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[PATCH 1/4] glr2.cc: disable incorrect warnings from GCC6 to 9
From: |
Akim Demaille |
Subject: |
[PATCH 1/4] glr2.cc: disable incorrect warnings from GCC6 to 9 |
Date: |
Sun, 13 Sep 2020 14:42:36 +0200 |
For instance with GCC8:
616. regression.at:1560: testing Lex and parse params: glr2.cc ...
tests/regression.at:1560: COLUMNS=1000; export COLUMNS;
NO_TERM_HYPERLINKS=1; export NO_TERM_HYPERLINKS; bison --color=no -fno-caret
-o input.cc input.y
tests/regression.at:1560: $CXX $CXXFLAGS $CPPFLAGS $LDFLAGS -o input
input.cc $LIBS
stderr:
input.cc: In member function 'YYRESULTTAG
glr_stack::yyresolveValue(glr_state*)':
input.cc:1796:10: error: potential null pointer dereference
[-Werror=null-dereference]
return yypred ? &(asItem(this) - yypred)->getState() : YY_NULLPTR;
^~~~~~
input.cc:1796:10: error: potential null pointer dereference
[-Werror=null-dereference]
return yypred ? &(asItem(this) - yypred)->getState() : YY_NULLPTR;
^~~~~~
cc1plus: all warnings being treated as errors
It complains that the implicit this in yypred might be null. It fears
it because of loops such as
for (glr_state* yys = firstTopState();
yys != yystateStack.yysplitPoint;
yys = yys->pred())
yyn += 1;
that could possibly set yys to null, since yys->pred might return
null. However, the warning is incorrect, since in C++ `this` cannot
be null. GCC 10 no longer emits this warning.
GCC 7 also complains many times about glr_stack::yyresolveLocations
when NDEBUG is enabled (when it is not, YYASSERT (yyoption !=
YY_NULLPTR) is probably enough to pacify GCC):
616. regression.at:1560: testing Lex and parse params: glr2.cc ...
tests/regression.at:1560: COLUMNS=1000; export COLUMNS;
NO_TERM_HYPERLINKS=1; export NO_TERM_HYPERLINKS; bison --color=no -fno-caret
-o input.cc input.y
tests/regression.at:1560: $CXX $CXXFLAGS $CPPFLAGS $LDFLAGS -o input
input.cc $LIBS
stderr:
input.cc: In member function 'void
glr_stack::yyresolveLocations(glr_state*, int)':
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc: In member function 'YYRESULTTAG
glr_stack::yyresolveValue(glr_state*)':
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
input.cc:3061:46: error: potential null pointer dereference
[-Werror=null-dereference]
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
* data/skeletons/glr2.cc (YY_IGNORE_NULL_DEREFERENCE_BEGIN)
(YY_IGNORE_NULL_DEREFERENCE_BEGIN): New.
(glr_state::pred, glr_stack::yyresolveLocations): Use them.
---
TODO | 13 ++++++++++---
data/skeletons/glr2.cc | 27 +++++++++++++++++++++++----
2 files changed, 33 insertions(+), 7 deletions(-)
diff --git a/TODO b/TODO
index 3f4d1978..c692b9f9 100644
--- a/TODO
+++ b/TODO
@@ -158,9 +158,12 @@ Les catégories d'avertissements incluent :
Line -1 and -3 should mention CATEGORIE, not CATEGORY.
* Bison 3.8
-** Rewrite glr.cc
-*** glr.c
-Get rid of scaffolding in glr.c.
+** Rewrite glr.cc (currently glr2.cc)
+*** Remove jumps
+We can probably replace setjmp/longjmp with exceptions. That would help
+tremendously other languages such as D and Java that probably have no
+similar feature. If we remove jumps, we probably no longer need _Noreturn,
+so simplify `b4_attribute_define([noreturn])` into `b4_attribute_define`.
*** Coding style
Move to our coding conventions. In particular names such as yy_glr_stack,
@@ -178,6 +181,10 @@ There are many places where pointers should be replaced
with references.
Don't use YYSTYPE and YYLTYPE but parser::semantic_type and
parser::location_type. Undefine YYSTYPE and YYLTYPE.
+*** glr.c
+When glr2.cc fully replaces glr.cc, get rid of the glr.cc scaffolding in
+glr.c.
+
* Chains
** Unit rules / Injection rules (Akim Demaille)
Maybe we could expand unit rules (or "injections", see
diff --git a/data/skeletons/glr2.cc b/data/skeletons/glr2.cc
index a7f2d129..e463ffb3 100644
--- a/data/skeletons/glr2.cc
+++ b/data/skeletons/glr2.cc
@@ -126,6 +126,17 @@ b4_percent_code_get([[requires]])[
]b4_cast_define[
]b4_null_define[
+#if defined __GNUC__ && ! defined __ICC && 6 <= __GNUC__ && __GNUC__ <= 9
+# define YY_IGNORE_NULL_DEREFERENCE_BEGIN \
+ _Pragma ("GCC diagnostic push") \
+ _Pragma ("GCC diagnostic ignored \"-Wnull-dereference\"")
+# define YY_IGNORE_NULL_DEREFERENCE_END \
+ _Pragma ("GCC diagnostic pop")
+#else
+# define YY_IGNORE_NULL_DEREFERENCE_BEGIN
+# define YY_IGNORE_NULL_DEREFERENCE_END
+#endif
+
// Whether we are compiled with exception support.
#ifndef YY_EXCEPTIONS
# if defined __GNUC__ && !defined __EXCEPTIONS
@@ -1271,12 +1282,18 @@ public:
bool is_state_;
};
-glr_state* glr_state::pred() {
- return yypred ? &(asItem(this) - yypred)->getState() : YY_NULLPTR;
+glr_state* glr_state::pred ()
+{
+ YY_IGNORE_NULL_DEREFERENCE_BEGIN
+ return yypred ? &(asItem (this) - yypred)->getState () : YY_NULLPTR;
+ YY_IGNORE_NULL_DEREFERENCE_END
}
-const glr_state* glr_state::pred() const {
- return yypred ? &(asItem(this) - yypred)->getState() : YY_NULLPTR;
+const glr_state* glr_state::pred () const
+{
+ YY_IGNORE_NULL_DEREFERENCE_BEGIN
+ return yypred ? &(asItem (this) - yypred)->getState () : YY_NULLPTR;
+ YY_IGNORE_NULL_DEREFERENCE_END
}
void glr_state::setPred(const glr_state* state) {
@@ -2606,7 +2623,9 @@ class glr_stack {
detected. Thus the location of the previous state (but not
necessarily the previous state itself) is guaranteed to be
resolved already. */
+ YY_IGNORE_NULL_DEREFERENCE_BEGIN
yyrhsloc[0].getState().yyloc = yyoption->state()->yyloc;
+ YY_IGNORE_NULL_DEREFERENCE_END
}
YYLLOC_DEFAULT ((yys1->yyloc), yyrhsloc, yynrhs);
}
--
2.28.0