unikernel/duniverse/dune_/test/blackbox-tests/test-cases/melange/flags.t

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+Test flags and compile_flags fields on melange.emit stanza
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.8)
+  > (using melange 0.1)
+  > EOF
+
+Using flags field in melange.emit stanzas is not supported
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (emit_stdlib false)
+  >  (modules main)
+  >  (flags -w -14-26))
+  > EOF
+
+  $ dune build @mel
+  File "dune", line 5, characters 2-7:
+  5 |  (flags -w -14-26))
+        ^^^^^
+  Error: Unknown field "flags"
+  [1]
+
+Adds a module that contains unused var (warning 26) and illegal backlash (warning 14)
+
+  $ cat > main.ml <<EOF
+  > let t = "\e\n" in
+  > print_endline "hello"
+  > EOF
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (emit_stdlib false)
+  >  (modules main)
+  >  (alias mel))
+  > EOF
+
+Trying to build triggers both warnings
+
+  $ dune build @mel
+  File "main.ml", line 1, characters 9-11:
+  1 | let t = "\e\n" in
+               ^^
+  Error (warning 14 [illegal-backslash]): illegal backslash escape in string.
+  Hint: Single backslashes \ are reserved for escape sequences
+  (\n, \r, ...). Did you check the list of OCaml escape sequences?
+  To get a backslash character, escape it with a second backslash: \\.
+  File "main.ml", line 1, characters 4-5:
+  1 | let t = "\e\n" in
+          ^
+  Error (warning 26 [unused-var]): unused variable t.
+  [1]
+
+Let's ignore them using compile_flags
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (modules main)
+  >  (emit_stdlib false)
+  >  (alias mel)
+  >  (compile_flags -w -14-26))
+  > EOF
+
+  $ dune build @mel
+  $ node _build/default/output/main.js
+  hello
+
+Can also pass flags from the env stanza. Let's go back to failing state:
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (emit_stdlib false)
+  >  (modules main)
+  >  (alias mel))
+  > EOF
+
+  $ dune build @mel
+  File "main.ml", line 1, characters 9-11:
+  1 | let t = "\e\n" in
+               ^^
+  Error (warning 14 [illegal-backslash]): illegal backslash escape in string.
+  Hint: Single backslashes \ are reserved for escape sequences
+  (\n, \r, ...). Did you check the list of OCaml escape sequences?
+  To get a backslash character, escape it with a second backslash: \\.
+  File "main.ml", line 1, characters 4-5:
+  1 | let t = "\e\n" in
+          ^
+  Error (warning 26 [unused-var]): unused variable t.
+  [1]
+
+Adding env stanza with both warnings silenced allows the build to pass successfully
+
+  $ cat > dune <<EOF
+  > (env
+  >  (_
+  >   (melange.compile_flags -w -14-26)))
+  > (melange.emit
+  >  (alias mel)
+  >  (target output)
+  >  (emit_stdlib false)
+  >  (modules main))
+  > EOF
+
+  $ dune build @mel
+  $ node _build/default/output/main.js
+  hello
+
+Warning 102 (Melange only) is available if explicitly set
+
+  $ cat > main.ml <<EOF
+  > let compare a b = compare a b
+  > EOF
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (modules main)
+  >  (emit_stdlib false)
+  >  (compile_flags -w +a-70))
+  > EOF
+
+  $ dune build output/main.js
+  File "main.ml", line 1, characters 18-29:
+  1 | let compare a b = compare a b
+                        ^^^^^^^^^^^
+  Warning 102 [polymorphic-comparison-introduced]: Polymorphic comparison introduced (maybe unsafe)
+
+But it is disabled by default
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (emit_stdlib false)
+  >  (modules main))
+  > EOF
+
+  $ dune build output/main.js