Installer reports success after failing

[Paul Hargrove]

Here are last two lines of output when I ran ./install $HOME/upcxx-inst where $HOME/upcxx-inst already contains an installation:

./install: line 109: /Users/phargrov/upcxx-inst/bin/upcxx-meta: cannot overwrite existing file
UPC++ successfully installed

The failure on line 109 is apparently due to noclobber=1 in my ~/.bashrc.
So the installer could overcome this particular case by setting noclobber=0.

However, I think the important issue here is that the script is not checking for failure of some or all of the commands it runs.
So, set -e near the very beginning of the install script is probably appropriate.

This was reproduced from master and thus corresponds to the 2017.9.0 release.

[Paul Hargrove]

Self-assigning since I know how to fix and am best situated to test.

[Paul Hargrove]

install: improve error handling & avoidance

This commit resolves issue #82 by making two changes:

• Replace '>' with '>|' when creating the top-level upcxx-meta, in order to make the behavior of the script independent of the shell's noclobber setting.

• Add "trap failure_and_die ERR" to ensure that any failing shell commands (full pipelines) will result in the "Please report ..." message. This is actaully a bit more friendly than the simpler 'set -e' I had suggested in the issue tracker.

As a result of the second change, it is likely we could remove a few instances of calls directly to 'failure_and_die'. However, without the ability to test each one carefully, I have not undertaken to do so.

→ <<cset 2800995885cc>>