Unboxed literal tests

ocaml/testsuite/tests/typing-layouts/invalid_integer_literals.compilers.reference

@@ -0,0 +1,6 @@
+
+Line 6, characters 44-47:
+6 | let unboxed_integers_must_have_a_modifier = #42
+                                                ^^^
+Error: Syntax error: literal modifier expected.
+

ocaml/testsuite/tests/typing-layouts/invalid_integer_literals.ml

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+(* TEST
+   flags = "-extension layouts_alpha"
+   * toplevel
+*)
+
+let unboxed_integers_must_have_a_modifier = #42

ocaml/testsuite/tests/typing-layouts/literals.ml

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+(* TEST
+   flags = "-extension layouts_alpha"
+   * expect
+*)
+
+let e = #2.718281828459045
+[%%expect{|
+val e : float = 2.71828182845904509
+|}]
+
+let negative_one_half = -#0.5
+[%%expect{|
+val negative_one_half : float = -0.5
+|}]
+
+let positive_one_dot = +#1.
+[%%expect{|
+val positive_one_dot : float = 1.
+|}]
+
+let one_billion = #1e9
+[%%expect{|
+val one_billion : float = 1000000000.
+|}]
+
+let zero = #0n
+[%%expect{|
+val zero : nativeint = 0n
+|}]
+
+let positive_one = +#1l
+[%%expect{|
+val positive_one : int32 = 1l
+|}]
+
+let negative_one = -#1L
+[%%expect{|
+val negative_one : int64 = -1L
+|}]
+
+let two_fifty_five_in_hex = #0xFFn
+[%%expect{|
+val two_fifty_five_in_hex : nativeint = 255n
+|}]
+
+let twenty_five_in_octal = #0o31l
+[%%expect{|
+val twenty_five_in_octal : int32 = 25l
+|}]
+
+let forty_two_in_binary = #0b101010L
+[%%expect{|
+val forty_two_in_binary : int64 = 42L
+|}]
+
+let one_twenty_seven_point_two_five_in_floating_hex = #0x7f.4
+[%%expect{|
+val one_twenty_seven_point_two_five_in_floating_hex : float = 127.25
+|}]
+
+let five_point_three_seven_five_in_floating_hexponent = #0xa.cp-1
+[%%expect{|
+val five_point_three_seven_five_in_floating_hexponent : float = 5.375
+|}]