Re: [gentoo-dev] Re: [PATCH] toolchain-funcs: Add tc-ld-is-lld helper.

[Ulrich Mueller <ulm@gentoo.org>]

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>>>>> On Fri, 13 Sep 2019, Manoj Gupta wrote:

>> LLD is a new linker for LLVM project.
>> Add tc-ld-is-lld helper to be able to detect it.
>> 
>> Signed-off-by: Manoj Gupta <manojgupta@google.com>
>> ---
>> eclass/toolchain-funcs.eclass | 30 ++++++++++++++++++++++++++++++
>> 1 file changed, 30 insertions(+)
>> 
>> diff --git a/eclass/toolchain-funcs.eclass b/eclass/toolchain-funcs.eclass
>> index 7bd90bb4e4a..e358d484417 100644
>> --- a/eclass/toolchain-funcs.eclass
>> +++ b/eclass/toolchain-funcs.eclass
>> @@ -453,6 +453,36 @@ tc-ld-is-gold() {
>>  return 1
>>  }
>>  
>> +# @FUNCTION: tc-ld-is-lld
>> +# @USAGE: [toolchain prefix]
>> +# @DESCRIPTION:
>> +# Return true if the current linker is set to lld.
>> +tc-ld-is-lld() {
>> +       local out
>> +
>> +       # First check the linker directly.
>> +       out=$($(tc-getLD "$@") --version 2>&1)

Why 2>&1 here, and not 2>/dev/null?

>> +       if [[ ${out} == *"LLD"* ]] ; then
>> +               return 0
>> +       fi
>> +
>> +       # Then see if they're selecting lld via compiler flags.
>> +       # Note: We're assuming they're using LDFLAGS to hold the
>> +       # options and not CFLAGS/CXXFLAGS.
>> +       local base="${T}/test-tc-lld"
>> +       cat <<-EOF > "${base}.c"
>> +       int main() { return 0; }
>> +       EOF
>> +       out=$($(tc-getCC "$@") ${CFLAGS} ${CPPFLAGS} ${LDFLAGS} -Wl,--version "${base}.c" -o "${base}" 2>&1)

Ditto.

>> +       rm -f "${base}"*
>> +       if [[ ${out} == *"LLD"* ]] ; then
>> +               return 0
>> +       fi
>> +
>> +       # No lld here!
>> +       return 1

The previous 6 lines could be shortened to one:
[[ ${out} == *"LLD"* ]]

>> +}
>> +
>>  # @FUNCTION: tc-ld-disable-gold
>>  # @USAGE: [toolchain prefix]
>>  # @DESCRIPTION:

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