Use period-correct GCC toolchains for old Clang releases (3.1-4.0) (#5276)gh-8189

To make it consistent with newer Clang releases, all Clang assertion
builds, and user expectations.

The problem
========
Release Clang builds 3.1 through 4.0.1 are using newer GCC 6.3.0
toolchain by default. Major GCC 6.1 release happened 2.5 years after
Clang 3.1 release, which makes Clang 3.1 on CE non-period-correct
experience. We at LLVM were bitten by that while trying to triage old
Clang bugs, so I claim that current experience is off from user
expectations.

Starting with release builds of Clang 5, CE defaults to latest GCC
release for toolchain, providing period-correct experience. That makes
old Clang builds inconsistent with your current policy regarding newer
release Clang builds.

Recently introduced Clang builds with assertions enabled use
period-correct GCC toolchains in all versions, because period-correct
Clang experience is paramount for triaging old bugs. Old release builds
are not consistent with that either, which by default leads to a
difference in compiler output that doesn't come from _just_ enabling
assertions.

The solution
========
I think the best long-term solution is to fix this inconsistency, using
the same period-correct GCC toolchains as assertion builds.

This would change output in the links that rely on the difference
between old and new GCC standard library. I'd estimate that number of
such links is not high. I'd argue that if something worked there, it
shouldn't have in the first place.

---------

Co-authored-by: Vlad Serebrennikov <serebrennnikov.vladislav@gmail.com>

1 files changed, 18 insertions, 16 deletions

diff --git a/etc/config/c++.amazon.properties b/etc/config/c++.amazon.properties
index b8c0bcfb3..819433a0d 100644
--- a/etc/config/c++.amazon.properties
+++ b/etc/config/c++.amazon.properties
@@ -223,59 +223,62 @@ group.clang.compilerCategories=clang
 compiler.clang30.exe=/opt/compiler-explorer/clang+llvm-3.0-x86_64-linux-Ubuntu-11_10/bin/clang++
 compiler.clang30.alias=/usr/bin/clang++
 compiler.clang30.semver=3.0.0
-compiler.clang30.options=
+compiler.clang30.options=-I/opt/compiler-explorer/gcc-4.6.4/lib/gcc/x86_64-linux-gnu/4.6.4/include -I/opt/compiler-explorer/gcc-4.6.4/include/c++/4.6.4 -I/opt/compiler-explorer/gcc-4.6.4/include/c++/4.6.4/x86_64-linux-gnu/
 compiler.clang30.supportsBinary=false
-# Older clangs don't support anything newer than GCC's 6.3
+# Clang 3.1 and above: let's try the latest stable GCC as of the time of build
 compiler.clang31.exe=/opt/compiler-explorer/clang+llvm-3.1-x86_64-linux-ubuntu_12.04/bin/clang++
 compiler.clang31.semver=3.1
-compiler.clang31.options=-gcc-toolchain /opt/compiler-explorer/gcc-6.3.0
+compiler.clang31.options=-gcc-toolchain /opt/compiler-explorer/gcc-4.7.4
 compiler.clang31.supportsBinary=false
 compiler.clang32.exe=/opt/compiler-explorer/clang-3.2/bin/clang++
 compiler.clang32.alias=/opt/clang-3.2/bin/clang++
 compiler.clang32.semver=3.2
-compiler.clang32.options=-gcc-toolchain /opt/compiler-explorer/gcc-6.3.0
+compiler.clang32.options=-gcc-toolchain /opt/compiler-explorer/gcc-4.7.4
 compiler.clang32.supportsBinary=false
 compiler.clang33.exe=/opt/compiler-explorer/clang-3.3/bin/clang++
 compiler.clang33.alias=/opt/clang-3.3/bin/clang++
 compiler.clang33.semver=3.3
-compiler.clang33.options=-gcc-toolchain /opt/compiler-explorer/gcc-6.3.0
+compiler.clang33.options=-gcc-toolchain /opt/compiler-explorer/gcc-4.8.5
 compiler.clang341.exe=/opt/compiler-explorer/clang+llvm-3.4.1-x86_64-unknown-ubuntu12.04/bin/clang++
 compiler.clang341.alias=/opt/clang+llvm-3.4.1-x86_64-unknown-ubuntu12.04/bin/clang++
 compiler.clang341.semver=3.4.1
-compiler.clang341.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang341.options=--gcc-toolchain=/opt/compiler-explorer/gcc-4.8.5
 compiler.clang350.exe=/opt/compiler-explorer/clang+llvm-3.5.0-x86_64-linux-gnu/bin/clang++
 compiler.clang350.semver=3.5
-compiler.clang350.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang350.options=--gcc-toolchain=/opt/compiler-explorer/gcc-4.9.4
 compiler.clang351.exe=/opt/compiler-explorer/clang+llvm-3.5.1-x86_64-linux-gnu/bin/clang++
 compiler.clang351.semver=3.5.1
-compiler.clang351.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang351.options=--gcc-toolchain=/opt/compiler-explorer/gcc-4.9.4
 compiler.clang352.exe=/opt/compiler-explorer/clang+llvm-3.5.2-x86_64-linux-gnu/bin/clang++
 compiler.clang352.semver=3.5.2
-compiler.clang352.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang352.options=--gcc-toolchain=/opt/compiler-explorer/gcc-4.9.4
 compiler.clang36x.exe=/opt/compiler-explorer/clang+llvm-3.6.2-x86_64-linux-gnu-ubuntu-14.04/bin/clang++
 compiler.clang36x.semver=3.6
-compiler.clang36x.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang36x.options=--gcc-toolchain=/opt/compiler-explorer/gcc-4.9.4
 compiler.clang37x.exe=/opt/compiler-explorer/clang+llvm-3.7.0-x86_64-linux-gnu-ubuntu-14.04/bin/clang++
 compiler.clang37x.semver=3.7
-compiler.clang37x.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang37x.options=--gcc-toolchain=/opt/compiler-explorer/gcc-5.5.0
 compiler.clang371.exe=/opt/compiler-explorer/clang+llvm-3.7.1-x86_64-linux-gnu-ubuntu-14.04/bin/clang++
 compiler.clang371.semver=3.7.1
-compiler.clang371.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang371.options=--gcc-toolchain=/opt/compiler-explorer/gcc-5.5.0
 compiler.clang380.exe=/opt/compiler-explorer/clang+llvm-3.8.0-x86_64-linux-gnu-ubuntu-14.04/bin/clang++
 compiler.clang380.semver=3.8
-compiler.clang380.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
+compiler.clang380.options=--gcc-toolchain=/opt/compiler-explorer/gcc-5.5.0
 compiler.clang381.exe=/opt/compiler-explorer/clang+llvm-3.8.1-x86_64-linux-gnu-ubuntu-14.04/bin/clang++
 compiler.clang381.semver=3.8.1
-compiler.clang381.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
-# Clang 3.9 onwards support the newer toolchains
+compiler.clang381.options=--gcc-toolchain=/opt/compiler-explorer/gcc-5.5.0
 compiler.clang390.exe=/opt/compiler-explorer/clang+llvm-3.9.0-x86_64-linux-gnu-ubuntu-16.04/bin/clang++
 compiler.clang390.semver=3.9.0
+compiler.clang390.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
 compiler.clang391.exe=/opt/compiler-explorer/clang-3.9.1/bin/clang++
 compiler.clang391.semver=3.9.1
+compiler.clang391.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
 compiler.clang400.exe=/opt/compiler-explorer/clang-4.0.0/bin/clang++
 compiler.clang400.semver=4.0.0
+compiler.clang400.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
 compiler.clang401.exe=/opt/compiler-explorer/clang-4.0.1/bin/clang++
 compiler.clang401.semver=4.0.1
+compiler.clang401.options=--gcc-toolchain=/opt/compiler-explorer/gcc-6.3.0
 compiler.clang500.exe=/opt/compiler-explorer/clang-5.0.0/bin/clang++
 compiler.clang500.semver=5.0.0
 compiler.clang500.options=--gcc-toolchain=/opt/compiler-explorer/gcc-7.3.0
@@ -291,7 +294,6 @@ compiler.clang600.semver=6.0.0
 compiler.clang601.exe=/opt/compiler-explorer/clang-6.0.1/bin/clang++
 compiler.clang601.options=--gcc-toolchain=/opt/compiler-explorer/gcc-7.3.0
 compiler.clang601.semver=6.0.1
-# Clang 7 and above: let's try the latest stable GCC as of the time of build
 compiler.clang700.exe=/opt/compiler-explorer/clang-7.0.0/bin/clang++
 compiler.clang700.semver=7.0.0
 compiler.clang700.options=--gcc-toolchain=/opt/compiler-explorer/gcc-8.2.0