unikernel/duniverse/ppxlib/test/driver/error_embedding/dune

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+(executables
+ (names raiser pp)
+ (libraries ppxlib))
+
+(cram
+ (package ppxlib)
+ (deps raiser.exe pp.exe))

unikernel/duniverse/ppxlib/test/driver/error_embedding/pp.ml

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+let () = Ppxlib.Location.raise_errorf "Raising inside the preprocessor"

unikernel/duniverse/ppxlib/test/driver/error_embedding/raiser.ml

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+open Ppxlib
+
+let rule =
+  let expand ~loc ~path:_ =
+    Location.raise_errorf ~loc "Raising inside the rewriter"
+  in
+  Extension.declare "raise" Extension.Context.expression
+    Ast_pattern.(pstr nil)
+    expand
+  |> Context_free.Rule.extension
+
+let () = Driver.register_transformation ~rules:[ rule ] "test"
+let () = Driver.standalone ()

unikernel/duniverse/ppxlib/test/driver/error_embedding/test.t/run.t

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+Keep the error output short in order to avoid different error output between
+different compiler versions in the subsequent tests
+
+  $ export OCAML_ERROR_STYLE=short
+
+With the `-embed-errors` options, if a PPX raises, the first such exception
+is caught and prepended to the last valid AST
+
+  $ echo "let _ = [%raise]" > impl.ml
+  $ ../raiser.exe -embed-errors impl.ml
+  let _ = [%ocaml.error "Raising inside the rewriter"]
+
+The same is true when using the `-as-ppx` mode (note that the error is reported
+by ocaml itself)
+
+  $ ocaml -ppx '../raiser.exe -as-ppx' impl.ml
+  File "./impl.ml", line 1, characters 8-16:
+  Error: Raising inside the rewriter
+  [2]
+
+Also exceptions raised in a preprocessor get embedded into an AST(while the
+error from the preprocessor's stderr also gets reported on the driver's stderr)
+
+  $ touch file.ml
+  $ ../raiser.exe -embed-errors -pp ../pp.exe file.ml | sed "s/> '.*'/> tmpfile/"
+  Fatal error: exception Raising inside the preprocessor
+  [%%ocaml.error
+    "Error while running external preprocessor\nCommand line: ../pp.exe 'file.ml' > tmpfile\n"]
+
+Also `unknown version` errors are embedded into an AST when using the
+main standalone
+
+  $ ../raiser.exe -embed-errors -intf unknown_version_binary_ast
+  [%%ocaml.error
+    "File is a binary ast for an unknown version of OCaml with magic number 'Caml1999N012'"]
+
+... but the `-as-ppx` standalone raises them
+
+  $ ../raiser.exe -as-ppx unknown_version_binary_ast output
+  File "unknown_version_binary_ast", line 1:
+  Error: The input is a binary ast for an unknown version of OCaml with magic number 'Caml1999N012'
+  [1]
+
+Similar for 'input doesn't exist' errors: they get embedded by the main standalone...
+
+  $ ../raiser.exe -embed-errors -impl non_existing_file
+  [%%ocaml.error "I/O error: non_existing_file: No such file or directory"]
+
+... but not by the `-as-ppx` standalone
+
+  $ ../raiser.exe -as-ppx non_existing_file output
+  File "non_existing_file", line 1:
+  Error: I/O error: non_existing_file: No such file or directory
+  [1]