[clang] [WebAssembly] Clang support for exception-based lookup paths (PR #185775)

[Alex Crichton via cfe-commits]

================
@@ -34,6 +34,15 @@ std::string WebAssembly::getMultiarchTriple(const Driver &D,
             TargetTriple.getOSAndEnvironmentName()).str();
 }
 
+/// Returns a directory name in which separate objects compile with/without
+/// exceptions may lie. This is used both for `#include` paths as well as lib
+/// paths.
+static std::string GetCXXExceptionsDir(const ArgList &DriverArgs) {
+  if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions))
+    return "eh";
+  return "noeh";
----------------
alexcrichton wrote:

My thinking behind this was that if the no-eh libs are in the default location then there's a risk they're used if things are misconfigured and the `eh` path is lost. By separating these directories entirely it'd help catch misconfigurations because the libraries would be entirely missing as opposed to possibly overlapping.

For now with wasi-sdk only libcxx and friends are compiled twice, I was thinking that there'd be libc in the "default location" and then libcxx would be located both in the "eh" and "noeh" locations compiled separately

https://github.com/llvm/llvm-project/pull/185775