[lld] [LLD][COFF] Require explicit specification of ARM64EC target (PR #116281)

[Daniel Paoliello via llvm-commits]

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@@ -74,13 +77,18 @@ void SymbolTable::addFile(InputFile *file) {
   }
 
   MachineTypes mt = file->getMachineType();
+  if (!compatibleMachineType(ctx, mt)) {
+    if (isArm64EC(mt))
+      error(toString(file) + ": incompatible machine type " + machineToStr(mt) +
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dpaoliello wrote:

Not a fan of this error message: it seems odd that if the user asked for the machine type to be inferred that the linker reports that something is incompatible. Maybe say that it is ambiguous or can't be decided/inferred? 

https://github.com/llvm/llvm-project/pull/116281