[gcc r11-5115] Daily bump.

[gcc r11-5115] Daily bump.

[GCC Administrator]

https://gcc.gnu.org/g:4dabb03719553f88ef0d74c75ccdc6c8aa172d6b

commit r11-5115-g4dabb03719553f88ef0d74c75ccdc6c8aa172d6b
Author: GCC Administrator <gccadmin@gcc.gnu.org>
Date:   Wed Nov 18 00:16:34 2020 +0000

    Daily bump.

Diff:
---
 gcc/ChangeLog           | 178 ++++++++++++++++++++++++++++++++++++++++++++++++
 gcc/DATESTAMP           |   2 +-
 gcc/c-family/ChangeLog  |  41 +++++++++++
 gcc/cp/ChangeLog        |  16 +++++
 gcc/fortran/ChangeLog   |   5 ++
 gcc/lto/ChangeLog       |   7 ++
 gcc/testsuite/ChangeLog | 135 ++++++++++++++++++++++++++++++++++++
 libcpp/ChangeLog        |  29 ++++++++
 libstdc++-v3/ChangeLog  |  27 ++++++++
 9 files changed, 439 insertions(+), 1 deletion(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1adcbd8a8c7..2e7d91bcab0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,181 @@
+2020-11-17  Sebastian Pop  <spop@amazon.com>
+
+	* config.gcc: add configure flags --with-{cpu,arch,tune}-{32,64}
+	as alias flags for --with-{cpu,arch,tune} on AArch64.
+	* doc/install.texi: Document new flags for aarch64.
+
+2020-11-17  Sebastian Pop  <spop@amazon.com>
+
+	* config.gcc: Add --with-tune to AArch64 configure flags.
+
+2020-11-17  Andrew MacLeod  <amacleod@redhat.com>
+
+	PR tree-optimization/91029
+	* range-op.cc (operator_trunc_mod::op1_range): New.
+
+2020-11-17  Jan Hubicka  <jh@suse.cz>
+
+	* ipa-icf.c (sem_function::hash_stmt): Fix conditional on
+	variably_modified_type_p.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* tree.h (cache_integer_cst): Add defaulted might_duplicate parm.
+	* tree.c (cache_integer_cst): Return the integer cst, add
+	might_duplicate parm to permit finding a small duplicate.
+
+2020-11-17  Andrew MacLeod  <amacleod@redhat.com>
+
+	PR tree-optimization/83072
+	* range-op.cc (wi_optimize_and_or): Remove zero from IOR range when
+	mask is non-zero.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* ginclude/float.h (CR_DECIMAL_DIG): Also define for
+	[__STDC_WANT_IEC_60559_EXT__].
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* ginclude/float.h [__STDC_VERSION__ > 201710L] (FLT_IS_IEC_60559,
+	DBL_IS_IEC_60559, LDBL_IS_IEC_60559): New macros.
+
+2020-11-17  Aaron Sawdey  <acsawdey@linux.ibm.com>
+
+	PR target/96791
+	* mode-classes.def: Add MODE_OPAQUE.
+	* machmode.def: Add OPAQUE_MODE.
+	* tree.def: Add OPAQUE_TYPE for types that will use
+	MODE_OPAQUE.
+	* doc/generic.texi: Document OPAQUE_TYPE.
+	* doc/rtl.texi: Document MODE_OPAQUE.
+	* machmode.h: Add OPAQUE_MODE_P().
+	* genmodes.c (complete_mode): Add MODE_OPAQUE.
+	(opaque_mode): New function.
+	* tree.c (tree_code_size): Add OPAQUE_TYPE.
+	* tree.h: Add OPAQUE_TYPE_P().
+	* stor-layout.c (int_mode_for_mode): Treat MODE_OPAQUE modes
+	like BLKmode.
+	* ira.c (find_moveable_pseudos): Treat MODE_OPAQUE modes more
+	like integer/float modes here.
+	* dbxout.c (dbxout_type): Treat OPAQUE_TYPE like VOID_TYPE.
+	* tree-pretty-print.c (dump_generic_node): Treat OPAQUE_TYPE
+	like like other types.
+
+2020-11-17  Jan Hubicka  <hubicka@ucw.cz>
+	    Martin Liska  <mliska@suse.cz>
+
+	* ipa-icf.c: Include data-streamer.h and alias.h.
+	(sem_function::sem_function): Initialize memory_access_types
+	and m_alias_sets_hash.
+	(sem_function::hash_stmt): For memory accesses and when going to
+	do lto streaming add base and ref types into memory_access_types.
+	(sem_item_optimizer::write_summary): Stream memory access types.
+	(sem_item_optimizer::read_section): Likewise and also iniitalize
+	m_alias_sets_hash.
+	(sem_item_optimizer::execute): Call
+	sem_item_optimizer::update_hash_by_memory_access_type.
+	(sem_item_optimizer::update_hash_by_memory_access_type): Updat.
+	* ipa-icf.h (sem_function): Add memory_access_types and
+	m_alias_sets_hash.
+
+2020-11-17  Jan Hubicka  <jh@suse.cz>
+
+	PR bootstrap/97857
+	* ipa-devirt.c (odr_based_tbaa_p): Do not ICE when
+	odr_hash is not initialized
+	* ipa-utils.h (type_with_linkage_p): Do not sanity check
+	CXX_ODR_P.
+	* tree-streamer-out.c (pack_ts_type_common_value_fields): Set
+	CXX_ODR_P according to the canonical type.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* langhooks-def.h (LANG_HOOKS_PREPROCESS_MAIN_FILE)
+	(LANG_HOOKS_PREPROCESS_OPTIONS, LANG_HOOKS_PREPROCESS_UNDEF)
+	(LANG_HOOKS_PREPROCESS_TOKEN): New.
+	(LANG_HOOKS_INITIALIZER): Add them.
+	* langhooks.h (struct lang_hooks): Add preprocess_main_file,
+	preprocess_options, preprocess_undef, preprocess_token hooks.  Add
+	enum PT_flags.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR tree-optimization/97693
+	* tree-vect-stmts.c (vectorizable_call): Pass the required vectype
+	to vect_get_vec_defs_for_operand.
+
+2020-11-17  Liu Hao  <lh_mouse@126.com>
+
+	* config/i386/msformat-c.c: Add more length modifiers.
+
+2020-11-17  Tamar Christina  <tamar.christina@arm.com>
+
+	PR driver/97574
+	* gcc.c (convert_filename): Don't add suffix to things that are
+	not files.
+	(not_actual_file_p): Use supplied argument.
+
+2020-11-17  Haochen Gui  <guihaoc@gcc.gnu.org>
+
+	* final.c (final_scan_insn_1): Set jump table relocatable as the
+	second argument of targetm.asm_out.function_rodata_section.
+	* output.h (default_function_rodata_section,
+	default_no_function_rodata_section): Add the second argument to the
+	declarations.
+	* target.def (function_rodata_section): Change the doc and add
+	the second argument.
+	* doc/tm.texi: Regenerate.
+	* varasm.c (jumptable_relocatable): Implement.
+	(default_function_rodata_section): Add the second argument
+	and the support for relocatable read only sections.
+	(default_no_function_rodata_section): Add the second argument.
+	(function_mergeable_rodata_prefix): Set the second argument to false.
+	* config/mips/mips.c (mips_function_rodata_section): Add the second
+	arugment and set it to false.
+	* config/s390/s390.c (targetm.asm_out.function_rodata_section): Set
+	the second argument to false.
+	* config/s390/s390.md: Likewise.
+
+2020-11-17  liuhongt  <hongtao.liu@intel.com>
+
+	PR target/97194
+	* config/i386/i386-expand.c (ix86_expand_vector_set_var): New function.
+	* config/i386/i386-protos.h (ix86_expand_vector_set_var): New Decl.
+	* config/i386/predicates.md (vec_setm_operand): New predicate,
+	true for const_int_operand or register_operand under TARGET_AVX2.
+	* config/i386/sse.md (vec_set<mode>): Support both constant
+	and variable index vec_set.
+
+2020-11-17  Martin Sebor  <msebor@redhat.com>
+
+	* tree-ssa-uninit.c (maybe_warn_operand): Call is_empty_type.
+	* tree.c (default_is_empty_type): Rename...
+	(is_empty_type): ...to this.
+	* tree.h (is_empty_type): Declare.
+
+2020-11-17  Martin Sebor  <msebor@redhat.com>
+
+	PR middle-end/95673
+	* tree-ssa-strlen.c (used_only_for_zero_equality): Rename...
+	(use_in_zero_equality): ...to this.  Add a default argument.
+	(handle_builtin_memcmp): Adjust to the name change above.
+	(handle_builtin_string_cmp): Same.
+	(maybe_warn_pointless_strcmp): Same.  Pass in an explicit argument.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* ginclude/float.h (DEC32_SNAN, DEC64_SNAN, DEC128_SNAN): New C2x
+	macros.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* ginclude/float.h (INFINITY, NAN, FLT_SNAN, DBL_SNAN, LDBL_SNAN)
+	(FLT16_SNAN, FLT32_SNAN, FLT64_SNAN, FLT128_SNAN, FLT32X_SNAN)
+	(FLT64X_SNAN, FLT128X_SNAN, DEC_INFINITY, DEC_NAN): New C2x
+	macros.
+	* doc/sourcebuild.texi (Effective-Target Keywords): Document inff.
+
 2020-11-17  Armin Brauns via Gcc-patches  <gcc-patches@gcc.gnu.org>
 
 	* gcc.c: Document %T spec file directive.
diff --git a/gcc/DATESTAMP b/gcc/DATESTAMP
index 0ad54ab67bd..6ee7c2ae987 100644
--- a/gcc/DATESTAMP
+++ b/gcc/DATESTAMP
@@ -1 +1 @@
-20201117
+20201118
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index dc15a61ee06..3fec8f24ee9 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,44 @@
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* c-common.h (enum c_tree_index): Reorder to place lazy fields
+	after newly-added CTI_MODULE_HWM.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* c-cppbuiltin.c (builtin_define_float_constants): Define
+	"*_IS_IEC_60559__" macros.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* c-lex.c: #include "langhooks.h".
+	(cb_undef): Maybe call preprocess_undef lang hook.
+	* c-opts.c (c_common_post_options): Maybe call preprocess_options
+	lang hook.
+	(push_command_line_include): Maybe call preprocess_main_file lang
+	hook.
+	(cb_file_change): Likewise.
+	* c-ppoutput.c: #include "langhooks.h.
+	(scan_translation_unit): Maybe call preprocess_token lang hook.
+	(class do_streamer): New, derive from token_streamer.
+	(directives_only_cb): Data pointer is do_streamer, call
+	preprocess_token lang hook.
+	(scan_translation_unit_directives_only): Use do_streamer.
+	(print_line_1): Move src_line recording to after string output.
+	(cb_undef): Maybe call preprocess_undef lang hook.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* c-ppoutput.c (scan_translation_unit): Use token_streamer, remove
+	code duplicating that functionality.
+
+2020-11-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/90628
+	* c-common.c (check_builtin_function_arguments)
+	<case BUILT_IN_ADD_OVERFLOW>: Diagnose when last argument is pointer
+	to _Atomic.  For the TYPE_READONLY case, adjust message to be usable
+	for more builtins and argument positions.
+
 2020-11-16  Iain Sandoe  <iain@sandoe.co.uk>
 
 	PR objc/97854
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 83d788506f2..0f418629c93 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,19 @@
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	PR c++/97877
+	* decl.c (duplicate_decls): Deal with duplicated DECL_LOCAL_DECL_P
+	decls.  Extend decl_lang_specific checking assert.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* cp-tree.h (enum cp_tree_index): Reorder to place lazy fields
+	after newly-added CPTI_MODULE_HWM.
+
+2020-11-17  Iain Sandoe  <iain@sandoe.co.uk>
+
+	PR c++/97871
+	* parser.c (cp_parser_declaration): Remove checking assert.
+
 2020-11-15  Jason Merrill  <jason@redhat.com>
 
 	* decl.c (cp_finish_decl): Only check abstractness on definition.
diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 7bff1b2d5a3..69b337c64db 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,8 @@
+2020-11-17  Harald Anlauf  <anlauf@gmx.de>
+
+	* gfortran.texi: Fix description of GFC_RTCHECK_* to match actual
+	code.
+
 2020-11-16  Harald Anlauf  <anlauf@gmx.de>
 
 	* trans-intrinsic.c (gfc_conv_intrinsic_size): Generate runtime
diff --git a/gcc/lto/ChangeLog b/gcc/lto/ChangeLog
index d33607422ea..29d07052ac0 100644
--- a/gcc/lto/ChangeLog
+++ b/gcc/lto/ChangeLog
@@ -1,3 +1,10 @@
+2020-11-17  Jan Hubicka  <jh@suse.cz>
+
+	PR bootstrap/97857
+	* lto-common.c (gimple_register_canonical_type_1): Only
+	register types with TYPE_CXX_ODR_P flag; sanity check that no
+	conflict happens at ltrans time.
+
 2020-11-06  Nathan Sidwell  <nathan@acm.org>
 
 	* lto-symtab.c (lto_symtab_merge_decls_1): Rename
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8672fd885ca..ec4c0d74055 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,138 @@
+2020-11-17  Andrew MacLeod  <amacleod@redhat.com>
+
+	* gcc.dg/pr91029.c: New.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	PR c++/97877
+	* g++.dg/lookup/pr97877.C: New.
+
+2020-11-17  Andrew MacLeod  <amacleod@redhat.com>
+
+	* gcc.dg/pr83072.c: New.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* gcc.dg/cr-decimal-dig-3.c: New test.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* gcc.dg/c11-float-6.c, gcc.dg/c2x-float-10.c: New tests.
+
+2020-11-17  David Edelsohn  <dje.gcc@gmail.com>
+
+	* gcc.dg/pr25376.c: Allow .opd section.
+
+2020-11-17  H.J. Lu  <hjl.tools@gmail.com>
+
+	PR target/31799
+	* gcc.target/i386/pr31799.c: New test.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.target/aarch64/sve/cond_cnot_1.c: Remove XFAIL.
+	* gcc.target/aarch64/sve/cond_unary_1.c: Likewise.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR tree-optimization/97693
+	* gcc.dg/vect/pr97693.c: New test.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/slp-46.c: XFAIL test for SLP on vect_load_lanes targets.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/aligned-section-anchors-nest-1.c: XFAIL alignment
+	test if vect_element_align_preferred.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/bb-slp-subgroups-3.c: XFAIL for variable-length vectors.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/pr65947-8.c: Expect the loop to be vectorized for SVE.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/pr97678.c: XFAIL test for SLP vectorization
+	for variable-length vectors.
+	* gcc.dg/vect/pr97835.c: Likewise.
+	* gcc.dg/vect/slp-49.c: Likewise.
+	* gcc.dg/vect/vect-outer-slp-1.c: Likewise.
+	* gcc.dg/vect/vect-outer-slp-2.c: Likewise.
+	* gcc.dg/vect/vect-outer-slp-3.c: Likewise.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/slp-reduc-4.c: XFAIL test for SLP vectorization
+	for variable-length SVE.
+	* gcc.dg/vect/slp-reduc-7.c: Likewise.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/bb-slp-43.c: Remove XFAIL for vect_variable_length.
+
+2020-11-17  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* gcc.dg/vect/pr91750.c: Allow "[]," inside a vector(...) lane count.
+
+2020-11-17  Liu Hao  <lh_mouse@126.com>
+
+	* gcc.dg/format/ms_c99-printf-3.c: Update tests.
+
+2020-11-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/90628
+	* gcc.dg/builtin-arith-overflow-4.c: New test.
+
+2020-11-17  Jakub Jelinek  <jakub@redhat.com>
+
+	* gcc.dg/guality/pr59776.c (foo): Use noipa attribute instead of
+	noinline, noclone.
+
+2020-11-17  liuhongt  <hongtao.liu@intel.com>
+
+	* gcc.target/i386/avx2-vec-set-1.c: New test.
+	* gcc.target/i386/avx2-vec-set-2.c: New test.
+	* gcc.target/i386/avx512bw-vec-set-1.c: New test.
+	* gcc.target/i386/avx512bw-vec-set-2.c: New test.
+	* gcc.target/i386/avx512f-vec-set-2.c: New test.
+	* gcc.target/i386/avx512vl-vec-set-2.c: New test.
+
+2020-11-17  Martin Sebor  <msebor@redhat.com>
+
+	PR middle-end/95673
+	* gcc.dg/Wstring-compare-3.c: New test.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* gcc.dg/dfp/c2x-float-dfp-7.c, gcc.dg/dfp/c2x-float-dfp-8.c: New
+	tests.
+	* gcc.dg/c2x-float-no-dfp-3.c: Also check that DEC32_SNAN,
+	DEC64_SNAN and DEC128_SNAN are not defined.
+
+2020-11-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* lib/target-supports.exp (check_effective_target_inff): New.
+	* gcc.dg/c11-float-4.c, gcc.dg/c11-float-5.c,
+	gcc.dg/c11-float-dfp-2.c, gcc.dg/c2x-float-2.c,
+	gcc.dg/c2x-float-3.c, gcc.dg/c2x-float-4.c, gcc.dg/c2x-float-5.c,
+	gcc.dg/c2x-float-6.c, gcc.dg/c2x-float-7.c, gcc.dg/c2x-float-8.c,
+	gcc.dg/c2x-float-9.c, gcc.dg/c2x-float-no-dfp-3.c,
+	gcc.dg/c2x-float-no-dfp-4.c, gcc.dg/dfp/c2x-float-dfp-4.c,
+	gcc.dg/dfp/c2x-float-dfp-5.c, gcc.dg/dfp/c2x-float-dfp-6.c,
+	gcc.dg/torture/float128-nan-floath.c,
+	gcc.dg/torture/float128x-nan-floath.c,
+	gcc.dg/torture/float16-nan-floath.c,
+	gcc.dg/torture/float32-nan-floath.c,
+	gcc.dg/torture/float32x-nan-floath.c,
+	gcc.dg/torture/float64-nan-floath.c,
+	gcc.dg/torture/float64x-nan-floath.c,
+	gcc.dg/torture/floatn-nan-floath.h: New tests.
+
 2020-11-16  Roger Sayle  <roger@nextmovesoftware.com>
 
 	PR rtl-optimization/92180
diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index e412bc22a87..2b3546b68b8 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,32 @@
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* include/cpplib.h (struct cpp_callbacks): Add
+	user_deferred_macro & translate_include.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	* include/line-map.h (enum lc_reason): Add LC_MODULE.
+	(MAP_MODULE_P): New.
+	(line_map_new_raw): Declare.
+	(linemap_enter_macro): Move declaration from internal.h
+	(linemap_module_loc, linemap_module_reparent)
+	(linemap_module_restore): Declare.
+	(linemap_lookup_macro_indec): Declare.
+	* internal.h (linemap_enter_macro): Moved to line-map.h.
+	* line-map.c (linemap_new_raw): New, broken out of ...
+	(new_linemap): ... here.  Call it.
+	(LAST_SOURCE_LINE_LOCATION): New.
+	(liemap_module_loc, linemap_module_reparent)
+	(linemap_module_restore): New.
+	(linemap_lookup_macro_index): New, broken out of ...
+	(linemap_macro_map_lookup): ... here.  Call it.
+	(linemap_dump): Add module dump.
+
+2020-11-17  Nathan Sidwell  <nathan@acm.org>
+
+	PR preprocessor/97858
+	* mkdeps.c (munge): Drop varadic args, we only ever use one.
+
 2020-11-13  Joseph Myers  <joseph@codesourcery.com>
 
 	* expr.c (cpp_classify_number): Update diagnostic for binary
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 43f6f3938f8..471069b8f91 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,30 @@
+2020-11-17  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/93421
+	* acinclude.m4 (GLIBCXX_ENABLE_LIBSTDCXX_TIME): Fail if struct
+	timespec isn't compatible with SYS_clock_gettime.
+	* configure: Regenerate.
+	* src/c++11/chrono.cc: Revert changes for time64 compatibility.
+	Add static_assert instead.
+	* src/c++11/futex.cc (_M_futex_wait_until_steady): Assume
+	SYS_clock_gettime can use struct timespec.
+
+2020-11-17  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/97869
+	* include/precompiled/stdc++.h: Include <coroutine>.
+	* include/std/version (__cpp_lib_span): Check __cpp_lib_concepts
+	before defining.
+
+2020-11-17  Patrick Palka  <ppalka@redhat.com>
+
+	PR libstdc++/97828
+	* include/bits/ranges_algo.h (__search_n_fn::operator()): Check
+	random_access_iterator before using the backtracking
+	implementation.  When the backwards scan fails prematurely,
+	reset __remainder appropriately.
+	* testsuite/25_algorithms/search_n/97828.cc: New test.
+
 2020-11-16  Jonathan Wakely  <jwakely@redhat.com>
 
 	* src/Makefile.am (libstdc++-symbols.ver-sun): Remove -lrt from