[New-bugs-announce] [issue27189] configure --with-lto with clang should find the appropriate llvm-profdata tool

[Gregory P. Smith]

New submission from Gregory P. Smith:

The --with-lto support added in issue25702 can work with clang, but on a Linux distribution such as ubuntu 16.04 with clang installed you get:

$ CC=clang ./configure --with-lto
...
$ make profile-opt
Error: Cannot perform PGO build because llvm-profdata was not found in PATH
Please add it to PATH and run ./configure again
Makefile:503: recipe for target 'profile-opt' failed
make: *** [profile-opt] Error 1

The llvm-profdata tool exists but is only known as llvm-profdata-3.8.  We should have the ./configure script figure this out.  I'm not sure what the preferred "right" way to determine this is.  Detecting that CC is a clang compiler and using its reported version number?  noticing that clang is a symlink into an llvm-X.Y tree and using that number?  none of these sound great.  hopefully there is a better deterministic way to query clang for this.

----------
components: Build
messages: 266976
nosy: gregory.p.smith
priority: normal
severity: normal
stage: needs patch
status: open
title: configure --with-lto with clang should find the appropriate llvm-profdata tool
type: compile error
versions: Python 2.7, Python 3.5, Python 3.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue27189>
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