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Warning about trigraph on generated assembly code #6373

vicuna opened this issue Apr 17, 2014 · 7 comments

Warning about trigraph on generated assembly code #6373

vicuna opened this issue Apr 17, 2014 · 7 comments


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vicuna commented Apr 17, 2014

Original bug ID: 6373
Reporter: @damiendoligez
Assigned to: @mshinwell
Status: resolved (set by @mshinwell on 2017-03-10T11:02:17Z)
Resolution: duplicate
Priority: low
Severity: tweak
OS: Mac OS X
OS Version: 10.7.5
Version: 4.02.0+dev
Target version: undecided
Category: back end (clambda to assembly)

Bug description

String constants that contains C-style trigraphs trigger warnings from the assembler.

I've no idea why the assembler would want to interpret trigraphs or warn about them...

Steps to reproduce

----- -----

  let x = "??'"
$ ocamlopt
/tmp/camlasm5799be.s:22:10: warning: trigraph ignored [-Wtrigraphs]
        .ascii  "??'"
1 warning generated.
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vicuna commented Mar 10, 2017

Comment author: @mshinwell

Fixed by #1093

@vicuna vicuna closed this as completed Mar 10, 2017
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vicuna commented Oct 4, 2018

Comment author: pmetzger

So far as I can tell, this is not actually fixed. Running the test suite results in an error under MacOS 10.14 with Xcode 10 when I'm testing 4.07.1

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ggreif commented Oct 22, 2022

Yep, the bug is still around:

    ocamlopt mo_frontend/.mo_frontend.objs/native/mo_frontend__Parser.{cmx,o}
/tmp/build257a15.dune/camlasm457c84.s:79915:344: warning: trigraph ignored [-Wtrigraphs]
        .ascii  "\3\2\1\0[[ZYXWVVVUUUTSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSRQQPPOOOOOOOOOOOOOOOOOOOOOOOOOOOOONNNNNNNNNNNNNNNNNNNNNNNNNNNNNMMMMLLKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJIIHHGGGGFFFFEEEDDCCCCCCCCCBBBBBBBBBAAAAAAAAAAAAAAA@@@@@@@@@@@@@@@??>=<<;;;;;;:988776654321000//..--,,,,+++++++**))(((('''&&&&%%%%$$$####\42\42\42!!!    \37\37\37\36\36\36\36\35\35\35\35\34\34\34\33\33\33\32\32\32\32\31\31\31\31\30\30\30\27\27\27\27\26\26\26\25\25\25\24\24\24\23\23\22\21\21\21\20\17\17\16\16\15\15\15\15\15\15\14\14\13\13\13\13\13\13\13\13\13\12\12\12\12\12\12\11\10\10\10\10\10\10\7\6\6\5\5\4\4\4\4"

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Could you tell us more about your OS and your versions of OCaml and C compilers ?

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ggreif commented Jan 19, 2023


This is macOS version 12.6.1

$ ocaml --version
The OCaml toplevel, version 4.12.1

I am using nix, so not sure which version of Clang causes the warning, maybe this one:

/nix/store/mx8m9bs2s3wpgir5vf4crzhwgk91zj0d-clang-13.0.1-dev/include/clang/Basic/, CLASS_WARNING, (unsigned)diag::Severity::Warning, "trigraph ignored", 799, SFINAE_Suppress, false, false, false, 1)

How can I trick ocaml into disclosing this information?

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gasche commented Jan 19, 2023

ocamlc -config has c_compiler and other _c_ related configuration variables.

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ggreif commented Jan 19, 2023


$ ocamlc -config
version: 4.12.1
standard_library_default: /nix/store/2gy98d2l6bp2w2j330z4c7h08nnwbrhy-ocaml-4.12.1/lib/ocaml
standard_library: /nix/store/2gy98d2l6bp2w2j330z4c7h08nnwbrhy-ocaml-4.12.1/lib/ocaml
ccomp_type: cc
c_compiler: clang
ocamlc_cflags: -O2 -fno-strict-aliasing -fwrapv  
ocamlc_cppflags: -D_FILE_OFFSET_BITS=64 -D_REENTRANT 
ocamlopt_cflags: -O2 -fno-strict-aliasing -fwrapv  
ocamlopt_cppflags: -D_FILE_OFFSET_BITS=64 -D_REENTRANT 
bytecomp_c_compiler: clang -O2 -fno-strict-aliasing -fwrapv   -D_FILE_OFFSET_BITS=64 -D_REENTRANT 
native_c_compiler: clang -O2 -fno-strict-aliasing -fwrapv   -D_FILE_OFFSET_BITS=64 -D_REENTRANT 
bytecomp_c_libraries: -lm  -lpthread 
native_c_libraries: -lm 
native_pack_linker: ld -r -o 
ranlib: ranlib
architecture: arm64
model: default
int_size: 63
word_size: 64
system: macosx
asm: /nix/store/pkj7gr8h118xzmi7phkgirrll3vvrssj-clang-wrapper-11.1.0/bin/cc -c
asm_cfi_supported: true
with_frame_pointers: false
ext_obj: .o
ext_asm: .s
ext_lib: .a
ext_dll: .so
os_type: Unix
default_executable_name: a.out
systhread_supported: true
host: aarch64-apple-darwin21.6.0
target: aarch64-apple-darwin21.6.0
flambda: false
safe_string: true
default_safe_string: true
flat_float_array: true
function_sections: false
afl_instrument: false
windows_unicode: false
supports_shared_libraries: true
exec_magic_number: Caml1999X029
cmi_magic_number: Caml1999I029
cmo_magic_number: Caml1999O029
cma_magic_number: Caml1999A029
cmx_magic_number: Caml1999Y029
cmxa_magic_number: Caml1999Z029
ast_impl_magic_number: Caml1999M029
ast_intf_magic_number: Caml1999N029
cmxs_magic_number: Caml1999D029
cmt_magic_number: Caml1999T029
linear_magic_number: Caml1999L029

@damiendoligez some of the compiler flags should contain -Wno-trigraphs, presumably...

A quick search only turned up this (maybe the backslash technique could also work).

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