> On 03 June 2022 at 19:37 Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> wrote: > > > Add an ASSERT_FOR_FANALYZER() macro to quiet those -fanalyzer issues If the purpose of the macro is to silence -fanalyzer then it would perhaps be better to name it after that purpose rather than the way that it is implemented. SILENCE_FANALYZER_WARNING() or something like that. > that haven't been diagnosed yet to either change the code involved, or > to add an assert() or BUG() to it to placate GCC v12's -fanalyzer > mode. > > As in the preceding commit we could also use -Wno-error=* here, which > was the initial implementation in config.mak.dev, i.e. something like: > > ## -Wno-error=analyzer-null-dereference > $(eval $(call fn_disable_analyzer, \ > -Wno-error=analyzer-null-dereference, \ > dir \ > gpg-interface \ > graph \ > range-diff \ > utf8 \ > )) > ## -Wno-error=analyzer-null-dereference: pre-gcc12 > ifeq ($(filter gcc12,$(COMPILER_FEATURES)),) > $(eval $(call fn_disable_analyzer, \ > -Wno-error=analyzer-null-dereference, \ > merge \ > builtin/name-rev \ > )) > endif > > But any such approach will unfortunately quiet *all* in the relevant > files, including any new ones. Instead we want to quiet specific > issues involved with ASSERT_FOR_FANALYZER(). I had a hard time understanding this, maybe But any such approach will unfortunately miss any new warnings as it silences them for the whole file. Best Wishes Phillip > > A drawback of this overall approach is that this only works under > e.g. CFLAGS=-O0, but not CFLAGS=-O3. The compiler takes the liberty to > re-arrange our code to get around these assert()s, and other new > issues will also crop up. All of this is expected (-fanalyzer is > subject to optimization passes, like most other options), but let's > focus on -O0 for now. > > Commentary on specific cases: > > * builtin/name-rev.c: Since 45a14f578e1 (Revert "name-rev: release > unused name strings", 2022-04-22) GCC v12's -fanalyzer has complained > about this code, per René's analysis in [1] it's incorrect to do > so. So let's add an ASSERT_FOR_FANALYZER() to placate it. > > * graph.c: In 0f0f389f120 (graph: tidy up display of left-skewed > merges, 2019-10-15) a previous "assert" was removed, and another > unconditional deference of the return value of > first_interesting_parent() was added without checking it. Since it > can return NULL let's add ASSERT_FOR_FANALYZER()'s here to note for > -fanalyzer that we won't be dereferencing these in practice. > > 1. https://lore.kernel.org/git/dece627d-ccf8-2375-0c50-c59637e561d3@xxxxxx/ > > Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> > --- > builtin/name-rev.c | 1 + > config.mak.dev | 4 ++++ > dir.c | 1 + > git-compat-util.h | 16 ++++++++++++++++ > gpg-interface.c | 2 ++ > graph.c | 2 ++ > line-log.c | 2 ++ > unpack-trees.c | 1 + > utf8.c | 1 + > 9 files changed, 30 insertions(+) > > diff --git a/builtin/name-rev.c b/builtin/name-rev.c > index 02ea9d16330..419159961b9 100644 > --- a/builtin/name-rev.c > +++ b/builtin/name-rev.c > @@ -223,6 +223,7 @@ static void name_rev(struct commit *start_commit, > if (commit_is_before_cutoff(parent)) > continue; > > + ASSERT_FOR_FANALYZER(name); > if (parent_number > 1) { > generation = 0; > distance = name->distance + MERGE_TRAVERSAL_WEIGHT; > diff --git a/config.mak.dev b/config.mak.dev > index d6f5be92297..1d47fc04163 100644 > --- a/config.mak.dev > +++ b/config.mak.dev > @@ -83,6 +83,10 @@ endif > > DEVELOPER_CFLAGS += -fanalyzer > > +ifeq ($(filter no-suppress-analyzer,$(DEVOPTS)),) > +DEVELOPER_CFLAGS += -DSUPPRESS_FSANITIZER > +endif > + > ## -fanalyzer exists exists as of gcc10, but versions older than gcc12 > ## have a lot of false positives. > ifeq ($(filter gcc12,$(COMPILER_FEATURES)),) > diff --git a/dir.c b/dir.c > index 3633c0852ee..c80b584b4a7 100644 > --- a/dir.c > +++ b/dir.c > @@ -3781,6 +3781,7 @@ static void invalidate_one_directory(struct untracked_cache *uc, > struct untracked_cache_dir *ucd) > { > uc->dir_invalidated++; > + ASSERT_FOR_FANALYZER(ucd); > ucd->valid = 0; > ucd->untracked_nr = 0; > } > diff --git a/git-compat-util.h b/git-compat-util.h > index 96293b6c43a..a553884c048 100644 > --- a/git-compat-util.h > +++ b/git-compat-util.h > @@ -984,6 +984,21 @@ static inline unsigned long cast_size_t_to_ulong(size_t a) > return (unsigned long)a; > } > > +/** > + * Transitory helper macro to quiet currently known GCC -fsanitizer > + * issues. > + * > + * We lie to it and say that we're confident that the given "expr" to > + * ASSERT_FOR_FANALYZER() cannot be NULL (or 0). Those > + * grandfathered-in issues should be fixed, but at least we're > + * stemming the tide. > + */ > +#ifdef SUPPRESS_FSANITIZER > +#define ASSERT_FOR_FANALYZER(expr) assert((expr)) > +#else > +#define ASSERT_FOR_FANALYZER(expr) do {} while (0) > +#endif > + > #ifdef HAVE_ALLOCA_H > # include <alloca.h> > # define xalloca(size) (alloca(size)) > @@ -1037,6 +1052,7 @@ int xstrncmpz(const char *s, const char *t, size_t len); > BUILD_ASSERT_OR_ZERO(sizeof(*(dst)) == sizeof(*(src)))) > static inline void copy_array(void *dst, const void *src, size_t n, size_t size) > { > + ASSERT_FOR_FANALYZER(dst); > if (n) > memcpy(dst, src, st_mult(size, n)); > } > diff --git a/gpg-interface.c b/gpg-interface.c > index 280f1fa1a58..9cba3b86e45 100644 > --- a/gpg-interface.c > +++ b/gpg-interface.c > @@ -242,6 +242,7 @@ static void parse_gpg_output(struct signature_check *sigc) > next = strchrnul(line, ' '); > replace_cstring(&sigc->key, line, next); > /* Do we have signer information? */ > + ASSERT_FOR_FANALYZER(next); > if (*next && (sigcheck_gpg_status[i].flags & GPG_STATUS_UID)) { > line = next + 1; > next = strchrnul(line, '\n'); > @@ -283,6 +284,7 @@ static void parse_gpg_output(struct signature_check *sigc) > */ > limit = strchrnul(line, '\n'); > for (j = 9; j > 0; j--) { > + ASSERT_FOR_FANALYZER(next); > if (!*next || limit <= next) > break; > line = next + 1; > diff --git a/graph.c b/graph.c > index 568b6e7cd41..39f7e95d4ab 100644 > --- a/graph.c > +++ b/graph.c > @@ -1105,6 +1105,7 @@ static void graph_output_post_merge_line(struct git_graph *graph, struct graph_l > seen_this = 1; > > for (j = 0; j < graph->num_parents; j++) { > + ASSERT_FOR_FANALYZER(parents); > par_column = graph_find_new_column_by_commit(graph, parents->item); > assert(par_column >= 0); > > @@ -1138,6 +1139,7 @@ static void graph_output_post_merge_line(struct git_graph *graph, struct graph_l > } > } > > + ASSERT_FOR_FANALYZER(first_parent); > if (col_commit == first_parent->item) > parent_col = col; > } > diff --git a/line-log.c b/line-log.c > index 51d93310a4d..1295f46deaf 100644 > --- a/line-log.c > +++ b/line-log.c > @@ -154,6 +154,7 @@ static void range_set_union(struct range_set *out, > while (i < a->nr || j < b->nr) { > struct range *new_range; > if (i < a->nr && j < b->nr) { > + ASSERT_FOR_FANALYZER(rb); > if (ra[i].start < rb[j].start) > new_range = &ra[i++]; > else if (ra[i].start > rb[j].start) > @@ -166,6 +167,7 @@ static void range_set_union(struct range_set *out, > new_range = &ra[i++]; > else /* a exhausted */ > new_range = &rb[j++]; > + ASSERT_FOR_FANALYZER(new_range); > if (new_range->start == new_range->end) > ; /* empty range */ > else if (!out->nr || out->ranges[out->nr-1].end < new_range->start) { > diff --git a/unpack-trees.c b/unpack-trees.c > index a1d0ff3a4d3..b6e10b05a00 100644 > --- a/unpack-trees.c > +++ b/unpack-trees.c > @@ -2195,6 +2195,7 @@ static int verify_clean_subdirectory(const struct cache_entry *ce, > char *pathbuf; > int cnt = 0; > > + ASSERT_FOR_FANALYZER(ce); > if (S_ISGITLINK(ce->ce_mode)) { > struct object_id oid; > int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid); > diff --git a/utf8.c b/utf8.c > index de4ce5c0e68..3ffc0a97f3b 100644 > --- a/utf8.c > +++ b/utf8.c > @@ -130,6 +130,7 @@ static ucs_char_t pick_one_utf8_char(const char **start, size_t *remainder_p) > */ > remainder = (remainder_p ? *remainder_p : 999); > > + ASSERT_FOR_FANALYZER(remainder < 1 || s); > if (remainder < 1) { > goto invalid; > } else if (*s < 0x80) { > -- > 2.36.1.1124.g577fa9c2ebd >
