Meilleures erreurs de syntaxe pour les parentheses mal fermees, etc

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@1689 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

17 files changed, 172 insertions, 44 deletions

diff --git a/.depend b/.depend
index a397caeac..1dacd1217 100644
--- a/.depend
+++ b/.depend
@@ -15,11 +15,12 @@ utils/tbl.cmx: utils/tbl.cmi
 utils/terminfo.cmo: utils/terminfo.cmi 
 utils/terminfo.cmx: utils/terminfo.cmi 
 parsing/lexer.cmi: parsing/parser.cmi 
-parsing/parse.cmi: parsing/parsetree.cmi 
+parsing/parse.cmi: parsing/parsetree.cmi parsing/syntaxerr.cmi 
 parsing/parser.cmi: parsing/parsetree.cmi 
 parsing/parsetree.cmi: parsing/asttypes.cmi parsing/location.cmi \
     parsing/longident.cmi 
 parsing/pstream.cmi: parsing/parsetree.cmi 
+parsing/syntaxerr.cmi: parsing/location.cmi 
 parsing/lexer.cmo: utils/misc.cmi parsing/parser.cmi parsing/lexer.cmi 
 parsing/lexer.cmx: utils/misc.cmx parsing/parser.cmx parsing/lexer.cmi 
 parsing/linenum.cmo: utils/misc.cmi parsing/linenum.cmi 
@@ -31,9 +32,9 @@ parsing/location.cmx: parsing/linenum.cmx utils/terminfo.cmx \
 parsing/longident.cmo: utils/misc.cmi parsing/longident.cmi 
 parsing/longident.cmx: utils/misc.cmx parsing/longident.cmi 
 parsing/parse.cmo: parsing/lexer.cmi parsing/location.cmi parsing/parser.cmi \
-    parsing/parse.cmi 
+    parsing/syntaxerr.cmi parsing/parse.cmi 
 parsing/parse.cmx: parsing/lexer.cmx parsing/location.cmx parsing/parser.cmx \
-    parsing/parse.cmi 
+    parsing/syntaxerr.cmx parsing/parse.cmi 
 parsing/parser.cmo: parsing/asttypes.cmi utils/clflags.cmo \
     parsing/location.cmi parsing/longident.cmi parsing/parsetree.cmi \
     parsing/pstream.cmi parsing/parser.cmi 
@@ -44,6 +45,8 @@ parsing/pstream.cmo: parsing/asttypes.cmi parsing/location.cmi \
     parsing/longident.cmi parsing/parsetree.cmi parsing/pstream.cmi 
 parsing/pstream.cmx: parsing/asttypes.cmi parsing/location.cmx \
     parsing/longident.cmx parsing/parsetree.cmi parsing/pstream.cmi 
+parsing/syntaxerr.cmo: parsing/location.cmi parsing/syntaxerr.cmi 
+parsing/syntaxerr.cmx: parsing/location.cmx parsing/syntaxerr.cmi 
 typing/btype.cmi: typing/path.cmi typing/types.cmi 
 typing/ctype.cmi: parsing/asttypes.cmi typing/env.cmi typing/ident.cmi \
     typing/types.cmi 
@@ -361,8 +364,6 @@ asmcomp/selectgen.cmi: asmcomp/arch.cmo asmcomp/cmm.cmi typing/ident.cmi \
 asmcomp/selection.cmi: asmcomp/cmm.cmi asmcomp/mach.cmi 
 asmcomp/spill.cmi: asmcomp/mach.cmi 
 asmcomp/split.cmi: asmcomp/mach.cmi 
-asmcomp/arch.cmo: utils/config.cmi 
-asmcomp/arch.cmx: utils/config.cmx 
 asmcomp/asmgen.cmo: utils/clflags.cmo asmcomp/closure.cmi asmcomp/cmm.cmi \
     asmcomp/cmmgen.cmi asmcomp/coloring.cmi utils/config.cmi asmcomp/emit.cmi \
     asmcomp/emitaux.cmi asmcomp/interf.cmi asmcomp/linearize.cmi \
@@ -435,12 +436,12 @@ asmcomp/compilenv.cmx: asmcomp/clambda.cmx utils/config.cmx typing/env.cmx \
     typing/ident.cmx utils/misc.cmx asmcomp/compilenv.cmi 
 asmcomp/emit.cmo: asmcomp/arch.cmo asmcomp/cmm.cmi asmcomp/compilenv.cmi \
     utils/config.cmi asmcomp/emitaux.cmi asmcomp/linearize.cmi \
-    parsing/location.cmi asmcomp/mach.cmi utils/misc.cmi utils/nativeint.cmi \
-    asmcomp/proc.cmi asmcomp/reg.cmi asmcomp/emit.cmi 
+    asmcomp/mach.cmi utils/misc.cmi utils/nativeint.cmi asmcomp/proc.cmi \
+    asmcomp/reg.cmi asmcomp/emit.cmi 
 asmcomp/emit.cmx: asmcomp/arch.cmx asmcomp/cmm.cmx asmcomp/compilenv.cmx \
     utils/config.cmx asmcomp/emitaux.cmx asmcomp/linearize.cmx \
-    parsing/location.cmx asmcomp/mach.cmx utils/misc.cmx utils/nativeint.cmx \
-    asmcomp/proc.cmx asmcomp/reg.cmx asmcomp/emit.cmi 
+    asmcomp/mach.cmx utils/misc.cmx utils/nativeint.cmx asmcomp/proc.cmx \
+    asmcomp/reg.cmx asmcomp/emit.cmi 
 asmcomp/emitaux.cmo: utils/nativeint.cmi asmcomp/emitaux.cmi 
 asmcomp/emitaux.cmx: utils/nativeint.cmx asmcomp/emitaux.cmi 
 asmcomp/interf.cmo: asmcomp/mach.cmi asmcomp/proc.cmi asmcomp/reg.cmi \
@@ -479,8 +480,10 @@ asmcomp/proc.cmx: asmcomp/arch.cmx utils/ccomp.cmx asmcomp/cmm.cmx \
     asmcomp/mach.cmx utils/misc.cmx asmcomp/reg.cmx asmcomp/proc.cmi 
 asmcomp/reg.cmo: asmcomp/cmm.cmi asmcomp/reg.cmi 
 asmcomp/reg.cmx: asmcomp/cmm.cmx asmcomp/reg.cmi 
-asmcomp/reload.cmo: asmcomp/reloadgen.cmi asmcomp/reload.cmi 
-asmcomp/reload.cmx: asmcomp/reloadgen.cmx asmcomp/reload.cmi 
+asmcomp/reload.cmo: asmcomp/arch.cmo asmcomp/cmm.cmi asmcomp/mach.cmi \
+    asmcomp/reg.cmi asmcomp/reloadgen.cmi asmcomp/reload.cmi 
+asmcomp/reload.cmx: asmcomp/arch.cmx asmcomp/cmm.cmx asmcomp/mach.cmx \
+    asmcomp/reg.cmx asmcomp/reloadgen.cmx asmcomp/reload.cmi 
 asmcomp/reloadgen.cmo: asmcomp/mach.cmi utils/misc.cmi asmcomp/reg.cmi \
     asmcomp/reloadgen.cmi 
 asmcomp/reloadgen.cmx: asmcomp/mach.cmx utils/misc.cmx asmcomp/reg.cmx \
@@ -489,10 +492,8 @@ asmcomp/schedgen.cmo: asmcomp/arch.cmo asmcomp/cmm.cmi asmcomp/linearize.cmi \
     asmcomp/mach.cmi utils/misc.cmi asmcomp/reg.cmi asmcomp/schedgen.cmi 
 asmcomp/schedgen.cmx: asmcomp/arch.cmx asmcomp/cmm.cmx asmcomp/linearize.cmx \
     asmcomp/mach.cmx utils/misc.cmx asmcomp/reg.cmx asmcomp/schedgen.cmi 
-asmcomp/scheduling.cmo: asmcomp/arch.cmo asmcomp/mach.cmi \
-    asmcomp/schedgen.cmi asmcomp/scheduling.cmi 
-asmcomp/scheduling.cmx: asmcomp/arch.cmx asmcomp/mach.cmx \
-    asmcomp/schedgen.cmx asmcomp/scheduling.cmi 
+asmcomp/scheduling.cmo: asmcomp/schedgen.cmi asmcomp/scheduling.cmi 
+asmcomp/scheduling.cmx: asmcomp/schedgen.cmx asmcomp/scheduling.cmi 
 asmcomp/selectgen.cmo: asmcomp/arch.cmo asmcomp/cmm.cmi typing/ident.cmi \
     asmcomp/mach.cmi utils/misc.cmi utils/nativeint.cmi asmcomp/proc.cmi \
     asmcomp/reg.cmi utils/tbl.cmi asmcomp/selectgen.cmi 
@@ -500,10 +501,10 @@ asmcomp/selectgen.cmx: asmcomp/arch.cmx asmcomp/cmm.cmx typing/ident.cmx \
     asmcomp/mach.cmx utils/misc.cmx utils/nativeint.cmx asmcomp/proc.cmx \
     asmcomp/reg.cmx utils/tbl.cmx asmcomp/selectgen.cmi 
 asmcomp/selection.cmo: asmcomp/arch.cmo asmcomp/cmm.cmi asmcomp/mach.cmi \
-    utils/misc.cmi asmcomp/reg.cmi asmcomp/selectgen.cmi \
+    utils/misc.cmi asmcomp/proc.cmi asmcomp/reg.cmi asmcomp/selectgen.cmi \
     asmcomp/selection.cmi 
 asmcomp/selection.cmx: asmcomp/arch.cmx asmcomp/cmm.cmx asmcomp/mach.cmx \
-    utils/misc.cmx asmcomp/reg.cmx asmcomp/selectgen.cmx \
+    utils/misc.cmx asmcomp/proc.cmx asmcomp/reg.cmx asmcomp/selectgen.cmx \
     asmcomp/selection.cmi 
 asmcomp/spill.cmo: asmcomp/mach.cmi asmcomp/proc.cmi asmcomp/reg.cmi \
     asmcomp/spill.cmi 
@@ -527,13 +528,13 @@ driver/compile.cmx: bytecomp/bytegen.cmx utils/ccomp.cmx utils/clflags.cmx \
     typing/typedtree.cmx typing/typemod.cmx driver/compile.cmi 
 driver/errors.cmo: bytecomp/bytelibrarian.cmi bytecomp/bytelink.cmi \
     typing/env.cmi typing/includemod.cmi parsing/lexer.cmi \
-    parsing/location.cmi parsing/parse.cmi bytecomp/symtable.cmi \
+    parsing/location.cmi bytecomp/symtable.cmi parsing/syntaxerr.cmi \
     bytecomp/translcore.cmi typing/typeclass.cmi typing/typecore.cmi \
     typing/typedecl.cmi typing/typemod.cmi typing/typetexp.cmi \
     driver/errors.cmi 
 driver/errors.cmx: bytecomp/bytelibrarian.cmx bytecomp/bytelink.cmx \
     typing/env.cmx typing/includemod.cmx parsing/lexer.cmx \
-    parsing/location.cmx parsing/parse.cmx bytecomp/symtable.cmx \
+    parsing/location.cmx bytecomp/symtable.cmx parsing/syntaxerr.cmx \
     bytecomp/translcore.cmx typing/typeclass.cmx typing/typecore.cmx \
     typing/typedecl.cmx typing/typemod.cmx typing/typetexp.cmx \
     driver/errors.cmi 
@@ -556,13 +557,13 @@ driver/optcompile.cmx: asmcomp/asmgen.cmx utils/ccomp.cmx utils/clflags.cmx \
 driver/opterrors.cmo: asmcomp/asmgen.cmi asmcomp/asmlibrarian.cmi \
     asmcomp/asmlink.cmi asmcomp/compilenv.cmi typing/env.cmi \
     typing/includemod.cmi parsing/lexer.cmi parsing/location.cmi \
-    parsing/parse.cmi bytecomp/translcore.cmi typing/typeclass.cmi \
+    parsing/syntaxerr.cmi bytecomp/translcore.cmi typing/typeclass.cmi \
     typing/typecore.cmi typing/typedecl.cmi typing/typemod.cmi \
     typing/typetexp.cmi driver/opterrors.cmi 
 driver/opterrors.cmx: asmcomp/asmgen.cmx asmcomp/asmlibrarian.cmx \
     asmcomp/asmlink.cmx asmcomp/compilenv.cmx typing/env.cmx \
     typing/includemod.cmx parsing/lexer.cmx parsing/location.cmx \
-    parsing/parse.cmx bytecomp/translcore.cmx typing/typeclass.cmx \
+    parsing/syntaxerr.cmx bytecomp/translcore.cmx typing/typeclass.cmx \
     typing/typecore.cmx typing/typedecl.cmx typing/typemod.cmx \
     typing/typetexp.cmx driver/opterrors.cmi 
 driver/optmain.cmo: asmcomp/asmlibrarian.cmi asmcomp/asmlink.cmi \
diff --git a/Makefile b/Makefile
index 7833fb116..ffd35c77e 100644
--- a/Makefile
+++ b/Makefile
@@ -23,7 +23,8 @@ UTILS=utils/misc.cmo utils/tbl.cmo utils/config.cmo \
 OPTUTILS=$(UTILS) utils/nativeint.cmo
 
 PARSING=parsing/linenum.cmo parsing/location.cmo parsing/longident.cmo \
-  parsing/pstream.cmo parsing/parser.cmo parsing/lexer.cmo parsing/parse.cmo
+  parsing/syntaxerr.cmo parsing/pstream.cmo parsing/parser.cmo \
+  parsing/lexer.cmo parsing/parse.cmo
 
 TYPING=typing/ident.cmo typing/path.cmo \
   typing/primitive.cmo typing/types.cmo \
diff --git a/Makefile.Mac b/Makefile.Mac
index 9cca910f4..3a5636919 100644
--- a/Makefile.Mac
+++ b/Makefile.Mac
@@ -19,8 +19,8 @@ UTILS = :utils:misc.cmo :utils:tbl.cmo :utils:config.cmo ¶
         :utils:clflags.cmo :utils:terminfo.cmo :utils:ccomp.cmo
 
 PARSING = :parsing:linenum.cmo :parsing:location.cmo :parsing:longident.cmo ¶
-          :parsing:pstream.cmo :parsing:parser.cmo :parsing:lexer.cmo ¶
-          :parsing:parse.cmo
+          :parsing:syntaxerr.cmo :parsing:pstream.cmo :parsing:parser.cmo ¶
+          :parsing:lexer.cmo :parsing:parse.cmo
 
 TYPING = :typing:ident.cmo :typing:path.cmo ¶
   :typing:primitive.cmo :typing:types.cmo ¶
diff --git a/Makefile.nt b/Makefile.nt
index 872ab87d6..1d5705f78 100644
--- a/Makefile.nt
+++ b/Makefile.nt
@@ -21,7 +21,8 @@ UTILS=utils\misc.cmo utils\tbl.cmo utils\config.cmo \
 OPTUTILS=$(UTILS) utils\nativeint.cmo
 
 PARSING=parsing\linenum.cmo parsing\location.cmo parsing\longident.cmo \
-  parsing\pstream.cmo parsing\parser.cmo parsing\lexer.cmo parsing\parse.cmo
+  parsing\syntaxerr.cmo parsing\pstream.cmo parsing\parser.cmo \
+  parsing\lexer.cmo parsing\parse.cmo
 
 TYPING=typing\ident.cmo typing\path.cmo \
   typing\primitive.cmo typing\types.cmo \
diff --git a/driver/compile.ml b/driver/compile.ml
index 285db4743..d79101792 100644
--- a/driver/compile.ml
+++ b/driver/compile.ml
@@ -77,7 +77,7 @@ let parse_file inputfile parse_fun ast_magic =
       else false
     with
       Outdated_version ->
-        failwith "Ocaml and preprocessor have incompatible versions"
+        fatal_error "Ocaml and preprocessor have incompatible versions"
     | _ -> false
   in
   let ast =
diff --git a/driver/errors.ml b/driver/errors.ml
index c93f6f3eb..6b032f782 100644
--- a/driver/errors.ml
+++ b/driver/errors.ml
@@ -24,9 +24,8 @@ let report_error exn =
     Lexer.Error(err, start, stop) ->
       Location.print {loc_start = start; loc_end = stop};
       Lexer.report_error err
-  | Parse.Error(start, stop) ->
-      Location.print {loc_start = start; loc_end = stop};
-      print_string "Syntax error"
+  | Syntaxerr.Error err ->
+      Syntaxerr.report_error err
   | Env.Error err ->
       Env.report_error err
   | Typecore.Error(loc, err) ->
diff --git a/driver/optcompile.ml b/driver/optcompile.ml
index 7d1e67a94..897f03910 100644
--- a/driver/optcompile.ml
+++ b/driver/optcompile.ml
@@ -74,7 +74,7 @@ let parse_file inputfile parse_fun ast_magic =
       else false
     with
       Outdated_version ->
-        failwith "Ocaml and preprocessor have incompatible versions"
+        fatal_error "Ocaml and preprocessor have incompatible versions"
     | _ -> false
   in
   let ast =
diff --git a/driver/opterrors.ml b/driver/opterrors.ml
index 01b3f4dd4..a5910355d 100644
--- a/driver/opterrors.ml
+++ b/driver/opterrors.ml
@@ -24,9 +24,8 @@ let report_error exn =
     Lexer.Error(err, start, stop) ->
       Location.print {loc_start = start; loc_end = stop};
       Lexer.report_error err
-  | Parse.Error(start, stop) ->
-      Location.print {loc_start = start; loc_end = stop};
-      print_string "Syntax error"
+  | Syntaxerr.Error err ->
+      Syntaxerr.report_error err
   | Env.Error err ->
       Env.report_error err
   | Typecore.Error(loc, err) ->
diff --git a/parsing/parse.ml b/parsing/parse.ml
index 02a9a56fa..a04571f01 100644
--- a/parsing/parse.ml
+++ b/parsing/parse.ml
@@ -13,7 +13,8 @@
 
 (* Entry points in the parser *)
 
-exception Error of int * int        (* Syntax error *)
+open Location
+
 (* Skip tokens to the end of the phrase *)
 
 let rec skip_phrase lexbuf =
@@ -43,12 +44,15 @@ let wrap parsing_fun lexbuf =
     | Lexer.Error(_, _, _) as err ->
         if !Location.input_name = "" then skip_phrase lexbuf;
         raise err
+    | Syntaxerr.Error _ as err ->
+        if !Location.input_name = "" then maybe_skip_phrase lexbuf;
+        raise err
     | Parsing.Parse_error ->
-        let start = Lexing.lexeme_start lexbuf
-        and stop  = Lexing.lexeme_end lexbuf in
+        let loc = { loc_start = Lexing.lexeme_start lexbuf;
+                    loc_end = Lexing.lexeme_end lexbuf } in
         if !Location.input_name = "" 
         then maybe_skip_phrase lexbuf;
-        raise(Error(start, stop))
+        raise(Syntaxerr.Error(Syntaxerr.Other loc))
 
 let implementation = wrap Parser.implementation
 and interface = wrap Parser.interface
diff --git a/parsing/parse.mli b/parsing/parse.mli
index ddd58daa1..2becb1271 100644
--- a/parsing/parse.mli
+++ b/parsing/parse.mli
@@ -18,4 +18,3 @@ val interface : Lexing.lexbuf -> Parsetree.signature
 val toplevel_phrase : Lexing.lexbuf -> Parsetree.toplevel_phrase
 val use_file : Lexing.lexbuf -> Parsetree.toplevel_phrase list
 
-exception Error of int * int        (* Syntax error *)
diff --git a/parsing/parser.mly b/parsing/parser.mly
index 79a5ef3cf..74c90f1e7 100644
--- a/parsing/parser.mly
+++ b/parsing/parser.mly
@@ -96,6 +96,10 @@ let rec mkrangepat c1 c2 =
   mkpat(Ppat_or(mkpat(Ppat_constant(Const_char c1)),
                 mkrangepat (Char.chr(Char.code c1 + 1)) c2))
 
+let unclosed opening_name opening_num closing_name closing_num =
+  raise(Syntaxerr.Error(Syntaxerr.Unclosed(rhs_loc opening_num, opening_name,
+                                           rhs_loc closing_num, closing_name)))
+
 %}
 
 /* Tokens */
@@ -277,15 +281,23 @@ module_expr:
       { mkmod(Pmod_ident $1) }
   | STRUCT structure END
       { mkmod(Pmod_structure($2)) }
+  | STRUCT structure error
+      { unclosed "struct" 1 "end" 3 }
   | FUNCTOR LPAREN UIDENT COLON module_type RPAREN MINUSGREATER module_expr
     %prec prec_fun
       { mkmod(Pmod_functor($3, $5, $8)) }
   | module_expr LPAREN module_expr RPAREN
       { mkmod(Pmod_apply($1, $3)) }
+  | module_expr LPAREN module_expr error
+      { unclosed "(" 2 ")" 4 }
   | LPAREN module_expr COLON module_type RPAREN
       { mkmod(Pmod_constraint($2, $4)) }
+  | LPAREN module_expr COLON module_type error
+      { unclosed "(" 1 ")" 5 }
   | LPAREN module_expr RPAREN
       { $2 }
+  | LPAREN module_expr error
+      { unclosed "(" 1 ")" 3 }
 ;
 structure:
     structure_tail                              { $1 }
@@ -317,6 +329,8 @@ structure_item:
       { mkstr(Pstr_open $2) }
   | CLASS class_list END
       { mkstr(Pstr_class (List.rev $2)) }
+  | CLASS class_list error
+      { unclosed "class" 1 "end" 3 }
 ;
 module_binding:
     EQUAL module_expr
@@ -334,6 +348,8 @@ module_type:
       { mkmty(Pmty_ident $1) }
   | SIG signature END
       { mkmty(Pmty_signature(List.rev $2)) }
+  | SIG signature error
+      { unclosed "sig" 1 "end" 3 }
   | FUNCTOR LPAREN UIDENT COLON module_type RPAREN MINUSGREATER module_type
     %prec prec_fun
       { mkmty(Pmty_functor($3, $5, $8)) }
@@ -341,6 +357,8 @@ module_type:
       { mkmty(Pmty_with($1, List.rev $3)) }
   | LPAREN module_type RPAREN
       { $2 }
+  | LPAREN module_type error
+      { unclosed "(" 1 ")" 3 }
 ;
 signature:
     /* empty */                                 { [] }
@@ -391,6 +409,8 @@ expr:
       { mkexp(Pexp_apply($1, List.rev $2)) }
   | LET rec_flag let_bindings IN seq_expr %prec prec_let
       { mkexp(Pexp_let($2, List.rev $3, $5)) }
+  | LET rec_flag let_bindings error %prec prec_let
+      { unclosed "let" 1 "in" 4 }
   | PARSER opt_pat opt_bar parser_cases %prec prec_fun
       { Pstream.cparser ($2, List.rev $4) }
   | FUNCTION opt_bar match_cases %prec prec_fun
@@ -403,6 +423,8 @@ expr:
       { mkexp(Pexp_apply(Pstream.cparser ($5, List.rev $7), [$2])) }
   | TRY seq_expr WITH opt_bar match_cases %prec prec_try
       { mkexp(Pexp_try($2, List.rev $5)) }
+  | TRY seq_expr error %prec prec_try
+      { unclosed "try" 1 "with" 3 }
   | expr_comma_list
       { mkexp(Pexp_tuple(List.rev $1)) }
   | constr_longident simple_expr %prec prec_constr_appl
@@ -413,8 +435,12 @@ expr:
       { mkexp(Pexp_ifthenelse($2, $4, None)) }
   | WHILE seq_expr DO seq_expr DONE
       { mkexp(Pexp_while($2, $4)) }
+  | WHILE seq_expr DO seq_expr error
+      { unclosed "while" 1 "done" 5 }
   | FOR val_ident EQUAL seq_expr direction_flag seq_expr DO seq_expr DONE
       { mkexp(Pexp_for($2, $4, $6, $5, $8)) }
+  | FOR val_ident EQUAL seq_expr direction_flag seq_expr DO seq_expr error
+      { unclosed "for" 1 "done" 9 }
   | expr COLONCOLON expr
       { mkexp(Pexp_construct(Lident "::", Some(mkexp(Pexp_tuple[$1;$3])), false)) }
   | expr INFIXOP0 expr
@@ -471,30 +497,48 @@ simple_expr:
       { mkexp(Pexp_construct($1, None, false)) }
   | LPAREN seq_expr RPAREN
       { $2 }
+  | LPAREN seq_expr error
+      { unclosed "(" 1 ")" 3 }
   | BEGIN seq_expr END
       { $2 }
+  | BEGIN seq_expr error
+      { unclosed "begin" 1 "end" 3 }
   | LPAREN seq_expr type_constraint RPAREN
       { let (t, t') = $3 in mkexp(Pexp_constraint($2, t, t')) }
+  | LPAREN seq_expr type_constraint error
+      { unclosed "(" 1 ")" 4 }
   | simple_expr DOT label_longident
       { mkexp(Pexp_field($1, $3)) }
   | simple_expr DOT LPAREN seq_expr RPAREN
       { mkexp(Pexp_apply(mkexp(Pexp_ident(array_function "Array" "get")),
                          [$1; $4])) }
+  | simple_expr DOT LPAREN seq_expr error
+      { unclosed "(" 3 ")" 5 }
   | simple_expr DOT LBRACKET seq_expr RBRACKET
       { mkexp(Pexp_apply(mkexp(Pexp_ident(array_function "String" "get")),
                          [$1; $4])) }
+  | simple_expr DOT LBRACKET seq_expr error
+      { unclosed "[" 3 "]" 5 }
   | LBRACE lbl_expr_list opt_semi RBRACE
       { mkexp(Pexp_record(List.rev $2)) }
+  | LBRACE lbl_expr_list opt_semi error
+      { unclosed "{" 1 "}" 4 }
   | LBRACKETLESS stream_expr opt_semi GREATERRBRACKET
       { Pstream.cstream (List.rev $2) }
+  | LBRACKETLESS stream_expr opt_semi error
+      { unclosed "[<" 1 ">]" 4 }
   | LBRACKETLESS GREATERRBRACKET
       { Pstream.cstream [] }
   | LBRACKETBAR expr_semi_list opt_semi BARRBRACKET
       { mkexp(Pexp_array(List.rev $2)) }
+  | LBRACKETBAR expr_semi_list opt_semi error
+      { unclosed "[|" 1 "|]" 4 }
   | LBRACKETBAR BARRBRACKET
       { mkexp(Pexp_array []) }
   | LBRACKET expr_semi_list opt_semi RBRACKET
       { mklistexp(List.rev $2) }
+  | LBRACKET expr_semi_list opt_semi error
+      { unclosed "[" 1 "]" 4 }
   | PREFIXOP simple_expr
       { mkexp(Pexp_apply(mkoperator $1 1, [$2])) }
   | simple_expr SHARP label
@@ -503,6 +547,8 @@ simple_expr:
       { mkexp(Pexp_new($2)) }
   | LBRACELESS label_expr_list opt_semi GREATERRBRACE
       { mkexp(Pexp_override(List.rev $2)) }
+  | LBRACELESS label_expr_list opt_semi error
+      { unclosed "{<" 1 ">}" 4 }
   | LBRACELESS GREATERRBRACE
       { mkexp(Pexp_override []) }
   | LPAREN SHARP label RPAREN
@@ -541,6 +587,8 @@ parser_case:
     LBRACKETLESS stream_pattern opt_semi GREATERRBRACKET opt_pat
     MINUSGREATER seq_expr
       { (List.rev $2, $5, $7) }
+  | LBRACKETLESS stream_pattern opt_semi error
+      { unclosed "[<" 1 ">]" 4 }
   | LBRACKETLESS GREATERRBRACKET opt_pat MINUSGREATER seq_expr
       { ([], $3, $5) }
 ;
@@ -642,12 +690,20 @@ simple_pattern:
       { mkpat(Ppat_construct($1, None, false)) }
   | LBRACE lbl_pattern_list opt_semi RBRACE
       { mkpat(Ppat_record(List.rev $2)) }
+  | LBRACE lbl_pattern_list opt_semi error
+      { unclosed "{" 1 "}" 4 }
   | LBRACKET pattern_semi_list opt_semi RBRACKET
       { mklistpat(List.rev $2) }
+  | LBRACKET pattern_semi_list opt_semi error
+      { unclosed "{" 1 "}" 4 }
   | LPAREN pattern RPAREN
       { $2 }
+  | LPAREN pattern error
+      { unclosed "(" 1 ")" 3 }
   | LPAREN pattern COLON core_type RPAREN
       { mkpat(Ppat_constraint($2, $4)) }
+  | LPAREN pattern COLON core_type error
+      { unclosed "(" 1 ")" 5 }
 ;
 
 pattern_comma_list:
diff --git a/parsing/syntaxerr.ml b/parsing/syntaxerr.ml
new file mode 100644
index 000000000..6b87819b0
--- /dev/null
+++ b/parsing/syntaxerr.ml
@@ -0,0 +1,47 @@
+(***********************************************************************)
+(*                                                                     *)
+(*                           Objective Caml                            *)
+(*                                                                     *)
+(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
+(*                                                                     *)
+(*  Copyright 1997 Institut National de Recherche en Informatique et   *)
+(*  Automatique.  Distributed only by permission.                      *)
+(*                                                                     *)
+(***********************************************************************)
+
+(* $Id$ *)
+
+(* Auxiliary type for reporting syntax errors *)
+
+open Format
+
+type error =
+    Unclosed of Location.t * string * Location.t * string
+  | Other of Location.t
+
+exception Error of error
+
+let report_error = function
+    Unclosed(opening_loc, opening, closing_loc, closing) ->
+      if String.length !Location.input_name > 0 then begin
+        Location.print closing_loc;
+        print_string "Syntax error: missing '";
+        print_string closing;
+        print_string "'"; force_newline();
+        Location.print opening_loc;
+        print_string "This is the location of the unmatched '";
+        print_string opening;
+        print_string "'"
+      end else begin
+        Location.print opening_loc;
+        print_string "Syntax error: this '";
+        print_string opening;
+        print_string "' has no matching '";
+        print_string closing;
+        print_string "'"
+      end
+  | Other loc ->
+      Location.print loc;
+      print_string "Syntax error"
+
+
diff --git a/parsing/syntaxerr.mli b/parsing/syntaxerr.mli
new file mode 100644
index 000000000..dd69c8551
--- /dev/null
+++ b/parsing/syntaxerr.mli
@@ -0,0 +1,22 @@
+(***********************************************************************)
+(*                                                                     *)
+(*                           Objective Caml                            *)
+(*                                                                     *)
+(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
+(*                                                                     *)
+(*  Copyright 1997 Institut National de Recherche en Informatique et   *)
+(*  Automatique.  Distributed only by permission.                      *)
+(*                                                                     *)
+(***********************************************************************)
+
+(* $Id$ *)
+
+(* Auxiliary type for reporting syntax errors *)
+
+type error =
+    Unclosed of Location.t * string * Location.t * string
+  | Other of Location.t
+
+exception Error of error
+
+val report_error: error -> unit
diff --git a/tools/Makefile b/tools/Makefile
index 017738958..3dc8800b8 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -35,7 +35,7 @@ beforedepend:: ocamldep.ml
 CSLPROF=ocamlprof.cmo
 CSLPROF_IMPORTS=misc.cmo config.cmo clflags.cmo terminfo.cmo \
   linenum.cmo location.cmo longident.cmo pstream.cmo \
-  parser.cmo lexer.cmo parse.cmo
+  syntaxerr.cmo parser.cmo lexer.cmo parse.cmo
 
 ocamlprof: $(CSLPROF) profiling.cmo
 	$(CAMLC) $(LINKFLAGS) -o ocamlprof $(CSLPROF_IMPORTS) $(CSLPROF)
diff --git a/tools/Makefile.Mac b/tools/Makefile.Mac
index 154901a84..19f8647b2 100644
--- a/tools/Makefile.Mac
+++ b/tools/Makefile.Mac
@@ -33,7 +33,7 @@ beforedepend ÄÄ ocamldep
 #CSLPROF = ocamlprof.cmo
 #CSLPROF_IMPORTS = misc.cmo config.cmo clflags.cmo terminfo.cmo ¶
 #  linenum.cmo location.cmo longident.cmo pstream.cmo ¶
-#  parser.cmo lexer.cmo parse.cmo
+#  syntaxerr.cmo parser.cmo lexer.cmo parse.cmo
 #
 #ocamlprof Ä {CSLPROF} profiling.cmo
 #   {CAMLC} {LINKFLAGS} -o ocamlprof {CSLPROF_IMPORTS} {CSLPROF}
diff --git a/tools/Makefile.nt b/tools/Makefile.nt
index 135e42792..cf3a42d81 100644
--- a/tools/Makefile.nt
+++ b/tools/Makefile.nt
@@ -35,7 +35,7 @@ beforedepend:: ocamldep.ml
 CSLPROF=ocamlprof.cmo
 CSLPROF_IMPORTS=misc.cmo config.cmo clflags.cmo terminfo.cmo \
   linenum.cmo location.cmo longident.cmo pstream.cmo \
-  parser.cmo lexer.cmo parse.cmo
+  syntaxerr.cmo parser.cmo lexer.cmo parse.cmo
 
 ocamlprof: $(CSLPROF) profiling.cmo
 	$(CAMLC) $(LINKFLAGS) -o ocamlprof $(CSLPROF_IMPORTS) $(CSLPROF)
diff --git a/tools/ocamlprof.ml b/tools/ocamlprof.ml
index a5ee31f5a..7011e3f97 100644
--- a/tools/ocamlprof.ml
+++ b/tools/ocamlprof.ml
@@ -376,9 +376,8 @@ let main () =
       Lexer.Error(err, start, stop) ->
         Location.print {loc_start = start; loc_end = stop};
         Lexer.report_error err
-    | Parse.Error(start, stop) ->
-        Location.print {loc_start = start; loc_end = stop};
-        print_string "Syntax error"
+    | Syntaxerr.Error err ->
+        Syntaxerr.report_error err
     | Profiler msg ->
         print_string msg
     | Inversion(pos, next) ->