Currently deferred reductions are not "verbose" at all: only immediate
reductions are displayed in the YYDEBUG traces. I don't understand
why. Besides it seems actually simpler the install the reduction
traces right around the user action inside yyuserAction rather that
around calls to yyuserAction.
This only trouble is that yyuserAction does not know the stack number
it works on, so we have to pass it. And pass -1 when we are actually
running on a temporary stack.
The glr example, on "T(x) + y;" as input, adds these logs, which
allow to see when the `<cast>` is built:
Stack 0 Entering state 26
Reduced stack 0 by rule 7 (line 108); action deferred. Now in state 7.
Stack 0 Entering state 7
Reading a token
Next token is token '+' (1.6: )
Stack 1 Entering state 27
Reduced stack 1 by rule 13 (line 123); action deferred. Now in state 12.
Stack 1 Entering state 12
Next token is token '+' (1.6: )
Stack 1 dies.
Removing dead stacks.
On stack 0, shifting token '+' (1.6: )
Stack 0 now in state #14
+Reducing stack -1 by rule 6 (line 107):
+ $1 = token identifier (1.3: x)
+-> $$ = nterm expr (1.3: x)
+Reducing stack -1 by rule 7 (line 108):
+ $1 = token typename (1.0: T)
+ $2 = token '(' (1.2: )
+ $3 = nterm expr (1.3: x)
+ $4 = token ')' (1.4: )
+-> $$ = nterm expr (1.0-3: <cast>(x,T))
Returning to deterministic operation.
* data/skeletons/glr.c (yyuserAction): Take yyk as a new argument.
Rename argument yyn as yyrule for clarity.
Log before and after the user action.
Adjust callers to not call YY_REDUCE_PRINT and YY_SYMBOL_PRINT.
The next commit wants to use YY_REDUCE_PRINT above its current
definition. Move it higher.
* data/skeletons/glr.c (yylhsNonterm, YY_REDUCE_PRINT): Make available
earlier.
Reported by Jot Dot.
https://lists.gnu.org/r/help-bison/2020-12/msg00014.html
* data/skeletons/glr.c, data/skeletons/glr2.cc (b4_call_merger): Use
the symbol's slot, not its type.
* examples/c/glr/c++-types.y: Use explicit per-symbol typing together
with api.value.type=union.
(yylex): Use yytoken_kind_t.
Don't generate C code from bison, leave that to the skeletons.
* src/output.c (merger_output): Emit invocations to b4_call_merger.
* data/skeletons/glr.c, data/skeletons/glr2.cc (b4_call_merger): New.
Now that the lookahead macros (that used yystackp) are out of the way,
there is no reason to continue using a pointer.
* data/skeletons/glr2.cc: Use yystack, a reference, rather that
yystackp, a pointer.
Fix tons of const-correctness issues.
Now that we no longer play dangerous games with macros, we can give
the lookahead's token kind its proper name. The content of yychar
_is_ raw (as opposed to yytoken), there's no reason to pleonasmicate
it (and thus to neologize).
* data/skeletons/glr2.cc (glr_stack::yyrawchar): Rename as...
(glr_stack::yychar): this.
In glr.c, the macros yychar, yylval and yylloc allow to deal with
api.pure: sometimes they point to global variables (impure), sometimes
they point to the member variables (pure).
There's no room for globals in glr2.cc. Besides, they map yychar to
yyrawchar, yylval to yyval, etc. which obfuscates what is actually
going on.
* data/skeletons/glr2.cc (glr_stack::yyval, glr_stack::yyloc): Rename
as...
(glr_stack::yylval, glr_stack::yylloc): these, for clarity.
(yynerrs, yychar, yylval, yylloc, yystackp): Remove these macros.
(b4_yygetToken_call): Remove.
Restore a more natural order: first define the macros and then use
them. Currently, some macros were defined between the moment the
header is issued, and then the implementation file. As a result, it
was possible for the header and the implementation to not use the same
versions of the macros.
* data/skeletons/glr2.cc: Define the macros first, then use them.
* data/skeletons/lalr1.cc: Minor comment and quoting changes.
* data/skeletons/glr2.cc: Define value_type and location_type where
needed, and use them only.
(yyuserMerge): Make it a member function of the glr_state class.
We always refer to the triplet "kind, value, location". All of them
are nouns, and we support api.value.type and api.location.type. On
this regard, "semantic_type" was a poor choice. Make it "value_type".
The test suite was not updated to use value_type, on purpose, to
enforce backward compatibility.
* data/skeletons/c++.m4, data/skeletons/glr.cc, data/skeletons/glr2.cc,
* data/skeletons/variant.hh, doc/bison.texi: Define value_type rather
than semantic_type.
Add a backward compatibility typedef.
* examples/c++/glr/c++-types.yy: Migrate.
* data/skeletons/glr2.cc (glr_state_set::yyremoveDeletes): Use
vector::resize rather than vector::erase.
(glr_state::copyFrom): Merge into...
(glr_state::operator=): here.
Valentin wanted each assignment to be explicit, hence copyFrom rather
that operator=. But in 0a82316e54
(glr2.cc: example: use objects (not pointers) to represent the AST),
in order to get real objects to be processed correctly, we had to
introduce the assignment operator. Afterward, we also introduced a
full implementation of the copy-ctor, independent of copyFrom. As a
result, today the only invocation of copyFrom is from the assignment
operator. Simplify this.
With GCC10, the CI shows tons of warnings such as
(327. actions.at:374: testing Initial location: glr2.cc):
input.cc: In member function 'YYRESULTTAG glr_stack::yyglrReduce(state_set_index, rule_num, bool)':
input.cc:1357:11: error: '<anonymous>.glr_state::yyloc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
1357 | yyloc = other.yyloc;
| ~~~~~~^~~~~~~~~~~~~
This is because we don't have the constructors for locations. But we
should have them! That's only because of glr.cc that ctors were not
enabled by default. In glr2.cc, they should.
That fixes all the warnings when Bison's locations are used. However,
when user-defined locations without constructor are used, we still
have:
550. calc.at:1409: testing Calculator glr2.cc %locations api.location.type={Span} ...
calc.cc: In member function 'YYRESULTTAG glr_stack::yyglrReduce(state_set_index, rule_num, bool)':
calc.cc:1261:11: error: '<anonymous>.glr_state::yyloc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
1261 | yyloc = other.yyloc;
| ~~~~~~^~~~~~~~~~~~~
To address this case, we need glr_state to explicily initialize its
yyloc member.
* data/skeletons/glr2.cc: Use genuine objects, with ctors, for position
and location.
(glr_state): Explicitly initialize yyloc in the constructors.
The copy constructor was (lazily) implemented by a call to copyFrom.
Unfortunately copyFrom reads yyresolved from the destination (and
source), and in the case of the copy-ctor this is random garbagge,
which UBSAN catches:
glr-regr2a.cc:1072:10: runtime error: load of value 7, which is not a valid value for type 'bool'
Rather than defining yyresolved before calling copyFrom, let's just
provide a genuine cpy-ctor for glr_state.
* data/skeletons/glr2.cc (glr_state::glr_state): Implement properly.
In yycompressStack:
while (yyr != YY_NULLPTR)
{
nextFreeItem->check_ ();
yyr->check_();
nextFreeItem->setState(*yyr);
glr_state& nextFreeState = nextFreeItem->getState();
yyr = yyr->pred();
nextFreeState.setPred(&(nextFreeItem - 1)->getState());
setFirstTop(&nextFreeState);
++nextFreeItem;
}
it is possible that nextFreeItem and yyr are actually the same state.
In which case `nextFreeItem->setState(*yyr)` does really bad things.
* data/skeletons/glr2.cc (glr_stack_item::setState): Beware of
self-assignment.
* data/skeletons/glr.c: A bit more doc.
(yypstates): Rename yyst (only occurrence) to yys (commonly used for
yyGLRState).
* data/skeletons/glr2.cc: Ditto.
Prefer '\n' to "\n".
The complete symbol approach in yylex removes the need for the methods
semanticVal, startPos and endPos, which were used when the values were
reported separately.
* data/skeletons/lalr1.d: Here.
* doc/bison.texi: Remove sections about the three methods.
* examples/d/calc/calc.y, examples/d/simple/calc.y: Remove the unused methods.
* tests/calc.at, tests/d.at, tests/scanner.at: Test it.
* data/skeletons/d.m4 (b4_public_types_declare): Here.
* data/skeletons/lalr1.d: Adjust.
* doc/bison.texi: Document it.
* examples/d/calc/calc.y: Use it.
* tests/calc.at: Test it.
The yychar variable was keeping the external form of the token (the
TokenKind). As the D parser translates the token to its internal
form (the SymbolKind) inside the struct Symbol, there is no need for
yychar anymore.
* data/examples/lalr1.d (yychar): Remove.
Use only yytoken.
examples/c++/glr/c++-types.cc:721:24: error:
expected the class name after '~' to name a destructor
yysval.YYSTYPE::~semantic_type ();
^
Using a local typedef, for some reaon, result in clang complaining
about a useless local typedef. Since anyway we don't want to keep on
using YYSTYPE and YYLTYPE, it is time to introduce proper typedefs to
reach these guys. And to be slightly in advance of the other
skeletons: use value_type, not semantic_type. This is much more
consistent with our use of the (kind, value, location) triplet.
* data/skeletons/glr2.cc (glr_state::value_type)
(glr_state::location_type): New.
(glr_state::~glr_state): Use value_type to name the dtor.
Currently we are using pointers. The whole point of
glr2.cc (vs. glr.cc) is precisely to allow genuine C++ objects to be
semantic values. Let's make that work.
* data/skeletons/glr2.cc (glr_state::glr_state): Be sure to initialize
yysval.
(glr_state): Add copy-ctor, assignment and dtor.
(glr_state::copyFrom): Be sure to initialize the destination if it was
not.
(glr_state::~glr_state): Destroy the semantic value.
* examples/c++/glr/ast.hh: Rewrite so that we use genuine objects,
rather than a traditional OOP hierarchy that requires to deal with
pointers.
With help from Bruno Belanyi <bruno.belanyi@epita.fr>.
* examples/c++/glr/c++-types.yy: Remove memory management.
Use true objects.
(main): Don't reach yydebug directly.
* examples/c++/glr/local.mk: We need C++11.
When expanding the GLR stack, none of the pointers were updated to
reflect the new location of the displaced objects.
This fixes
748: Incorrect lookahead during nondeterministic GLR: glr2.cc
* data/skeletons/glr2.cc (yyexpandGLRStack): Update the split point
and the stack tops.
(reduceToOneStack): Factor a bit.
This test fails:
748: Incorrect lookahead during nondeterministic GLR: glr2.cc
It consumes lots of stack space, so at some point we need to expand
it. Because of Boolean logic mistakes, we then claim
memory-exhausted (first error). Hence we jump to cleaning the
stack (popall_), calling all the destructors, and at some point we
crash with heap-use-after-free (second error).
This commit fixes the first error. Unfortunately, even though we now
do expand the stack, we crash again with (another)
heap-use-after-free, not addressed here.
Eventually, we should make sure popall_() properly works.
* data/skeletons/glr2.cc (yyexpandGLRStackIfNeeded): Return true iff
success (i.e., memory not exhausted).
And also, remove the incorrect indentation of these comments:
- /* YYR2[YYN] -- Number of symbols on the right hand side of rule YYN. */
+/* YYR2[RULE-NUM] -- Number of symbols on the right-hand side of rule RULE-NUM. */
static const yytype_int8 yyr2[] =
{
0, 2, 4, 0, 2, 1, 1, 1, 3, 2,
I don't remember why this indentation was added (in
0991e29b75), but it seems wrong,
at least for yacc.c. I suspect this was done with lalr1.cc (where
this is embeded in the class definition, so it should be indented),
but today lalr1.cc uses other routines to output these comments.
* data/skeletons/bison.m4 (b4_integral_parser_tables_map): Improve the
wording of the comments of some tables.
* data/skeletons/c.m4 (b4_integral_parser_table_define): Remove
indentation.
A glr_stack_item has "raw" memory to store either a glr_state or a
semantic_option. glr_stack_item::setState stores a state using a copy
assignment. However, this is more like a construction: we are
starting from "raw" memory, so use the placement new operator instead.
While it probably makes no difference when parse.assert is disabled,
it does make one when it is: the constructor properly initialize the
magic number, the assignment does not. So without these changes, the
next commit (which stores genuine objects in semantic values) fails
tests 712 and 730 because of incorrect magic numbers.
* data/skeletons/glr2.cc (glr_stack_item::setState): Build the state,
don't just copy it.
Amusingly enough, glr2.cc still had its core function, yyparse, being
a free function instead of a member function.
* data/skeletons/glr2.cc (yyparse): Remove this free function called
from yyparser::parse. Inline its body into...
(yyparser::parse): this member function.
This requires moving a bit the yychar, etc. macros.
Access to token can be simplified (the
b4_namespace_ref::b4_parser_class prefix is no longer needed).
