development_tools: add type signatures

[FnControlOption]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
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---

Redefining the existing method DevelopmentTools.custom_installation_instructions as a method alias https://srb.help/5037
    35 |    alias custom_installation_instructions installation_instructions
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

-alias custom_installation_instructions installation_instructions
+def custom_installation_instructions
+  installation_instructions
+end

---

Expected T::Boolean but found T.nilable(Pathname) for method result type https://srb.help/7005
    29 |    end
            ^^^

 def installed?
-  locate("clang") || locate("gcc")
+  locate("clang").present? || locate("gcc").present?
 end

---

This code is unreachable https://srb.help/7006
    21 |    return false if MacOS::Xcode.version && MacOS::Xcode.version < "8.0"
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This code is unreachable https://srb.help/7006
    22 |    return false if MacOS::CLT.version && MacOS::CLT.version < "8.0"
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

-return false if MacOS::Xcode.version && MacOS::Xcode.version < "8.0"
-return false if MacOS::CLT.version && MacOS::CLT.version < "8.0"
+return false if !MacOS::Xcode.version.null? && MacOS::Xcode.version < "8.0"
+return false if !MacOS::CLT.version.null? && MacOS::CLT.version < "8.0"

[Bo98]

Given the comment here:

Suggested change

	# Returns a Pathname object corresponding to Xcode.app's Developer
	# directory or nil if Xcode.app is not installed.
	sig { returns(Pathname) }
	# Returns a Pathname object corresponding to Xcode.app's Developer
	# directory or nil if Xcode.app is not installed.
	sig { returns(T.nilable(Pathname)) }

Not entirely sure why Sorbet doesn't notice that however?

[FnControlOption]

Pathname#cleanpath returns T.untyped. Opened sorbet/sorbet#4660.

tmp = Pathname.new(dir).cleanpath
T.assert_type! tmp, Pathname
tmp

Expected a type but found T.untyped for T.assert_type! https://srb.help/7007
     106 |              T.assert_type! tmp, Pathname
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[Bo98]

Suggested change

	sig { returns(T::Hash[String, T.untyped]) }
	sig { returns(T::Hash[String, T.nilable(String)]) }

[Bo98]

Suggested change

	sig { returns(T::Hash[String, T.untyped]) }
	sig { returns(T::Hash[String, T.nilable(String)]) }

and probably append .to_s.presence to Glibc version and .to_s to oldest CPU.

[Bo98]

Suggested change

	sig { returns(T::Hash[String, T.untyped]) }
	sig { returns(T::Hash[String, T.nilable(String)]) }

and append .to_s to CPU family.

[Bo98]

Yes, I think so.

[MikeMcQuaid]

Great work! I'm happy when @Bo98 is.

[Bo98]

Thanks!