I just got annoyed enough about missing a warning that an .el file is newer than an .elc file to want to file a bug report, and sure enough found this issue has already been discussed.
To summarize the discussion so far, the following reasons have been advanced for not wanting automatically to prefer a newer .el over an older .elc:
1. One might be working on the .el file, and not want to load it yet.
2. This is a bug, which should be fixed by recompiling the .el.
Several workarounds have been proposed for those who want to use the newest version of the .el; they all involve recompiling the file (which some people complained slowed things down too much, and others pointed out could lead to loops when working on a large project), and all involve taking action for specific files, e.g. per-project, or per-file, or per-directory.
I think it's worth looking at those objections again in a modern context:
1. We don't work on deployed code any more (or shouldn't!). We use version control systems, we run tests before deploying. When I fiddle with a file, I always want my changes to take effect instantly: either I'm working on code I'm developing, or I'm trying a fix on a deployed file (and am willing to keep the bits if it breaks!).
2. GNU distributions go to some lengths to ensure that all system-installed .el files are compiled and up-to-date. el-get does the same for user-installed packages. There's little else.
Meanwhile, the workarounds require almost as much effort to install and maintain as simply remembering to byte-compile everything.
Personally, I have wasted hours by thinking I'm loading a new .el when I'm loading an old .elc, plus going through various recompilation dances when I do remember. The time that defaulting to .elc has saved me is minimal, owing to Debian+el-get taking care of recompilation.
Hence, could we have a preference that reverses the behavior, i.e. when the .el is newer, it is loaded, and a warning emitted? The default behavior should of course remain the same. It's a simple, uniform, discoverable solution. I'd happily work up a patch myself. The preference could be used in .dir-locals.el by users who preferred to switch it on only for, say, per-user site-lisp directories or project directories.
How about: load-el-when-newer (defaults to nil) ?
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