[llvm] [lit] Add JSON diffing support to lit (PR #177513)

[Henrik G. Olsson via llvm-commits]

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@@ -0,0 +1,7 @@
+# Test error handling for missing files
+
+# RUN: not json-diff %S/nonexistent.json %S/dummy.json 2>&1 | FileCheck %s --check-prefix=ERROR1
+# ERROR1: Error: failed to read JSON from
+
+# RUN: not json-diff %S/dummy.json %S/nonexistent.json 2>&1 | FileCheck %s --check-prefix=ERROR2
+# ERROR2: Error: failed to read JSON from
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hnrklssn wrote:

ditto

https://github.com/llvm/llvm-project/pull/177513