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news: prepare for 3.5

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Akim Demaille
2019-12-10 07:06:04 +01:00
parent b3abe014f2
commit 57503e2165
1 changed files with 71 additions and 82 deletions
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NEWS
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@@ -2,8 +2,17 @@ GNU Bison NEWS
* Noteworthy changes in release ?.? (????-??-??) [?]
** Backward incompatible changes
* Noteworthy changes in release 3.4.92 (2019-12-08) [beta]
Lone carriage-return characters (aka \r or ^M) in the grammar files are no
longer treated as end-of-lines. This changes the diagnostics, and in
particular their locations.
In C++, line numbers and columns are now represented as 'int' not
'unsigned', so that integer overflow on positions is easily checkable via
'gcc -fsanitize=undefined' and the like. This affects the API for
positions. The default position and location classes now expose
'counter_type' (int), used to define line and column numbers.
** Deprecated features
@@ -11,7 +20,44 @@ GNU Bison NEWS
obsoleted long ago by %printer, introduced in Bison 1.50 (November 2002).
It is deprecated and its support will be removed eventually.
** New Features
** New features
*** Lookahead correction in C++
Contributed by Adrian Vogelsgesang.
The C++ deterministic skeleton (lalr1.cc) now supports LAC, via the
%define variable parse.lac.
*** Variable api.token.raw: Optimized token numbers (all skeletons)
In the generated parsers, tokens have two numbers: the "external" token
number as returned by yylex (which starts at 257), and the "internal"
symbol number (which starts at 3). Each time yylex is called, a table
lookup maps the external token number to the internal symbol number.
When the %define variable api.token.raw is set, tokens are assigned their
internal number, which saves one table lookup per token, and also saves
the generation of the mapping table.
The gain is typically moderate, but in extreme cases (very simple user
actions), a 10% improvement can be observed.
*** Generated parsers use better types for states
Stacks now use the best integral type for state numbers, instead of always
using 15 bits. As a result "small" parsers now have a smaller memory
footprint (they use 8 bits), and there is support for large automata (16
bits), and extra large (using int, i.e., typically 31 bits).
*** Generated parsers prefer signed integer types
Bison skeletons now prefer signed to unsigned integer types when either
will do, as the signed types are less error-prone and allow for better
checking with 'gcc -fsanitize=undefined'. Also, the types chosen are now
portable to unusual machines where char, short and int are all the same
width. On non-GNU platforms this may entail including <limits.h> and (if
available) <stdint.h> to define integer types and constants.
*** A skeleton for the D programming language
@@ -27,30 +73,12 @@ GNU Bison NEWS
The lalr1.d skeleton *is functional*, and works well, as demonstrated in
examples/d/calc.d. Please try it, enjoy it, and... commit to support it.
** Changes
*** Debug traces in Java
*** Debugging glr.c and glr.cc
The Java backend no longer emits code and data for parser tracing if the
%define variable parse.trace is not defined.
The glr.c skeleton always had asserts to check its own behavior (not the
user's). These assertions are now under the control of the parse.assert
%define variable (disabled by default).
*** Clean up
Several new compiler warnings in the generated output have been avoided.
Some unused features are no longer emitted. Cleaner generated code in
general.
** Bug Fixes
*** Crashes when reporting verbose error messages
In theory, parsers using %nonassoc could crash. This unlikely bug has been
fixed.
* Noteworthy changes in release 3.4.91 (2019-11-20) [beta]
** New Features
** Diagnostics
*** New diagnostic: -Wdangling-alias
@@ -101,7 +129,7 @@ GNU Bison NEWS
%%
expr:
gives, with -Wyacc
gives with -Wyacc
input.y:2.15-20: warning: POSIX yacc reserves %type to nonterminals [-Wyacc]
2 | %type <ival> TOKEN1 TOKEN2 't'
@@ -113,50 +141,9 @@ GNU Bison NEWS
2 | %type <ival> TOKEN1 TOKEN2 't'
| ^~~~~~
* Noteworthy changes in release 3.4.90 (2019-10-29) [beta]
** Backward incompatible changes
Lone carriage-return characters (aka \r or ^M) in the grammar files are no
longer treated as end-of-lines. This changes the diagnostics, and in
particular their locations.
In C++, line numbers and columns are now represented as 'int' not
'unsigned', so that integer overflow on positions is easily checkable via
'gcc -fsanitize=undefined' and the like. This affects the API for
positions. The default position and location classes now expose
'counter_type' (int), used to define line and column numbers.
** Bug fixes
In Java, %define api.prefix was ignored. It now behaves as expected.
** New features
*** Lookahead correction in C++
Contributed by Adrian Vogelsgesang.
The C++ deterministic skeleton (lalr1.cc) now supports LAC, via the
%define variable parse.lac.
*** Variable api.token.raw: Optimized token numbers (all skeletons)
In the generated parsers, tokens have two numbers: the "external" token
number as returned by yylex (which starts at 257), and the "internal"
symbol number (which starts at 3). Each time yylex is called, a table
lookup maps the external token number to the internal symbol number.
When the %define variable api.token.raw is set, tokens are assigned their
internal number, which saves one table lookup per token, and also saves
the generation of the mapping table.
The gain is typically moderate, but in extreme cases (very simple user
actions), a 10% improvement can be observed.
*** Diagnostics with insertion
The diagnostics now display suggestion below the underlined source.
The diagnostics now display the suggestion below the underlined source.
Replacement for undeclared symbols are now also suggested.
$ cat /tmp/foo.y
@@ -197,26 +184,28 @@ GNU Bison NEWS
1 | %token FOO …
| ^~~
*** Debug traces in Java
** Changes
The Java backend no longer emits code and data for parser tracing if the
%define variable parse.trace is not defined.
*** Debugging glr.c and glr.cc
*** Generated parsers prefer signed integer types
The glr.c skeleton always had asserts to check its own behavior (not the
user's). These assertions are now under the control of the parse.assert
%define variable (disabled by default).
Bison skeletons now prefer signed to unsigned integer types when either
will do, as the signed types are less error-prone and allow for better
checking with 'gcc -fsanitize=undefined'. Also, the types chosen are now
portable to unusual machines where char, short and int are all the same
width. On non-GNU platforms this may entail including <limits.h> and (if
available) <stdint.h> to define integer types and constants.
*** Clean up
*** Generated parsers use better types for states
Several new compiler warnings in the generated output have been avoided.
Some unused features are no longer emitted. Cleaner generated code in
general.
Stacks now use the best integral type for state numbers, instead of always
using 15 bits. As a result "small" parsers now have a smaller memory
footprint (they use 8 bits), and there is support for large automata (16
bits), and extra large (using int, i.e., typically 31 bits).
** Bug Fixes
Portability issues in the test suite.
In theory, parsers using %nonassoc could crash when reporting verbose
error messages. This unlikely bug has been fixed.
In Java, %define api.prefix was ignored. It now behaves as expected.
* Noteworthy changes in release 3.4.2 (2019-09-12) [stable]