem.d b/src/dmd/dsymbolsem.d
index 72e96f5a4294..5b9386b57c6e 100644
--- a/src/dmd/dsymbolsem.d
+++ b/src/dmd/dsymbolsem.d
@@ -1533,13 +1533,12 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
             else
                 ob.writestring("???");
             ob.writeByte(')');
-            for (size_t i = 0; i < imp.names.dim; i++)
+            foreach (i, name; imp.names)
             {
                 if (i == 0)
                     ob.writeByte(':');
                 else
                     ob.writeByte(',');
-                Identifier name = imp.names[i];
                 Identifier _alias = imp.aliases[i];
                 if (!_alias)
                 {
diff --git a/src/dmd/mars.d b/src/dmd/mars.d
index c737ad4d35c9..976bec522b37 100644
--- a/src/dmd/mars.d
+++ b/src/dmd/mars.d
@@ -878,11 +878,8 @@ private int tryMain(size_t argc, const(char)** argv)
         library = Library.factory();
         library.setFilename(global.params.objdir, global.params.libname);
         // Add input object and input library files to output library
-        for (size_t i = 0; i < libmodules.dim; i++)
-        {
-            const(char)* p = libmodules[i];
+        foreach (p; libmodules)
             library.addObject(p, null);
-        }
     }
     // Generate output files
     if (global.params.doJsonGeneration)
@@ -2243,8 +2240,8 @@ private bool parseCommandLine(const ref Strings arguments, const size_t argc, re
         {
             static if (TARGET.Windows)
             {
-                const(char)* ext = FileName.ext(p);
-                if (ext && FileName.compare(ext, "exe") == 0)
+                const ext = FileName.ext(p);
+                if (ext && FileName.equals(ext, "exe"))
                 {
                     params.objname = p;
                     continue;
diff --git a/src/dmd/root/file.d b/src/dmd/root/file.d
index c86cb3e94585..24ae49ec619d 100644
--- a/src/dmd/root/file.d
+++ b/src/dmd/root/file.d
@@ -194,8 +194,6 @@ nothrow:
         }
         else version (Windows)
         {
-            import dmd.root.filename: extendedPathThen;
-
             DWORD size;
             DWORD numread;
 
@@ -272,8 +270,6 @@ nothrow:
         }
         else version (Windows)
         {
-            import dmd.root.filename: extendedPathThen;
-
             DWORD numwritten; // here because of the gotos
             const(char)* name = this.name.toChars();
             // work around Windows file path length limitation
diff --git a/src/dmd/root/filename.d b/src/dmd/root/filename.d
index 34450e037e2a..61af71c09af2 100644
--- a/src/dmd/root/filename.d
+++ b/src/dmd/root/filename.d
@@ -21,12 +21,13 @@ import core.sys.windows.windows;
 import dmd.root.array;
 import dmd.root.file;
 import dmd.root.outbuffer;
+import dmd.root.port;
 import dmd.root.rmem;
 import dmd.root.rootobject;
+import dmd.utils;
 
 nothrow
 {
-version (Windows) extern (C) int stricmp(const char*, const char*) pure;
 version (Windows) extern (Windows) DWORD GetFullPathNameW(LPCWSTR, DWORD, LPWSTR, LPWSTR*) @nogc;
 version (Windows) extern (Windows) void SetLastError(DWORD) @nogc;
 version (Windows) extern (C) char* getcwd(char* buffer, size_t maxlen);
@@ -49,30 +50,25 @@ nothrow:
         this.str = mem.xstrdup(str);
     }
 
-    extern (C++) bool equals(const RootObject obj) const pure
-    {
-        return compare(obj) == 0;
-    }
-
+    /// Compare two name according to the platform's rules (case sensitive or not)
     extern (C++) static bool equals(const(char)* name1, const(char)* name2) pure
     {
-        return compare(name1, name2) == 0;
+        return equals(name1.toDString, name2.toDString);
     }
 
-    extern (C++) int compare(const RootObject obj) const pure
+    /// Ditto
+    extern (D) static bool equals(const(char)[] name1, const(char)[] name2) pure
     {
-        return compare(str, (cast(FileName*)obj).str);
-    }
+        if (name1.length != name2.length)
+            return false;
 
-    extern (C++) static int compare(const(char)* name1, const(char)* name2) pure
-    {
         version (Windows)
         {
-            return stricmp(name1, name2);
+            return Port.memicmp(name1.ptr, name2.ptr, name1.length) == 0;
         }
         else
         {
-            return strcmp(name1, name2);
+            return name1 == name2;
         }
     }
 
@@ -299,39 +295,66 @@ nothrow:
         return f;
     }
 
+    /**
+       Combine a `path` and a file `name`
+
+       Params:
+         path = Path to append to
+         name = Name to append to path
+
+       Returns:
+         The `\0` terminated string which is the combination of `path` and `name`
+         and a valid path.
+    */
     extern (C++) static const(char)* combine(const(char)* path, const(char)* name)
     {
-        char* f;
-        size_t pathlen;
-        size_t namelen;
-        if (!path || !*path)
-            return cast(char*)name;
-        pathlen = strlen(path);
-        namelen = strlen(name);
-        f = cast(char*)mem.xmalloc(pathlen + 1 + namelen + 1);
-        memcpy(f, path, pathlen);
+        if (!path)
+            return name;
+        return combine(path.toDString, name.toDString).ptr;
+    }
+
+    /// Ditto
+    extern(D) static const(char)[] combine(const(char)[] path, const(char)[] name)
+    {
+        if (!path.length)
+            return name;
+
+        char* f = cast(char*)mem.xmalloc(path.length + 1 + name.length + 1);
+        memcpy(f, path.ptr, path.length);
+        bool trailingSlash = false;
         version (Posix)
         {
-            if (path[pathlen - 1] != '/')
+            if (path[$ - 1] != '/')
             {
-                f[pathlen] = '/';
-                pathlen++;
+                f[path.length] = '/';
+                trailingSlash = true;
             }
         }
         else version (Windows)
         {
-            if (path[pathlen - 1] != '\\' && path[pathlen - 1] != '/' && path[pathlen - 1] != ':')
+            if (path[$ - 1] != '\\' && path[$ - 1] != '/' && path[$ - 1] != ':')
             {
-                f[pathlen] = '\\';
-                pathlen++;
+                f[path.length] = '\\';
+                trailingSlash = true;
             }
         }
         else
         {
             assert(0);
         }
-        memcpy(f + pathlen, name, namelen + 1);
-        return f;
+        const len = path.length + trailingSlash;
+        memcpy(f + len, name.ptr, name.length);
+        // Note: At the moment `const(char)*` are being transitioned to
+        // `const(char)[]`. To avoid bugs crippling in, we `\0` terminate
+        // slices, but don't include it in the slice so `.ptr` can be used.
+        f[len + name.length] = '\0';
+        return f[0 .. len + name.length];
+    }
+
+    unittest
+    {
+        assert(combine("foo"[], "bar"[]) == "foo/bar");
+        assert(combine("foo/"[], "bar"[]) == "foo/bar");
     }
 
     static const(char)* buildPath(const(char)* path, const(char)*[] names...)
@@ -469,7 +492,7 @@ nothrow:
             return true;
         if (!e || !ext)
             return false;
-        return FileName.compare(e, ext) == 0;
+        return FileName.equals(e, ext);
     }
 
     /******************************
diff --git a/src/dmd/root/filename.h b/src/dmd/root/filename.h
index e43313c439e4..c4b0089004f4 100644
--- a/src/dmd/root/filename.h
+++ b/src/dmd/root/filename.h
@@ -25,10 +25,7 @@ struct FileName
 {
     const char *str;
     FileName(const char *str);
-    bool equals(RootObject *obj);
     static bool equals(const char *name1, const char *name2);
-    int compare(RootObject *obj);
-    static int compare(const char *name1, const char *name2);
     static bool absolute(const char *name);
     static const char *toAbsolute(const char *name, const char *base = NULL);
     static const char *ext(const char *);
diff --git a/src/dmd/root/outbuffer.d b/src/dmd/root/outbuffer.d
index 1695f889e45d..dc61cf6510ec 100644
--- a/src/dmd/root/outbuffer.d
+++ b/src/dmd/root/outbuffer.d
@@ -85,11 +85,6 @@ struct OutBuffer
         offset += nbytes;
     }
 
-    extern (C++) void writebstring(char* string) nothrow
-    {
-        write(string, *string + 1);
-    }
-
     extern (C++) void writestring(const(char)* string) nothrow
     {
         write(string, strlen(string));
diff --git a/src/dmd/root/outbuffer.h b/src/dmd/root/outbuffer.h
index f5b3f27d2187..c9413acb4665 100644
--- a/src/dmd/root/outbuffer.h
+++ b/src/dmd/root/outbuffer.h
@@ -55,7 +55,6 @@ struct OutBuffer
     void setsize(size_t size);
     void reset();
     void write(const void *data, d_size_t nbytes);
-    void writebstring(utf8_t *string);
     void writestring(const char *string);
     void prependstring(const char *string);
     void writenl();                     // write newline
diff --git a/src/dmd/root/port.d b/src/dmd/root/port.d
index a4b03c63a3a5..1b893a1b218d 100644
--- a/src/dmd/root/port.d
+++ b/src/dmd/root/port.d
@@ -18,6 +18,8 @@ import core.stdc.string;
 import core.stdc.stdio;
 import core.stdc.stdlib;
 
+nothrow @nogc:
+
 private extern (C)
 {
     version(CRuntime_DigitalMars) __gshared extern const(char)* __locale_decpoint;
@@ -34,7 +36,9 @@ private extern (C)
 
 extern (C++) struct Port
 {
-    static int memicmp(const char* s1, const char* s2, size_t n)
+    nothrow @nogc:
+
+    static int memicmp(scope const char* s1, scope const char* s2, size_t n) pure
     {
         int result = 0;
 
@@ -54,7 +58,7 @@ extern (C++) struct Port
         return result;
     }
 
-    static char* strupr(char* s)
+    static char* strupr(char* s) pure
     {
         char* t = s;
 
@@ -67,7 +71,7 @@ extern (C++) struct Port
         return t;
     }
 
-    static bool isFloat32LiteralOutOfRange(const(char)* s)
+    static bool isFloat32LiteralOutOfRange(scope const(char)* s)
     {
         errno = 0;
         version (CRuntime_DigitalMars)
@@ -90,7 +94,7 @@ extern (C++) struct Port
         return errno == ERANGE;
     }
 
-    static bool isFloat64LiteralOutOfRange(const(char)* s)
+    static bool isFloat64LiteralOutOfRange(scope const(char)* s)
     {
         errno = 0;
         version (CRuntime_DigitalMars)
@@ -114,7 +118,7 @@ extern (C++) struct Port
     }
 
     // Little endian
-    static void writelongLE(uint value, void* buffer)
+    static void writelongLE(uint value, scope void* buffer) pure
     {
         auto p = cast(ubyte*)buffer;
         p[3] = cast(ubyte)(value >> 24);
@@ -124,14 +128,14 @@ extern (C++) struct Port
     }
 
     // Little endian
-    static uint readlongLE(void* buffer)
+    static uint readlongLE(scope void* buffer) pure
     {
         auto p = cast(ubyte*)buffer;
         return (((((p[3] << 8) | p[2]) << 8) | p[1]) << 8) | p[0];
     }
 
     // Big endian
-    static void writelongBE(uint value, void* buffer)
+    static void writelongBE(uint value, scope void* buffer) pure
     {
         auto p = cast(ubyte*)buffer;
         p[0] = cast(ubyte)(value >> 24);
@@ -141,27 +145,27 @@ extern (C++) struct Port
     }
 
     // Big endian
-    static uint readlongBE(void* buffer)
+    static uint readlongBE(scope void* buffer) pure
     {
         auto p = cast(ubyte*)buffer;
         return (((((p[0] << 8) | p[1]) << 8) | p[2]) << 8) | p[3];
     }
 
     // Little endian
-    static uint readwordLE(void* buffer)
+    static uint readwordLE(scope void* buffer) pure
     {
         auto p = cast(ubyte*)buffer;
         return (p[1] << 8) | p[0];
     }
 
     // Big endian
-    static uint readwordBE(void* buffer)
+    static uint readwordBE(scope void* buffer) pure
     {
         auto p = cast(ubyte*)buffer;
         return (p[0] << 8) | p[1];
     }
 
-    static void valcpy(void *dst, ulong val, size_t size)
+    static void valcpy(scope void *dst, ulong val, size_t size) pure
     {
         switch (size)
         {
diff --git a/src/dmd/root/stringtable.d b/src/dmd/root/stringtable.d
index c18496ef0361..2d9b1876c018 100644
--- a/src/dmd/root/stringtable.d
+++ b/src/dmd/root/stringtable.d
@@ -57,6 +57,12 @@ pure:
     {
         return cast(const(char)*)(&this + 1);
     }
+
+    /// Returns: The content of this entry as a D slice
+    extern (D) inout(char)[] toString() inout
+    {
+        return (cast(inout(char)*)(&this + 1))[0 .. length];
+    }
 }
 
 struct StringTable
diff --git a/src/dmd/utils.d b/src/dmd/utils.d
index bb6edab6ae6b..d02550cd02b5 100644
--- a/src/dmd/utils.d
+++ b/src/dmd/utils.d
@@ -21,6 +21,7 @@ import dmd.globals;
 import dmd.root.file;
 import dmd.root.filename;
 import dmd.root.outbuffer;
+import dmd.root.rmem;
 
 
 /**
@@ -170,3 +171,45 @@ extern(D) static bool iequals(const(char)[] s1, const(char)[] s2)
     }
     return true;
 }
+
+/**
+Copy the content of `src` into a C-string ('\0' terminated) then call `dg`
+
+The intent of this function is to provide an allocation-less
+way to call a C function using a D slice.
+The function internally allocates a buffer if needed, but frees it on exit.
+
+Note:
+The argument to `dg` is `scope`. To keep the data around after `dg` exits,
+one has to copy it.
+
+Params:
+src = Slice to use to call the C function
+dg  = Delegate to call afterwards
+
+Returns:
+The return value of `T`
+*/
+auto toCStringThen(alias dg)(const(char)[] src) nothrow
+{
+    const len = src.length + 1;
+    char[512] small = void;
+    scope ptr = (src.length < (small.length - 1))
+                    ? small[0 .. len]
+                    : (cast(char*)mem.xmalloc(len))[0 .. len];
+    scope (exit)
+    {
+        if (&ptr[0] != &small[0])
+            mem.xfree(&ptr[0]);
+    }
+    ptr[0 .. src.length] = src[];
+    ptr[src.length] = '\0';
+    return dg(ptr);
+}
+
+unittest
+{
+    assert("Hello world".toCStringThen!((v) => v == "Hello world\0"));
+    assert("Hello world\0".toCStringThen!((v) => v == "Hello world\0\0"));
+    assert(null.toCStringThen!((v) => v == "\0"));
+}
diff --git a/src/posix.mak b/src/posix.mak
index 570e0c2283e7..2c1ae2220e70 100644
--- a/src/posix.mak
+++ b/src/posix.mak
@@ -473,7 +473,7 @@ unittest: $G/dmd-unittest
 ######## DMD as a library examples
 
 EXAMPLES=$(addprefix $G/examples/, avg impvisitor)
-PARSER_SRCS=$(addsuffix .d, $(addprefix $D/,parse astbase parsetimevisitor transitivevisitor permissivevisitor strictvisitor))
+PARSER_SRCS=$(addsuffix .d, $(addprefix $D/,parse astbase parsetimevisitor transitivevisitor permissivevisitor strictvisitor utils))
 
 $G/parser.a: $(PARSER_SRCS) $(LEXER_SRCS) $(ROOT_SRCS) $G/dmd $G/dmd.conf $(SRC_MAKE)
 	CC="$(HOST_CXX)" $G/dmd -lib -of$@ $(MODEL_FLAG) -L-lstdc++ -J$G $(DFLAGS) $(PARSER_SRCS) $(LEXER_SRCS) $(ROOT_SRCS)
diff --git a/src/win32.mak b/src/win32.mak
index 1eeeb4a43408..ece7dacffa9f 100644
--- a/src/win32.mak
+++ b/src/win32.mak
@@ -172,7 +172,7 @@ LEXER_ROOT=$(ROOT)/array.d $(ROOT)/ctfloat.d $(ROOT)/file.d $(ROOT)/filename.d \
 	$(ROOT)/outbuffer.d $(ROOT)/port.d $(ROOT)/rmem.d $(ROOT)/rootobject.d \
 	$(ROOT)/stringtable.d $(ROOT)/hash.d
 
-PARSER_SRCS=$D/astbase.d $D/parsetimevisitor.d $D/parse.d $D/transitivevisitor.d $D/permissivevisitor.d $D/strictvisitor.d
+PARSER_SRCS=$D/astbase.d $D/parsetimevisitor.d $D/parse.d $D/transitivevisitor.d $D/permissivevisitor.d $D/strictvisitor.d $D/utils.d
 
 GLUE_SRCS=$D/irstate.d $D/toctype.d $D/glue.d $D/gluelayer.d $D/todt.d $D/tocsym.d $D/toir.d $D/dmsc.d \
 	$D/tocvdebug.d $D/s2ir.d $D/toobj.d $D/e2ir.d $D/objc_glue.d $D/eh.d $D/iasm.d $D/iasmdmd.d $D/iasmgcc.d