Merge branch 'master' into gfortran-testdevel/gfortran-test

23 files changed, 648 insertions, 171 deletions

diff --git a/gcc/m2/ChangeLog b/gcc/m2/ChangeLog
index 6babeb9..f63381d 100644
--- a/gcc/m2/ChangeLog
+++ b/gcc/m2/ChangeLog
@@ -1,3 +1,97 @@
+2025-08-29  Gaius Mulley  <gaiusmod2@gmail.com>
+
+	PR modula2/121709
+	* gm2-lang.cc (concat_component): New function.
+	(find_cpp_entry): Ditto.
+	(lookup_cpp_default): Ditto.
+	(add_default_include_paths): Rewrite.
+	(m2_pathname_root): Remove.
+
+2025-08-28  Gaius Mulley  <gaiusmod2@gmail.com>
+
+	PR modula2/121629
+	* gm2-compiler/PathName.mod: Add copyright notice.
+	* gm2-lang.cc (named_path): Add field lib_root.
+	(push_back_Ipath): Set lib_root false.
+	(push_back_lib_root): New function.
+	(get_dir_sep_size): Ditto.
+	(add_path_component): Ditto.
+	(add_one_import_path): Ditto.
+	(add_non_dialect_specific_path): Ditto.
+	(foreach_lib_gen_import_path): Ditto.
+	(get_module_source_dir): Ditto.
+	(add_default_include_paths): Ditto.
+	(assign_flibs): Ditto.
+	(m2_pathname_root): Ditto.
+	(add_m2_import_paths): Remove function.
+	(gm2_langhook_post_options): Call assign_flibs.
+	Check np.lib_root and call foreach_lib_gen_import_path.
+	Replace call to add_m2_import_paths with a call to
+	add_default_include_paths.
+	(gm2_langhook_handle_option): Add case OPT_fm2_pathname_rootI_.
+	* gm2spec.cc (named_path): Add field lib_root.
+	(push_back_Ipath): Set lib_root false.
+	(push_back_lib_root): New function.
+	(add_m2_I_path): Add OPT_fm2_pathname_rootI_ option
+	if np.lib_root.
+	(lang_specific_driver): Add case OPT_fm2_pathname_root_.
+	* lang.opt (fm2-pathname-root=): New option.
+	(fm2-pathname-rootI=): Ditto.
+
+2025-08-01  Gaius Mulley  <gaiusmod2@gmail.com>
+
+	PR modula2/121354
+	* gm2-compiler/M2GenGCC.mod (FoldHigh): Rewrite.
+	(IsUnboundedArray): New procedure function.
+
+2025-07-31  Gaius Mulley  <gaiusmod2@gmail.com>
+
+	PR modula2/121314
+	* mc-boot/GFormatStrings.cc (PerformFormatString): Rebuilt.
+	* mc-boot/GM2EXCEPTION.cc (M2EXCEPTION_M2Exception): Rebuilt.
+	* mc-boot/GSFIO.cc (SFIO_GetFileName): Rebuilt.
+	* mc-boot/GSFIO.h (SFIO_GetFileName): Rebuilt.
+	* mc-boot/Gdecl.cc: Rebuilt.
+	* mc-boot/GmcFileName.h: Rebuilt.
+	* mc/decl.mod (getStringChar): New procedure function.
+	(getStringContents): Call getStringChar.
+	(addQuotes): New procedure function.
+	(foldBinary): Call addQuotes to add delimiting quotes
+	to the new string.
+
+2025-07-29  Gaius Mulley  <gaiusmod2@gmail.com>
+
+	* gm2-compiler/M2GenGCC.mod (FoldBecomes): Remove all
+	local variables.
+	(CodeIndrX): Remove length.
+	Remove newstr.
+	* gm2-compiler/M2Range.mod (FoldTypeIndrX): Remove desType.
+
+2025-07-29  Gaius Mulley  <gaiusmod2@gmail.com>
+
+	PR modula2/121289
+	* gm2-compiler/M2Students.def (CheckVariableAgainstKeyword): New
+	parameter tok.
+	* gm2-compiler/M2Students.mod (CheckVariableAgainstKeyword): New
+	parameter tok.
+	Pass tok to PerformVariableKeywordCheck.
+	(PerformVariableKeywordCheck): New parameter tok.
+	Pass tok to MetaErrorStringT0.
+	* gm2-compiler/P2SymBuild.mod (BuildVariable): Pass tok to
+	CheckVariableAgainstKeyword.
+	* gm2-libs-iso/LowLong.mod (except): Replace with ...
+	(exceptSrc): ... this.
+	* gm2-libs-iso/LowReal.mod (except): Replace with ...
+	(exceptSrc): ... this.
+	* gm2-libs-iso/LowShort.mod (except): Replace with ...
+	(exceptSrc): ... this.
+	* gm2-libs-iso/Processes.mod (Wait): Replace from with fromCor.
+	* gm2-libs-iso/RndFile.mod (EndPos): Replace end with endP.
+	* gm2-libs/SCmdArgs.mod (GetArg): Replace start with startPos.
+	Replace end with endPos.
+	(NArg): Replace start with startPos.
+	Replace end with endPos.
+
 2025-07-25  David Malcolm  <dmalcolm@redhat.com>
 
 	* gm2-gcc/m2linemap.cc: Update usage of "diagnostic_info" to
diff --git a/gcc/m2/gm2-compiler/M2GenGCC.mod b/gcc/m2/gm2-compiler/M2GenGCC.mod
index 4a9ced3..2440b2a 100644
--- a/gcc/m2/gm2-compiler/M2GenGCC.mod
+++ b/gcc/m2/gm2-compiler/M2GenGCC.mod
@@ -2903,9 +2903,6 @@ END CheckStop ;
 *)
 
 PROCEDURE FoldBecomes (p: WalkAction; bb: BasicBlock; quad: CARDINAL) ;
-VAR
-   op            : QuadOperator ;
-   des, op2, expr: CARDINAL ;
 BEGIN
    IF DeclaredOperandsBecomes (p, quad)
    THEN
@@ -6442,37 +6439,52 @@ END ResolveHigh ;
 
 
 (*
+   IsUnboundedArray - return TRUE if symbol is an unbounded array.
+*)
+
+PROCEDURE IsUnboundedArray (sym: CARDINAL) : BOOLEAN ;
+BEGIN
+   IF IsParameter (sym) OR IsVar (sym)
+   THEN
+      RETURN IsUnbounded (GetType (sym))
+   END ;
+   RETURN FALSE
+END IsUnboundedArray ;
+
+
+(*
    FoldHigh - if the array is not dynamic then we should be able to
               remove the HighOp quadruple and assign op1 with
-              the known compile time HIGH(op3).
+              the known compile time HIGH(array).
 *)
 
 PROCEDURE FoldHigh (tokenno: CARDINAL; p: WalkAction;
-                    quad: CARDINAL; op1, dim, op3: CARDINAL) ;
+                    quad: CARDINAL; op1, dim, array: CARDINAL) ;
 VAR
    t       : tree ;
    location: location_t ;
 BEGIN
-   (* firstly ensure that any constant literal is declared *)
-   TryDeclareConstant(tokenno, op3) ;
-   location := TokenToLocation(tokenno) ;
-   IF GccKnowsAbout(op3) AND CompletelyResolved(op3)
+   (* Firstly ensure that any constant literal is declared.  *)
+   TryDeclareConstant (tokenno, array) ;
+   location := TokenToLocation (tokenno) ;
+   IF (NOT IsUnboundedArray (array)) AND
+      GccKnowsAbout (array) AND CompletelyResolved (array)
    THEN
-      t := ResolveHigh(tokenno, dim, op3) ;
-      (* fine, we can take advantage of this and fold constants *)
-      IF IsConst(op1) AND (t#tree(NIL))
+      t := ResolveHigh (tokenno, dim, array) ;
+      (* We can take advantage of this and fold constants.  *)
+      IF IsConst (op1) AND (t # tree (NIL))
       THEN
-         PutConst(op1, Cardinal) ;
-         AddModGcc(op1,
-                   DeclareKnownConstant(location, GetCardinalType(),
-                                        ToCardinal(location, t))) ;
-         p(op1) ;
+         PutConst (op1, Cardinal) ;
+         AddModGcc (op1,
+                    DeclareKnownConstant (location, GetCardinalType (),
+                                          ToCardinal (location, t))) ;
+         p (op1) ;
          NoChange := FALSE ;
-         SubQuad(quad)
+         SubQuad (quad)
       ELSE
-         (* we can still fold the expression, but not the assignment, however, we will
-            not do this here but in CodeHigh
-         *)
+         (* We can still fold the expression but not the assignment,
+            we will not do this here but in CodeHigh when the result
+            can be stored.  *)
       END
    END
 END FoldHigh ;
@@ -8154,8 +8166,6 @@ VAR
    rightpos,
    typepos,
    indrxpos        : CARDINAL ;
-   length,
-   newstr          : tree ;
    location        : location_t ;
 BEGIN
    GetQuadOtok (quad, indrxpos, op, left, type, right,
diff --git a/gcc/m2/gm2-compiler/M2Range.mod b/gcc/m2/gm2-compiler/M2Range.mod
index dcac2ba..f1516d3 100644
--- a/gcc/m2/gm2-compiler/M2Range.mod
+++ b/gcc/m2/gm2-compiler/M2Range.mod
@@ -1869,14 +1869,12 @@ END FoldTypeAssign ;
 
 PROCEDURE FoldTypeIndrX (q: CARDINAL; tokenNo: CARDINAL; des, expr: CARDINAL; r: CARDINAL) ;
 VAR
-   desType,
    exprType: CARDINAL ;
 BEGIN
    (* Need to skip over a variable or temporary in des and expr so
       long as expr is not a procedure.  In the case of des = *expr,
       both expr and des will be variables due to the property of
       indirection.  *)
-   desType := GetType (des) ;
    IF IsProcedure (expr)
    THEN
       (* Must not GetType for a procedure as it gives the return type.  *)
diff --git a/gcc/m2/gm2-compiler/M2Students.def b/gcc/m2/gm2-compiler/M2Students.def
index 7d67a0a..a3ecdcd 100644
--- a/gcc/m2/gm2-compiler/M2Students.def
+++ b/gcc/m2/gm2-compiler/M2Students.def
@@ -39,7 +39,7 @@ EXPORT QUALIFIED StudentVariableCheck, CheckVariableAgainstKeyword ;
                                  as a keyword except for its case.
 *)
 
-PROCEDURE CheckVariableAgainstKeyword (name: Name) ;
+PROCEDURE CheckVariableAgainstKeyword (tok: CARDINAL; name: Name) ;
 
 
 (*
diff --git a/gcc/m2/gm2-compiler/M2Students.mod b/gcc/m2/gm2-compiler/M2Students.mod
index e539eb0..3df160a 100644
--- a/gcc/m2/gm2-compiler/M2Students.mod
+++ b/gcc/m2/gm2-compiler/M2Students.mod
@@ -25,7 +25,7 @@ IMPLEMENTATION MODULE M2Students ;
 FROM SymbolTable IMPORT FinalSymbol, IsVar, IsProcedure, IsModule,
                         GetMainModule, IsType, NulSym, IsRecord, GetSymName, GetNth, GetNthProcedure, GetDeclaredMod, NoOfParam ;
 FROM NameKey IMPORT GetKey, WriteKey, MakeKey, IsSameExcludingCase, NulName, makekey, KeyToCharStar ;
-FROM M2MetaError IMPORT MetaErrorString0, MetaError2 ;
+FROM M2MetaError IMPORT MetaErrorStringT0, MetaError2 ;
 FROM Lists IMPORT List, InitList, IsItemInList, IncludeItemIntoList ;
 FROM M2Reserved IMPORT IsReserved, toktype ;
 FROM DynamicStrings IMPORT String, InitString, KillString, ToUpper, InitStringCharStar, string, Mark, ToUpper, Dup ;
@@ -78,11 +78,11 @@ END IsNotADuplicateName ;
                                  as a keyword except for its case.
 *)
 
-PROCEDURE CheckVariableAgainstKeyword (name: Name) ;
+PROCEDURE CheckVariableAgainstKeyword (tok: CARDINAL; name: Name) ;
 BEGIN
    IF StyleChecking
    THEN
-      PerformVariableKeywordCheck (name)
+      PerformVariableKeywordCheck (tok, name)
    END
 END CheckVariableAgainstKeyword ;
 
@@ -91,7 +91,7 @@ END CheckVariableAgainstKeyword ;
    PerformVariableKeywordCheck - performs the check and constructs the metaerror notes if appropriate.
 *)
 
-PROCEDURE PerformVariableKeywordCheck (name: Name) ;
+PROCEDURE PerformVariableKeywordCheck (tok: CARDINAL; name: Name) ;
 VAR
    upper : Name ;
    token : toktype ;
@@ -105,9 +105,11 @@ BEGIN
    THEN
       IF IsNotADuplicateName (name)
       THEN
-         MetaErrorString0 (Sprintf2 (Mark (InitString ('either the identifier has the same name as a keyword or alternatively a keyword has the wrong case ({%%K%s} and {!%%O:{%%K%s}})')),
-                                     upperS, orig)) ;
-         MetaErrorString0 (Sprintf1 (Mark (InitString ('the symbol name {!%%O:{%%K%s}} is legal as an identifier, however as such it might cause confusion and is considered bad programming practice')), orig))
+         MetaErrorStringT0 (tok,
+                            Sprintf2 (Mark (InitString ('either the identifier has the same name as a keyword or alternatively a keyword has the wrong case ({%%K%s} and {!%%O:{%%K%s}})')),
+                                      upperS, orig)) ;
+         MetaErrorStringT0 (tok,
+                            Sprintf1 (Mark (InitString ('the symbol name {!%%O:{%%K%s}} is legal as an identifier, however as such it might cause confusion and is considered bad programming practice')), orig))
       END
    END ;
    upperS := KillString (upperS) ;
diff --git a/gcc/m2/gm2-compiler/P2SymBuild.mod b/gcc/m2/gm2-compiler/P2SymBuild.mod
index 3bb3e47..54e624f 100644
--- a/gcc/m2/gm2-compiler/P2SymBuild.mod
+++ b/gcc/m2/gm2-compiler/P2SymBuild.mod
@@ -1179,8 +1179,8 @@ BEGIN
    PopT (n) ;
    i := 1 ;
    WHILE i <= n DO
-      CheckVariableAgainstKeyword (OperandT (n+1-i)) ;
       tok := OperandTok (n+1-i) ;
+      CheckVariableAgainstKeyword (tok, OperandT (n+1-i)) ;
       Var := MakeVar (tok, OperandT (n+1-i)) ;
       AtAddress := OperandA (n+1-i) ;
       IF AtAddress # NulSym
diff --git a/gcc/m2/gm2-compiler/PathName.mod b/gcc/m2/gm2-compiler/PathName.mod
index 6fc7612..0ba9024 100644
--- a/gcc/m2/gm2-compiler/PathName.mod
+++ b/gcc/m2/gm2-compiler/PathName.mod
@@ -1,3 +1,24 @@
+(* M2PathName.mod maintain a dictionary of named paths.
+
+Copyright (C) 2023-2025 Free Software Foundation, Inc.
+Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.
+
+This file is part of GNU Modula-2.
+
+GNU Modula-2 is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GNU Modula-2 is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Modula-2; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  *)
+
 IMPLEMENTATION MODULE PathName ;
 
 FROM Storage IMPORT ALLOCATE, DEALLOCATE ;
diff --git a/gcc/m2/gm2-lang.cc b/gcc/m2/gm2-lang.cc
index 31a2e46..cc074d5 100644
--- a/gcc/m2/gm2-lang.cc
+++ b/gcc/m2/gm2-lang.cc
@@ -40,6 +40,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "m2-tree.h"
 #include "convert.h"
 #include "rtegraph.h"
+#include "cppdefault.h"
 
 static void write_globals (void);
 
@@ -51,6 +52,7 @@ static bool iso = false;
 typedef struct named_path_s {
   std::vector<const char*>path;
   const char *name;
+  bool lib_root;
 } named_path;
 
 
@@ -59,6 +61,7 @@ static bool allow_libraries = true;
 static const char *flibs = nullptr;
 static const char *iprefix = nullptr;
 static const char *imultilib = nullptr;
+static const char *target_system_root = nullptr;
 static std::vector<named_path>Ipaths;
 static std::vector<const char*>isystem;
 static std::vector<const char*>iquote;
@@ -372,6 +375,7 @@ push_back_Ipath (const char *arg)
       named_path np;
       np.path.push_back (arg);
       np.name = xstrdup (M2Options_GetM2PathName ());
+      np.lib_root = false;
       Ipaths.push_back (np);
     }
   else
@@ -384,11 +388,254 @@ push_back_Ipath (const char *arg)
 	  named_path np;
 	  np.path.push_back (arg);
 	  np.name = xstrdup (M2Options_GetM2PathName ());
+	  np.lib_root = false;
 	  Ipaths.push_back (np);
 	}
     }
 }
 
+/* push_back_lib_root pushes a lib_root onto the Ipaths vector.
+   The ordering of the -fm2_add_lib_root=, -I and named paths
+   must be preserved.  */
+
+static void
+push_back_lib_root (const char *arg)
+{
+  named_path np;
+  np.name = arg;
+  np.lib_root = true;
+  Ipaths.push_back (np);
+}
+
+/* get_dir_sep_size return the length of the DIR_SEPARATOR string.  */
+
+static size_t
+get_dir_sep_size (void)
+{
+  const char dir_sep[] = {DIR_SEPARATOR, (char)0};
+  size_t dir_sep_size = strlen (dir_sep);
+  return dir_sep_size;
+}
+
+/* add_path_component strcats src into dest and adds a directory seperator
+   if necessary.  */
+
+static void
+add_path_component (char *dest, const char *src)
+{
+  size_t len = strlen (dest);
+  const char dir_sep[] = {DIR_SEPARATOR, (char)0};
+  size_t dir_sep_size = strlen (dir_sep);
+
+  if (len > 0)
+    {
+      /* Only add a seperator if dest is not empty and does not end
+	 with a seperator.  */
+      if (len >= dir_sep_size
+	  && (strcmp (&dest[len-dir_sep_size], dir_sep) != 0))
+	strcat (dest, dir_sep);
+    }
+  strcat (dest, src);
+}
+
+/* This prefixes LIBNAME with the current compiler prefix (if it has been
+   relocated) or the LIBSUBDIR, if not.  */
+
+static void
+add_one_import_path (const char *libpath, const char *libname)
+{
+  size_t dir_sep_size = get_dir_sep_size ();
+  size_t mlib_len = 0;
+
+  if (imultilib)
+    {
+      mlib_len = strlen (imultilib);
+      mlib_len += dir_sep_size;
+    }
+
+  char *lib = (char *)alloca (strlen (libpath) + dir_sep_size
+			      + strlen ("m2") + dir_sep_size
+			      + strlen (libname) + 1
+			      + mlib_len + 1);
+  strcpy (lib, libpath);
+  if (imultilib)
+    add_path_component (lib, imultilib);
+  add_path_component (lib, "m2");
+  add_path_component (lib, libname);
+  M2Options_SetM2PathName (libname);
+  M2Options_SetSearchPath (lib);
+}
+
+/* add_non_dialect_specific_path add non dialect specific includes
+   given a base libpath.  */
+
+static void
+add_non_dialect_specific_path (const char *libpath)
+{
+  char *incpath = (char *)alloca (strlen (libpath)
+				  + strlen ("m2")
+				  + get_dir_sep_size ()
+				  + 1);
+  strcpy (incpath, libpath);
+  add_path_component (incpath, "m2");
+  M2Options_SetM2PathName ("");   /* No pathname for non dialect specific libs.  */
+  M2Options_SetSearchPath (incpath);
+}
+
+/* For each comma-separated standard library name in LIBLIST, add the
+   corresponding include path.  */
+
+static void
+foreach_lib_gen_import_path (const char *liblist, const char *libpath)
+{
+  while (*liblist != 0 && *liblist != '-')
+    {
+      const char *comma = strstr (liblist, ",");
+      size_t len;
+      if (comma)
+	len = comma - liblist;
+      else
+	len = strlen (liblist);
+      char *libname = (char *) alloca (len+1);
+      strncpy (libname, liblist, len);
+      libname[len] = 0;
+      add_one_import_path (libpath, libname);
+      liblist += len;
+      if (*liblist == ',')
+	liblist++;
+    }
+  add_non_dialect_specific_path (libpath);
+}
+
+/* get_module_source_dir return the libpath/{multilib/} as a malloc'd
+   string.  */
+
+static const char *
+get_module_source_dir (void)
+{
+  const char *libpath = iprefix ? iprefix : LIBSUBDIR;
+  const char dir_sep[] = {DIR_SEPARATOR, (char)0};
+  size_t dir_sep_size = strlen (dir_sep);
+  unsigned int mlib_len = 0;
+
+  if (imultilib)
+    {
+      mlib_len = strlen (imultilib);
+      mlib_len += strlen (dir_sep);
+    }
+  char *lib = (char *) xmalloc (strlen (libpath)
+				+ dir_sep_size
+				+ mlib_len + 1);
+  strcpy (lib, libpath);
+  /* iprefix has a trailing dir separator, LIBSUBDIR does not.  */
+  if (!iprefix)
+    strcat (lib, dir_sep);
+
+  if (imultilib)
+    {
+      strcat (lib, imultilib);
+      strcat (lib, dir_sep);
+    }
+  return lib;
+}
+
+/* concat_component returns a string containing the path left/right.
+   Pre-requisite, left and right are null terminated strings.  The contents of
+   left and right are held on the heap.  Post-requisite, left and right are
+   freed and a new combined string is malloced.  */
+
+static char *
+concat_component (char *left, char *right)
+{
+  size_t len = strlen (left)
+    + strlen (right)
+    + get_dir_sep_size ()
+    + 1;
+  char *new_str = (char *) xmalloc (len);
+  strcpy (new_str, left);
+  add_path_component (new_str, right);
+  free (left);
+  free (right);
+  return new_str;
+}
+
+/* find_cpp_entry return the element of the cpp_include_defaults array
+   whose fname matches name.  */
+
+static const struct default_include *
+find_cpp_entry (const char *name)
+{
+  const struct default_include *p;
+
+  for (p = cpp_include_defaults; p->fname; p++)
+    if (strcmp (p->fname, name) == 0)
+      return p;
+  return NULL;
+}
+
+/* lookup_cpp_default lookup the entry in cppdefault then add the directory to
+   the m2 search path.  It also honours sysroot, imultilib and imultiarch.  */
+
+static void
+lookup_cpp_default (const char *sysroot, const char *flibs, const char *name)
+{
+  const struct default_include *p = find_cpp_entry (name);
+
+  if (p != NULL)
+    {
+      char *full_str = xstrdup (p->fname);
+
+      /* Should this directory start with the sysroot?  */
+      if (sysroot && p->add_sysroot)
+	full_str = concat_component (xstrdup (sysroot), full_str);
+      /* Should we append the imultilib component?  */
+      if (p->multilib == 1 && imultilib)
+	full_str = concat_component (full_str, xstrdup (imultilib));
+      /* Or append the imultiarch component?  */
+      else if (p->multilib == 2 && imultiarch)
+	full_str = concat_component (full_str, xstrdup (imultiarch));
+      else
+	full_str = xstrdup (p->fname);
+      foreach_lib_gen_import_path (flibs, full_str);
+      free (full_str);
+    }
+}
+
+/* add_default_include_paths add include paths for site wide definition modules
+   and also gcc version specific definition modules.  */
+
+static void
+add_default_include_paths (const char *flibs)
+{
+  /* Follow the order found in cppdefaults.cc.  */
+#ifdef LOCAL_INCLUDE_DIR
+  lookup_cpp_default (target_system_root, flibs, LOCAL_INCLUDE_DIR);
+#endif
+#ifdef PREFIX_INCLUDE_DIR
+  lookup_cpp_default (target_system_root, flibs, PREFIX_INCLUDE_DIR);
+#endif
+  /* Add the gcc version specific include path.  */
+  foreach_lib_gen_import_path (flibs, get_module_source_dir ());
+#ifdef NATIVE_SYSTEM_HEADER_DIR
+  lookup_cpp_default (target_system_root, flibs, NATIVE_SYSTEM_HEADER_DIR);
+#endif
+}
+
+/* assign_flibs assign flibs to a default providing that allow_libraries
+   is true and flibs has not been set.  */
+
+static void
+assign_flibs (void)
+{
+  if (allow_libraries && (flibs == NULL))
+    {
+      if (iso)
+	flibs = "m2iso,m2cor,m2pim,m2log";
+      else
+	flibs = "m2pim,m2iso,m2cor,m2log";
+    }
+}
+
 /* Handle gm2 specific options.  Return 0 if we didn't do anything.  */
 
 bool
@@ -435,6 +682,9 @@ gm2_langhook_handle_option (
     case OPT_fpositive_mod_floor_div:
       M2Options_SetPositiveModFloor (value);
       return 1;
+    case OPT_fm2_pathname_rootI_:
+      push_back_lib_root (arg);
+      return 1;
     case OPT_flibs_:
       allow_libraries = value;
       flibs = arg;
@@ -659,7 +909,7 @@ gm2_langhook_handle_option (
       return 1;
       break;
     case OPT_isysroot:
-      /* Otherwise, ignored, at least for now. */
+      target_system_root = arg;
       return 1;
       break;
     case OPT_fm2_whole_program:
@@ -710,66 +960,6 @@ gm2_langhook_handle_option (
   return 0;
 }
 
-/* This prefixes LIBNAME with the current compiler prefix (if it has been
-   relocated) or the LIBSUBDIR, if not.  */
-static void
-add_one_import_path (const char *libname)
-{
-  const char *libpath = iprefix ? iprefix : LIBSUBDIR;
-  const char dir_sep[] = {DIR_SEPARATOR, (char)0};
-  size_t dir_sep_size = strlen (dir_sep);
-  unsigned int mlib_len = 0;
-
-  if (imultilib)
-    {
-      mlib_len = strlen (imultilib);
-      mlib_len += strlen (dir_sep);
-    }
-
-  char *lib = (char *)alloca (strlen (libpath) + dir_sep_size
-			      + strlen ("m2") + dir_sep_size
-			      + strlen (libname) + 1
-			      + mlib_len + 1);
-  strcpy (lib, libpath);
-  /* iprefix has a trailing dir separator, LIBSUBDIR does not.  */
-  if (!iprefix)
-    strcat (lib, dir_sep);
-
-  if (imultilib)
-    {
-      strcat (lib, imultilib);
-      strcat (lib, dir_sep);
-    }
-  strcat (lib, "m2");
-  strcat (lib, dir_sep);
-  strcat (lib, libname);
-  M2Options_SetM2PathName (libname);
-  M2Options_SetSearchPath (lib);
-}
-
-/* For each comma-separated standard library name in LIBLIST, add the
-   corresponding include path.  */
-static void
-add_m2_import_paths (const char *liblist)
-{
-  while (*liblist != 0 && *liblist != '-')
-    {
-      const char *comma = strstr (liblist, ",");
-      size_t len;
-      if (comma)
-	len = comma - liblist;
-      else
-	len = strlen (liblist);
-      char *libname = (char *) alloca (len+1);
-      strncpy (libname, liblist, len);
-      libname[len] = 0;
-      add_one_import_path (libname);
-      liblist += len;
-      if (*liblist == ',')
-	liblist++;
-    }
-}
-
 /* Run after parsing options.  */
 
 static bool
@@ -784,16 +974,7 @@ gm2_langhook_post_options (const char **pfilename)
   /* Add the include paths as per the libraries specified.
      NOTE: This assumes that the driver has validated the input and makes
      no attempt to be defensive of nonsense input in flibs=.  */
-  if (allow_libraries)
-    {
-      if (!flibs)
-	{
-	  if (iso)
-	    flibs = "m2iso,m2cor,m2pim,m2log";
-	  else
-	    flibs = "m2pim,m2iso,m2cor,m2log";
-	}
-    }
+  assign_flibs ();
 
   /* Add search paths.
      We are not handling all of the cases yet (e.g idirafter).
@@ -807,9 +988,14 @@ gm2_langhook_post_options (const char **pfilename)
   iquote.clear();
   for (auto np : Ipaths)
     {
-      M2Options_SetM2PathName (np.name);
-      for (auto *s : np.path)
-	M2Options_SetSearchPath (s);
+      if (np.lib_root)
+	foreach_lib_gen_import_path (flibs, np.name);
+      else
+	{
+	  M2Options_SetM2PathName (np.name);
+	  for (auto *s : np.path)
+	    M2Options_SetSearchPath (s);
+	}
     }
   Ipaths.clear();
   for (auto *s : isystem)
@@ -818,7 +1004,7 @@ gm2_langhook_post_options (const char **pfilename)
   /* FIXME: this is not a good way to suppress the addition of the import
      paths.  */
   if (allow_libraries)
-    add_m2_import_paths (flibs);
+    add_default_include_paths (flibs);
 
   /* Returning false means that the backend should be used.  */
   return M2Options_GetPPOnly ();
diff --git a/gcc/m2/gm2-libs-iso/LowLong.mod b/gcc/m2/gm2-libs-iso/LowLong.mod
index 92c7d91..f611923 100644
--- a/gcc/m2/gm2-libs-iso/LowLong.mod
+++ b/gcc/m2/gm2-libs-iso/LowLong.mod
@@ -182,7 +182,7 @@ BEGIN
    IF n<0
    THEN
       (* exception raised *)
-      RAISE(except, ORD(badparam),
+      RAISE(exceptSrc, ORD(badparam),
             'LowLong.trunc: cannot truncate to a negative number of digits') ;
       RETURN x
    ELSE
@@ -230,7 +230,7 @@ BEGIN
    IF n<0
    THEN
       (* exception raised *)
-      RAISE(except, ORD(badparam),
+      RAISE(exceptSrc, ORD(badparam),
             'LowLong.round: cannot round to a negative number of digits') ;
       RETURN x
    ELSE
@@ -287,12 +287,12 @@ END currentMode ;
 
 PROCEDURE IsLowException () : BOOLEAN ;
 BEGIN
-   RETURN( IsExceptionalExecution() AND IsCurrentSource(except) )
+   RETURN( IsExceptionalExecution () AND IsCurrentSource (exceptSrc) )
 END IsLowException ;
 
 
 VAR
-   except: ExceptionSource ;
+   exceptSrc: ExceptionSource ;
 BEGIN
-   AllocateSource(except)
+   AllocateSource (exceptSrc)
 END LowLong.
diff --git a/gcc/m2/gm2-libs-iso/LowReal.mod b/gcc/m2/gm2-libs-iso/LowReal.mod
index 580f36b..6d9ea00 100644
--- a/gcc/m2/gm2-libs-iso/LowReal.mod
+++ b/gcc/m2/gm2-libs-iso/LowReal.mod
@@ -183,8 +183,8 @@ BEGIN
    IF n<0
    THEN
       (* exception raised *)
-      RAISE(except, ORD(badparam),
-            'LowReal.trunc: cannot truncate to a negative number of digits') ;
+      RAISE (exceptSrc, ORD(badparam),
+             'LowReal.trunc: cannot truncate to a negative number of digits') ;
       RETURN x
    ELSE
       r := dtoa(x, maxsignificant, 100, point, sign) ;
@@ -231,8 +231,8 @@ BEGIN
    IF n<0
    THEN
       (* exception raised *)
-      RAISE(except, ORD(badparam),
-            'LowReal.round: cannot round to a negative number of digits') ;
+      RAISE (exceptSrc, ORD(badparam),
+             'LowReal.round: cannot round to a negative number of digits') ;
       RETURN x
    ELSE
       s := RealToFloatString(x, n) ;
@@ -288,12 +288,12 @@ END currentMode ;
 
 PROCEDURE IsLowException () : BOOLEAN ;
 BEGIN
-   RETURN( IsExceptionalExecution() AND IsCurrentSource(except) )
+   RETURN( IsExceptionalExecution () AND IsCurrentSource (exceptSrc) )
 END IsLowException ;
 
 
 VAR
-   except: ExceptionSource ;
+   exceptSrc: ExceptionSource ;
 BEGIN
-   AllocateSource(except)
+   AllocateSource (exceptSrc)
 END LowReal.
diff --git a/gcc/m2/gm2-libs-iso/LowShort.mod b/gcc/m2/gm2-libs-iso/LowShort.mod
index 8531a88..62e4887 100644
--- a/gcc/m2/gm2-libs-iso/LowShort.mod
+++ b/gcc/m2/gm2-libs-iso/LowShort.mod
@@ -183,8 +183,8 @@ BEGIN
    IF n<0
    THEN
       (* exception raised *)
-      RAISE(except, ORD(badparam),
-            'LowLong.trunc: cannot truncate to a negative number of digits') ;
+      RAISE (exceptSrc, ORD(badparam),
+             'LowLong.trunc: cannot truncate to a negative number of digits') ;
       RETURN x
    ELSE
       r := dtoa(x, maxsignificant, 100, point, sign) ;
@@ -231,8 +231,8 @@ BEGIN
    IF n<0
    THEN
       (* exception raised *)
-      RAISE(except, ORD(badparam),
-            'LowLong.round: cannot round to a negative number of digits') ;
+      RAISE (exceptSrc, ORD(badparam),
+             'LowLong.round: cannot round to a negative number of digits') ;
       RETURN x
    ELSE
       s := RealToFloatString(x, n) ;
@@ -288,12 +288,12 @@ END currentMode ;
 
 PROCEDURE IsLowException () : BOOLEAN ;
 BEGIN
-   RETURN( IsExceptionalExecution() AND IsCurrentSource(except) )
+   RETURN( IsExceptionalExecution () AND IsCurrentSource (exceptSrc) )
 END IsLowException ;
 
 
 VAR
-   except: ExceptionSource ;
+   exceptSrc: ExceptionSource ;
 BEGIN
-   AllocateSource(except)
+   AllocateSource (exceptSrc)
 END LowShort.
diff --git a/gcc/m2/gm2-libs-iso/Processes.mod b/gcc/m2/gm2-libs-iso/Processes.mod
index 8ef22c0..b0c1b69 100644
--- a/gcc/m2/gm2-libs-iso/Processes.mod
+++ b/gcc/m2/gm2-libs-iso/Processes.mod
@@ -441,7 +441,7 @@ PROCEDURE Wait ;
 VAR
    calling,
    best   : ProcessId ;
-   from   : COROUTINE ;
+   fromCor: COROUTINE ;
 BEGIN
    IF debugging
    THEN
@@ -451,17 +451,17 @@ BEGIN
    OnWaitingQueue (calling) ;
    best := chooseProcess () ;
    currentId := best ;
-   from := calling^.context ;
+   fromCor := calling^.context ;
    IF debugging
    THEN
       displayProcesses ("Wait about to perform IOTRANSFER")
    END ;
-   IOTRANSFER (from, currentId^.context) ;
+   IOTRANSFER (fromCor, currentId^.context) ;
    IF debugging
    THEN
       displayProcesses ("Wait after IOTRANSFER")
    END ;
-   currentId^.context := from ;
+   currentId^.context := fromCor ;
    currentId := calling ;
    OnReadyQueue (calling) ;
    IF debugging
diff --git a/gcc/m2/gm2-libs-iso/RndFile.mod b/gcc/m2/gm2-libs-iso/RndFile.mod
index e04cd8f..0a2264a 100644
--- a/gcc/m2/gm2-libs-iso/RndFile.mod
+++ b/gcc/m2/gm2-libs-iso/RndFile.mod
@@ -398,9 +398,9 @@ PROCEDURE EndPos (cid: ChanId): FilePos;
      position after which there have been no writes.
   *)
 VAR
-   d  : DeviceTablePtr ;
-   end,
-   old: FilePos ;
+   d   : DeviceTablePtr ;
+   endP,
+   old : FilePos ;
 BEGIN
    IF IsRndFile(cid)
    THEN
@@ -410,9 +410,9 @@ BEGIN
          old := CurrentPos(cid) ;
          FIO.SetPositionFromEnd(RTio.GetFile(cid), 0) ;
          checkErrno(dev, d) ;
-         end := CurrentPos(cid) ;
+         endP := CurrentPos(cid) ;
          FIO.SetPositionFromBeginning(RTio.GetFile(cid), old) ;
-         RETURN( end )
+         RETURN( endP )
       END
    ELSE
       RAISEdevException(cid, did, IOChan.wrongDevice,
diff --git a/gcc/m2/gm2-libs/SCmdArgs.mod b/gcc/m2/gm2-libs/SCmdArgs.mod
index ed76fc4..8443d5f 100644
--- a/gcc/m2/gm2-libs/SCmdArgs.mod
+++ b/gcc/m2/gm2-libs/SCmdArgs.mod
@@ -132,26 +132,27 @@ PROCEDURE GetArg (CmdLine: String;
 VAR
    i         : CARDINAL ;
    sn,
-   start, end: INTEGER ;
+   startPos,
+   endPos    : INTEGER ;
    ch        : CHAR ;
 BEGIN
    i := 0 ;
-   start := 0 ;
-   end := Length(CmdLine) ;
+   startPos := 0 ;
+   endPos := Length(CmdLine) ;
    WHILE i<n DO
-      start := skipWhite(CmdLine, start, end) ;
-      sn := skipNextArg(CmdLine, start, end) ;
-      IF sn<end
+      startPos := skipWhite(CmdLine, startPos, endPos) ;
+      sn := skipNextArg(CmdLine, startPos, endPos) ;
+      IF sn<endPos
       THEN
-         start := sn ;
+         startPos := sn ;
          INC(i)
       ELSE
          RETURN( FALSE )
       END
    END ;
-   start := skipWhite(CmdLine, start, end) ;
-   sn := skipNextArg(CmdLine, start, end) ;
-   Argi := Slice(CmdLine, start, sn) ;
+   startPos := skipWhite(CmdLine, startPos, endPos) ;
+   sn := skipNextArg(CmdLine, startPos, endPos) ;
+   Argi := Slice(CmdLine, startPos, sn) ;
    RETURN( TRUE )
 END GetArg ;
 
@@ -165,17 +166,18 @@ PROCEDURE Narg (CmdLine: String) : CARDINAL ;
 VAR
    n         : CARDINAL ;
    s,
-   start, end: INTEGER ;
+   startPos,
+   endPos    : INTEGER ;
 BEGIN
    n := 0 ;
-   start := 0 ;
-   end := Length(CmdLine) ;
+   startPos := 0 ;
+   endPos := Length(CmdLine) ;
    LOOP
-      start := skipWhite(CmdLine, start, end) ;
-      s := skipNextArg(CmdLine, start, end) ;
-      IF s<end
+      startPos := skipWhite(CmdLine, startPos, endPos) ;
+      s := skipNextArg(CmdLine, startPos, endPos) ;
+      IF s<endPos
       THEN
-         start := s ;
+         startPos := s ;
          INC(n)
       ELSE
          RETURN( n )
diff --git a/gcc/m2/gm2spec.cc b/gcc/m2/gm2spec.cc
index 868e5c5..18d9ce7 100644
--- a/gcc/m2/gm2spec.cc
+++ b/gcc/m2/gm2spec.cc
@@ -158,10 +158,12 @@ static const char *m2_path_name = "";
 typedef struct named_path_s {
   std::vector<const char*>path;
   const char *name;
+  bool lib_root;
 } named_path;
 
 static std::vector<named_path>Ipaths;
 
+/* push_back_Ipath pushes a named path to the Ipaths global variable.  */
 
 static void
 push_back_Ipath (const char *arg)
@@ -171,6 +173,7 @@ push_back_Ipath (const char *arg)
       named_path np;
       np.path.push_back (arg);
       np.name = m2_path_name;
+      np.lib_root = false;
       Ipaths.push_back (np);
     }
   else
@@ -183,11 +186,25 @@ push_back_Ipath (const char *arg)
 	  named_path np;
 	  np.path.push_back (arg);
 	  np.name = m2_path_name;
+	  np.lib_root = false;
 	  Ipaths.push_back (np);
 	}
     }
 }
 
+/* push_back_lib_root pushes a lib_root onto the Ipaths vector.
+   The ordering of the -fm2_add_lib_root=, -I and named paths
+   must be preserved.  */
+
+static void
+push_back_lib_root (const char *arg)
+{
+  named_path np;
+  np.name = arg;
+  np.lib_root = true;
+  Ipaths.push_back (np);
+}
+
 /* Return whether strings S1 and S2 are both NULL or both the same
    string.  */
 
@@ -379,15 +396,18 @@ convert_abbreviations (const char *libraries)
   return full_libraries;
 }
 
-/* add_m2_I_path appends -fm2-pathname and -fm2-pathnameI options to
-   the command line which are contructed in the saved Ipaths.  */
+/* add_m2_I_path appends -fm2-pathname, -fm2-pathnameI and -fm2-add-lib-root
+   options to the command line which are contructed in the saved Ipaths.
+   The order of these options must be maintained.  */
 
 static void
 add_m2_I_path (void)
 {
   for (auto np : Ipaths)
     {
-      if (strcmp (np.name, "") == 0)
+      if (np.lib_root)
+	append_option (OPT_fm2_pathname_rootI_, safe_strdup (np.name), 1);
+      else if (strcmp (np.name, "") == 0)
 	append_option (OPT_fm2_pathname_, safe_strdup ("-"), 1);
       else
 	append_option (OPT_fm2_pathname_, safe_strdup (np.name), 1);
@@ -576,6 +596,10 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
 	  args[i] |= SKIPOPT; /* We will add the option if it is needed.  */
 	  m2_path_name = decoded_options[i].arg;
 	  break;
+	case OPT_fm2_pathname_root_:
+	  args[i] |= SKIPOPT; /* We will add the option if it is needed.  */
+	  push_back_lib_root (decoded_options[i].arg);
+	  break;
 	case OPT__help:
 	case OPT__help_:
 	  /* Let gcc.cc handle this, as it has a really
@@ -739,7 +763,6 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
 	       "-fgen-module-list=", "-fuse-list=");
     }
 
-
   /* There's no point adding -shared-libgcc if we don't have a shared
      libgcc.  */
 #ifndef ENABLE_SHARED_LIBGCC
diff --git a/gcc/m2/lang.opt b/gcc/m2/lang.opt
index 48c2380..2aea4cc 100644
--- a/gcc/m2/lang.opt
+++ b/gcc/m2/lang.opt
@@ -172,7 +172,15 @@ specify the module mangled prefix name for all modules in the following include
 
 fm2-pathnameI
 Modula-2 Joined
-; For internal use only: used by the driver to copy the user facing -I option
+; For internal use only: used by the driver to copy the user facing -I option in order
+
+fm2-pathname-root=
+Modula-2 Joined
+add include paths for all the library names in -flibs= to this directory root
+
+fm2-pathname-rootI=
+Modula-2 Joined
+; For internal use only: used by the driver to copy the user facing -I option in order
 
 fm2-plugin
 Modula-2
diff --git a/gcc/m2/mc-boot/GFormatStrings.cc b/gcc/m2/mc-boot/GFormatStrings.cc
index f4c4fd6..ad7e7d8 100644
--- a/gcc/m2/mc-boot/GFormatStrings.cc
+++ b/gcc/m2/mc-boot/GFormatStrings.cc
@@ -464,7 +464,7 @@ static DynamicStrings_String PerformFormatString (DynamicStrings_String fmt, int
               /* avoid dangling else.  */
               afterperc += 1;
               Cast ((unsigned char *) &u, (sizeof (u)-1), (const unsigned char *) w, _w_high);
-              in = DynamicStrings_ConCat (in, DynamicStrings_Slice (fmt, (*startpos), nextperc));
+              in = Copy (fmt, in, (*startpos), nextperc);
               in = DynamicStrings_ConCat (in, StringConvert_CardinalToString (u, static_cast<unsigned int> (width), leader, 16, true));
               (*startpos) = afterperc;
               DSdbExit (static_cast<DynamicStrings_String> (NULL));
@@ -475,7 +475,7 @@ static DynamicStrings_String PerformFormatString (DynamicStrings_String fmt, int
               /* avoid dangling else.  */
               afterperc += 1;
               Cast ((unsigned char *) &u, (sizeof (u)-1), (const unsigned char *) w, _w_high);
-              in = DynamicStrings_ConCat (in, DynamicStrings_Slice (fmt, (*startpos), nextperc));
+              in = Copy (fmt, in, (*startpos), nextperc);
               in = DynamicStrings_ConCat (in, StringConvert_CardinalToString (u, static_cast<unsigned int> (width), leader, 10, false));
               (*startpos) = afterperc;
               DSdbExit (static_cast<DynamicStrings_String> (NULL));
diff --git a/gcc/m2/mc-boot/GM2EXCEPTION.cc b/gcc/m2/mc-boot/GM2EXCEPTION.cc
index 62d47f0..6baff3c 100644
--- a/gcc/m2/mc-boot/GM2EXCEPTION.cc
+++ b/gcc/m2/mc-boot/GM2EXCEPTION.cc
@@ -34,7 +34,6 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
        typedef struct { PROC_t proc; } PROC;
 #   endif
 
-#   include "Gmcrts.h"
 #define _M2EXCEPTION_C
 
 #include "GM2EXCEPTION.h"
@@ -51,18 +50,19 @@ extern "C" M2EXCEPTION_M2Exceptions M2EXCEPTION_M2Exception (void)
 
   /* If the program or coroutine is in the exception state then return the enumeration
    value representing the exception cause.  If it is not in the exception state then
-   raises and exception (exException).  */
+   raises an exException exception.  */
   e = RTExceptions_GetExceptionBlock ();
   n = RTExceptions_GetNumber (e);
   if (n == (UINT_MAX))
     {
       RTExceptions_Raise ( ((unsigned int) (M2EXCEPTION_exException)), const_cast<void*> (static_cast<const void*>("../../gcc/m2/gm2-libs/M2EXCEPTION.mod")), 47, 6, const_cast<void*> (static_cast<const void*>("M2Exception")), const_cast<void*> (static_cast<const void*>("current coroutine is not in the exceptional execution state")));
+      return M2EXCEPTION_exException;
     }
   else
     {
       return (M2EXCEPTION_M2Exceptions) (n);
     }
-  ReturnException ("../../gcc/m2/gm2-libs/M2EXCEPTION.def", 25, 1);
+  /* static analysis guarentees a RETURN statement will be used before here.  */
   __builtin_unreachable ();
 }
 
diff --git a/gcc/m2/mc-boot/GSFIO.cc b/gcc/m2/mc-boot/GSFIO.cc
index 6ae0d5e..f8c13d3 100644
--- a/gcc/m2/mc-boot/GSFIO.cc
+++ b/gcc/m2/mc-boot/GSFIO.cc
@@ -99,6 +99,13 @@ extern "C" DynamicStrings_String SFIO_WriteS (FIO_File file, DynamicStrings_Stri
 
 extern "C" DynamicStrings_String SFIO_ReadS (FIO_File file);
 
+/*
+   GetFileName - return a new string containing the name of the file.
+                 The string should be killed by the caller.
+*/
+
+extern "C" DynamicStrings_String SFIO_GetFileName (FIO_File file);
+
 
 /*
    Exists - returns TRUE if a file named, fname exists for reading.
@@ -207,6 +214,19 @@ extern "C" DynamicStrings_String SFIO_ReadS (FIO_File file)
   __builtin_unreachable ();
 }
 
+
+/*
+   GetFileName - return a new string containing the name of the file.
+                 The string should be killed by the caller.
+*/
+
+extern "C" DynamicStrings_String SFIO_GetFileName (FIO_File file)
+{
+  return DynamicStrings_InitStringCharStar (FIO_getFileName (file));
+  /* static analysis guarentees a RETURN statement will be used before here.  */
+  __builtin_unreachable ();
+}
+
 extern "C" void _M2_SFIO_init (__attribute__((unused)) int argc, __attribute__((unused)) char *argv[], __attribute__((unused)) char *envp[])
 {
 }
diff --git a/gcc/m2/mc-boot/GSFIO.h b/gcc/m2/mc-boot/GSFIO.h
index 42ffc48..93c8099 100644
--- a/gcc/m2/mc-boot/GSFIO.h
+++ b/gcc/m2/mc-boot/GSFIO.h
@@ -103,6 +103,13 @@ EXTERN DynamicStrings_String SFIO_WriteS (FIO_File file, DynamicStrings_String s
 */
 
 EXTERN DynamicStrings_String SFIO_ReadS (FIO_File file);
+
+/*
+   GetFileName - return a new string containing the name of the file.
+                 The string should be killed by the caller.
+*/
+
+EXTERN DynamicStrings_String SFIO_GetFileName (FIO_File file);
 #   ifdef __cplusplus
 }
 #   endif
diff --git a/gcc/m2/mc-boot/Gdecl.cc b/gcc/m2/mc-boot/Gdecl.cc
index ae03483..94ea098 100644
--- a/gcc/m2/mc-boot/Gdecl.cc
+++ b/gcc/m2/mc-boot/Gdecl.cc
@@ -2550,6 +2550,14 @@ static bool isLeafString (decl_node__opaque n);
 static DynamicStrings_String getLiteralStringContents (decl_node__opaque n);
 
 /*
+   getStringChar - if the string is delimited by single
+                   or double quotes then strip both
+                   quotes from the string.
+*/
+
+static DynamicStrings_String getStringChar (decl_node__opaque n);
+
+/*
    getStringContents - return the string contents of a constant, literal,
                        string or a constexp node.
 */
@@ -2569,7 +2577,13 @@ static nameKey_Name addNames (decl_node__opaque a, decl_node__opaque b);
 static decl_node__opaque resolveString (decl_node__opaque n);
 
 /*
-   foldBinary -
+   addQuotes - adds delimiter quote char to string.
+*/
+
+static DynamicStrings_String addQuotes (DynamicStrings_String s, char quote);
+
+/*
+   foldBinary - attempt to fold binary + for string constants.
 */
 
 static decl_node__opaque foldBinary (decl_nodeT k, decl_node__opaque l, decl_node__opaque r, decl_node__opaque res);
@@ -7590,6 +7604,32 @@ static DynamicStrings_String getLiteralStringContents (decl_node__opaque n)
 
 
 /*
+   getStringChar - if the string is delimited by single
+                   or double quotes then strip both
+                   quotes from the string.
+*/
+
+static DynamicStrings_String getStringChar (decl_node__opaque n)
+{
+  DynamicStrings_String s;
+
+  s = getString (n);
+  if (((DynamicStrings_char (s, 0)) == '\'') && ((DynamicStrings_char (s, -1)) == '\''))
+    {
+      s = DynamicStrings_Slice (s, 1, -1);
+    }
+  else if (((DynamicStrings_char (s, 0)) == '"') && ((DynamicStrings_char (s, -1)) == '"'))
+    {
+      /* avoid dangling else.  */
+      s = DynamicStrings_Slice (s, 1, -1);
+    }
+  return s;
+  /* static analysis guarentees a RETURN statement will be used before here.  */
+  __builtin_unreachable ();
+}
+
+
+/*
    getStringContents - return the string contents of a constant, literal,
                        string or a constexp node.
 */
@@ -7608,7 +7648,7 @@ static DynamicStrings_String getStringContents (decl_node__opaque n)
   else if (isString (n))
     {
       /* avoid dangling else.  */
-      return getString (n);
+      return getStringChar (n);
     }
   else if (isConstExp (n))
     {
@@ -7672,11 +7712,29 @@ static decl_node__opaque resolveString (decl_node__opaque n)
 
 
 /*
-   foldBinary -
+   addQuotes - adds delimiter quote char to string.
+*/
+
+static DynamicStrings_String addQuotes (DynamicStrings_String s, char quote)
+{
+  DynamicStrings_String qs;
+
+  s = DynamicStrings_ConCatChar (s, quote);
+  qs = DynamicStrings_InitStringChar (quote);
+  qs = DynamicStrings_ConCat (qs, DynamicStrings_Mark (s));
+  return qs;
+  /* static analysis guarentees a RETURN statement will be used before here.  */
+  __builtin_unreachable ();
+}
+
+
+/*
+   foldBinary - attempt to fold binary + for string constants.
 */
 
 static decl_node__opaque foldBinary (decl_nodeT k, decl_node__opaque l, decl_node__opaque r, decl_node__opaque res)
 {
+  char qc;
   decl_node__opaque n;
   DynamicStrings_String ls;
   DynamicStrings_String rs;
@@ -7686,7 +7744,12 @@ static decl_node__opaque foldBinary (decl_nodeT k, decl_node__opaque l, decl_nod
     {
       ls = getStringContents (l);
       rs = getStringContents (r);
+      qc = '\'';
+      /* Add unquoted contents.  */
       ls = DynamicStrings_Add (ls, rs);
+      /* Add quote.  */
+      ls = addQuotes (ls, qc);
+      /* Build new string.  */
       n = static_cast<decl_node__opaque> (decl_makeString (nameKey_makekey (DynamicStrings_string (ls))));
       ls = DynamicStrings_KillString (ls);
       rs = DynamicStrings_KillString (rs);
@@ -22789,7 +22852,7 @@ static decl_node__opaque doDupExpr (decl_node__opaque n)
         break;
 
       case decl_length:
-        M2RTS_HALT (-1);
+        M2RTS_HALT (-1);  /* length should have been converted into unary.  */
         __builtin_unreachable ();
         break;
 
diff --git a/gcc/m2/mc-boot/GmcFileName.h b/gcc/m2/mc-boot/GmcFileName.h
index 11f1512..6c7ec75 100644
--- a/gcc/m2/mc-boot/GmcFileName.h
+++ b/gcc/m2/mc-boot/GmcFileName.h
@@ -50,7 +50,7 @@ extern "C" {
                        given a module and an extension. This file name
                        length will be operating system specific.
                        String, Extension, is concatenated onto
-                       Module and thus it is safe to `Mark' the extension
+                       Module and thus it is safe to Mark the extension
                        for garbage collection.
 */
 
diff --git a/gcc/m2/mc/decl.mod b/gcc/m2/mc/decl.mod
index 342487e..197ca5e 100644
--- a/gcc/m2/mc/decl.mod
+++ b/gcc/m2/mc/decl.mod
@@ -4643,6 +4643,28 @@ END getLiteralStringContents ;
 
 
 (*
+   getStringChar - if the string is delimited by single
+                   or double quotes then strip both
+                   quotes from the string.
+*)
+
+PROCEDURE getStringChar (n: node) : String ;
+VAR
+   s: String ;
+BEGIN
+   s := getString (n) ;
+   IF (DynamicStrings.char (s, 0) = "'") AND (DynamicStrings.char (s, -1) = "'")
+   THEN
+      s := DynamicStrings.Slice (s, 1, -1)
+   ELSIF (DynamicStrings.char (s, 0) = '"') AND (DynamicStrings.char (s, -1) = '"')
+   THEN
+      s := DynamicStrings.Slice (s, 1, -1)
+   END ;
+   RETURN s
+END getStringChar ;
+
+
+(*
    getStringContents - return the string contents of a constant, literal,
                        string or a constexp node.
 *)
@@ -4657,7 +4679,7 @@ BEGIN
       RETURN getLiteralStringContents (n)
    ELSIF isString (n)
    THEN
-      RETURN getString (n)
+      RETURN getStringChar (n)
    ELSIF isConstExp (n)
    THEN
       RETURN getStringContents (n^.unaryF.arg)
@@ -4709,11 +4731,27 @@ END resolveString ;
 
 
 (*
-   foldBinary -
+   addQuotes - adds delimiter quote char to string.
+*)
+
+PROCEDURE addQuotes (s: String; quote: CHAR) : String ;
+VAR
+   qs: String ;
+BEGIN
+   s := DynamicStrings.ConCatChar (s, quote) ;
+   qs := DynamicStrings.InitStringChar (quote) ;
+   qs := DynamicStrings.ConCat (qs, DynamicStrings.Mark (s)) ;
+   RETURN qs
+END addQuotes ;
+
+
+(*
+   foldBinary - attempt to fold binary + for string constants.
 *)
 
 PROCEDURE foldBinary (k: nodeT; l, r: node; res: node) : node ;
 VAR
+   qc: CHAR ;
    n : node ;
    ls,
    rs: String ;
@@ -4723,7 +4761,12 @@ BEGIN
    THEN
       ls := getStringContents (l) ;
       rs := getStringContents (r) ;
+      qc := "'" ;
+      (* Add unquoted contents.  *)
       ls := DynamicStrings.Add (ls, rs) ;
+      (* Add quote.  *)
+      ls := addQuotes (ls, qc) ;
+      (* Build new string.  *)
       n := makeString (makekey (DynamicStrings.string (ls))) ;
       ls := DynamicStrings.KillString (ls) ;
       rs := DynamicStrings.KillString (rs)