Pipeline · Glasgow Haskell Compiler / GHC

PrelRules: Don't break let/app invariant in shiftRule

Previously shiftRule would rewrite as invalid shift like
```
let x = I# (uncheckedIShiftL# n 80)
in ...
```
to
```
let x = I# (error "invalid shift")
in ...
```
However, this breaks the let/app invariant as `error` is not
okay-for-speculation. There isn't an easy way to avoid this so let's not
try. Instead we just take advantage of the undefined nature of invalid
shifts and return zero.

Fixes #16742.

(cherry picked from commit 0bd3b9dd)

18 jobs for !1211 with wip/backport-T16742 in 285 minutes and 28 seconds (queued for 3 seconds)

fee015b5

Status	Job ID	Name
Lint
passed	#103807 lint	ghc-linters	00:00:14 Jun 15, 2019
passed	#103808 lint	lint-submods-mr	00:00:14 Jun 15, 2019

Build
failed	#103811 x86_64-linux allowed to fail	release-x86_64-linux-deb9-dwarf	01:27:26 Jun 15, 2019
passed	#103809 x86_64-linux	validate-x86_64-linux-deb8-hadrian	01:56:57 Jun 15, 2019
passed	#103810 x86_64-linux	validate-x86_64-linux-deb9-debug	00:46:09 Jun 15, 2019

Full Build
failed	#103813 aarch64-linux allowed to fail	validate-aarch64-linux-deb9	00:59:33 Jun 15, 2019
passed	#103814 x86_64-linux	validate-i386-linux-deb9	01:26:27 Jun 15, 2019
passed	#103812 x86_64-darwin	validate-x86_64-darwin	00:57:27 Jun 15, 2019
passed	#103815 x86_64-linux	validate-x86_64-linux-deb9	01:30:21 Jun 15, 2019
failed	#103817 x86_64-linux allowed to fail	validate-x86_64-linux-deb9-integer-simple	00:36:22 Jun 15, 2019
failed	#103816 x86_64-linux allowed to fail	validate-x86_64-linux-deb9-llvm	01:57:02 Jun 15, 2019
passed	#103818 x86_64-linux	validate-x86_64-linux-deb9-unreg	02:47:47 Jun 16, 2019
passed	#103819 x86_64-linux	validate-x86_64-linux-fedora27	01:32:23 Jun 15, 2019
failed	#103821 x86_64-windows allowed to fail	validate-x86_64-windows	02:20:59 Jun 15, 2019
failed	#103820 x86_64-windows allowed to fail	validate-x86_64-windows-hadrian	00:12:32 Jun 15, 2019

Cleanup
passed	#103823 x86_64-darwin	cleanup-darwin	00:00:04 Jun 16, 2019
passed	#103822 x86_64-windows	cleanup-windows	00:00:29 Jun 16, 2019

Hackage
manual	#103824 x86_64-linux allowed to fail manual	hackage

	Name	Stage
failed	validate-aarch64-linux-deb9	Full Build
	`$ cp -Rf $HOME/.cabal cabal-cache Uploading artifacts... WARNING: ghc-*.tar.xz: no matching files WARNING: junit.xml: no matching files ERROR: No files to upload Uploading artifacts... WARNING: junit.xml: no matching files ERROR: No files to upload ERROR: Job failed: exit code 1`
failed	validate-x86_64-linux-deb9-llvm	Full Build
	`make[1]: Leaving directory '/builds/ghc/ghc/testsuite/tests' Makefile:224: recipe for target 'test' failed make: *** [test] Error 2 Running after script... $ cp -Rf $HOME/.cabal cabal-cache Uploading artifacts... junit.xml: found 1 matching files Uploading artifacts to coordinator... ok id=103816 responseStatus=201 Created token=8S1FryMF ERROR: Job failed: exit code 1`
failed	validate-x86_64-windows-hadrian	Full Build
	`Speed : 93310056 Bytes/sec. Speed : 5339.244 MegaBytes/min. Ended : Saturday, June 15, 2019 9:50:42 PM Uploading artifacts... Runtime platform arch=amd64 os=windows pid=4608 revision=1f513601 version=11.10.1 WARNING: ghc.tar.xz: no matching files ERROR: No files to upload ERROR: Job failed: exit status 1`
failed	release-x86_64-linux-deb9-dwarf	Build
	`$ cp -Rf $HOME/.cabal cabal-cache Uploading artifacts... ghc-*.tar.xz: found 1 matching files junit.xml: found 1 matching files Uploading artifacts to coordinator... ok id=103811 responseStatus=201 Created token=b4xomz6s Uploading artifacts... junit.xml: found 1 matching files Uploading artifacts to coordinator... ok id=103811 responseStatus=201 Created token=b4xomz6s ERROR: Job failed: exit code 1`
failed	validate-x86_64-linux-deb9-integer-simple	Full Build
	`make[1]: * Waiting for unfinished jobs.... make: * [all] Error 2 Makefile:123: recipe for target 'all' failed Running after script... $ cp -Rf $HOME/.cabal cabal-cache Uploading artifacts... WARNING: junit.xml: no matching files ERROR: No files to upload ERROR: Job failed: exit code 1`
failed	validate-x86_64-windows	Full Build
	junit.xml: found 1 matching files WARNING: Failed to load system CertPool:crypto/x509: system root pool is not available on Windows Uploading artifacts to coordinator... ok id=103821 responseStatus=201 Created token=iQzRTDSt Uploading artifacts... Runtime platform arch=amd64 os=windows pid=4932 revision=1f513601 version=11.10.1 junit.xml: found 1 matching files WARNING: Failed to load system CertPool:crypto/x509: system root pool is not available on Windows Uploading artifacts to coordinator... ok id=103821 responseStatus=201 Created token=iQzRTDSt ERROR: Job failed: exit status 2