Check on return type

src/interface.jl

@@ -48,7 +48,7 @@
 end
 
 function is_already_linted(l::LintResult, filename)
     return filename in l.linted_files
 end
 
 function has_values(l::LintResult, a, b, c)
@@ -196,7 +196,7 @@
         this_annotation = annotation_for_this_line(line)
         # current_codepoint + sizeof(line) is possibly pointing at the newline that isn't
         # actually stored in `line`.
         if offset in current_codepoint:(current_codepoint + sizeof(line))
             index_in_line = offset - current_codepoint + 1 # possibly off the end by 1.
             if !isnothing(this_annotation)
                 annotation = this_annotation
@@ -276,7 +276,7 @@
     # Filter along the file content
     ss = split(hint_as_string)
     has_filename = isfile(last(ss))
     has_filename || error("Should have a filename")
 
     filename = string(last(ss))
 
@@ -295,7 +295,6 @@
         if has_no_annotation
             # No annotation, so we merely print the reported error.
             if should_print_hint(lint_result)
-                # isdefined(Main, :Infiltrator) && Main.infiltrate(@__MODULE__, Base.@locals, @__FILE__, @__LINE__)
                 print_hint(formatter, io, "Line $(line_number), column $(column):", cleaned_hint)
                 lint_result.printout_count += 1
             end
@@ -463,7 +462,7 @@
     end
 
     # If already linted, then we merely exit
     rootpath in result.linted_files && return result
 
     # If we are running Lint on a directory
     isdir(rootpath) && return _run_lint_on_dir(rootpath; result, server, io, io_violations, io_recommendations, filters, formatter)

src/linting/extended_checks.jl

@@ -55,7 +55,7 @@
     !is_there_any_star_marker && return x == y
 
     contains(x, "QQQ") && contains(y, "QQQ") &&
         throw(BothCannotHaveStarException("Cannot both $x and $y have a star marker"))
     if contains(x, "QQQ")
         reg_exp = Regex(replace(x, "QQQ" => ".*"))
         return !isnothing(match(reg_exp, y))
@@ -209,6 +209,7 @@
 struct UnreachableBranch_Extension <: ViolationExtendedRule end
 struct StringInterpolation_Extension <: ViolationExtendedRule end
 struct RelPathAPIUsage_Extension <: ViolationExtendedRule end
+struct ReturnType_Extension <: ViolationExtendedRule end
 struct NonFrontShapeAPIUsage_Extension <: ViolationExtendedRule end
 struct InterpolationInSafeLog_Extension <: RecommendationExtendedRule end
 struct UseOfStaticThreads <: ViolationExtendedRule end
@@ -268,7 +269,7 @@
 
 function get_recommendation(msg_prefix)
     m = retrieve_full_msg_from_prefix(msg_prefix)
     m in keys(is_recommendation) || return nothing
     return is_recommendation[m]
 end
 
@@ -311,7 +312,7 @@
 end
 
 function check_for_recommendation(T::DataType, msg::String)
     @assert supertype(T) in [RecommendationExtendedRule, ViolationExtendedRule]
     b = supertype(T) == RecommendationExtendedRule
     get!(is_recommendation, msg, b)
     return nothing
@@ -343,7 +344,7 @@
 
 function check(t::NThreads_Extention, x::EXPR, markers::Dict{Symbol,String})
     # Threads.nthreads() must not be used in a const field, but it is allowed elsewhere
     haskey(markers, :const) || return
     generic_check(t, x, "Threads.nthreads()", "`Threads.nthreads()` should not be used in a constant variable.")
 end
 
@@ -397,10 +398,10 @@
 check(t::Ptr_Extension, x::EXPR) = generic_check(t, x, "Ptr{hole_variable}(hole_variable)")
 
 function check(t::ArrayWithNoType_Extension, x::EXPR, markers::Dict{Symbol,String})
     haskey(markers, :filename) || return
     contains(markers[:filename], "src/Compiler") || return
 
     haskey(markers, :macrocall) && markers[:macrocall] == "@match" && return
     haskey(markers, :macrocall) && markers[:macrocall] == "@matchrule" && return
 
     generic_check(t, x, "[]", "Need a specific Array type to be provided.")
@@ -549,6 +550,16 @@
     generic_check(t, x, "relpath_from_signature(hole_variable)", "Usage of method `relpath_from_signature` is not allowed in this context.")
 end
 
+function check(t::ReturnType_Extension, x::EXPR, markers::Dict{Symbol,String})
+    # No check of return type in Arroyo
+    haskey(markers, :filename) || return
+    contains(markers[:filename], "packages/Arroyo/src/") && return
+
+    msg = "Return type are prohibited ([explanation](https://github.com/RelationalAI/RAIStyle?tab=readme-ov-file#return-type-annotations-in-function-signatures-can-cause-runtime-cost))."
+    generic_check(t, x, "hole_variable(hole_variable_star)::hole_variable = hole_variable", msg)
+    generic_check(t, x, "function hole_variable(hole_variable_star)::hole_variable hole_variable_star end", msg)
+end
+
 function check(t::NonFrontShapeAPIUsage_Extension, x::EXPR, markers::Dict{Symbol,String})
     haskey(markers, :filename) || return
     # In the front-end and in FFI, we are allowed to refer to `Shape`

test/rai_rules_tests.jl

@@ -1969,6 +1969,46 @@ end
     @test lint_test(source, "Line 10, column 17: Safe warning log has interpolation.")
 end
 
+@testset "Prohibit return types" begin
+    @testset "Case 01" begin
+        source = raw"""
+        function pm_check_mutable_pages(bytes::Int)::Bool
+            pm = PAGER_MONITOR
+
+            max_pages = (@atomic pm.mutable_pages_running_max)
+            max_bytes = (@atomic pm.mutable_bytes_running_max)
+            if max_bytes >= bytes
+                @warnv_safe_to_log 0 "[Pager] Too many mutable pages \
+                    detected: $max_pages pages weighting $max_bytes bytes"
+
+                @ensure @warnv_safe_to_log 2 "[Pager] Too many mutable pages \
+                    detected: $max_pages pages weighting $max_bytes bytes"
+
+                @ensure @warnv_safe_to_log 0 "no interpolation"
+
+                mutable_report = pm_generate_mutable_pages_report!()
+                if !isnothing(mutable_report)
+                    @warnv_safe_to_log 0 mutable_report
+                end
+                return false
+            end
+
+            return true
+        end
+        """
+        @test lint_test(source, "Line 1, column 1: Return type are prohibited")
+    end
+
+    @testset "Case 02" begin
+        source = """
+        function Base.foo()::Int
+            return 42
+        end
+        """
+        @test lint_test(source, "Line 1, column 1: Return type are prohibited")
+    end
+end
+
 @testset "Use of static threads" begin
     source = raw"""
     function f()