Add stacktrace colors to showing MethodErrors and method lists (JuliaLang#45069)

* Add color pass to MethodError showing, like in stacktraces

Co-authored-by: Sukera <[email protected]>

Author: Seelengrab

NEWS.md

@@ -170,4 +170,7 @@ External dependencies
 Tooling Improvements
 ---------------------
 
+* Printing of `MethodError` and methods (such as from `methods(my_func)`) are now prettified and color consistent with printing of methods
+  in stacktraces. ([#45069])
+
 <!--- generated by NEWS-update.jl: -->

base/deprecated.jl

@@ -39,16 +39,17 @@ old (generic function with 1 method)
 Calls to `@deprecate` without explicit type-annotations will define deprecated methods
 accepting arguments of type `Any`. To restrict deprecation to a specific signature, annotate
 the arguments of `old`. For example,
-```jldoctest; filter = r"in Main at.*"
+```jldoctest; filter = r"@ .*"
 julia> new(x::Int) = x;
 
 julia> new(x::Float64) = 2x;
 
 julia> @deprecate old(x::Int) new(x);
 
 julia> methods(old)
-# 1 method for generic function "old":
-[1] old(x::Int64) in Main at deprecated.jl:70
+# 1 method for generic function "old" from Main:
+ [1] old(x::Int64)
+     @ deprecated.jl:94
 ```
 will define and deprecate a method `old(x::Int)` that mirrors `new(x::Int)` but will not
 define nor deprecate the method `old(x::Float64)`.

base/errorshow.jl

@@ -333,7 +333,7 @@ end
 striptype(::Type{T}) where {T} = T
 striptype(::Any) = nothing
 
-function showerror_ambiguous(io::IO, meth, f, args)
+function showerror_ambiguous(io::IO, meths, f, args)
     print(io, "MethodError: ")
     show_signature_function(io, isa(f, Type) ? Type{f} : typeof(f))
     print(io, "(")
@@ -342,23 +342,25 @@ function showerror_ambiguous(io::IO, meth, f, args)
         print(io, "::", a)
         i < length(p) && print(io, ", ")
     end
-    print(io, ") is ambiguous. Candidates:")
+    println(io, ") is ambiguous.\n\nCandidates:")
     sigfix = Any
-    for m in meth
-        print(io, "\n  ", m)
+    for m in meths
+        print(io, "  ")
+        show(io, m; digit_align_width=-2)
+        println(io)
         sigfix = typeintersect(m.sig, sigfix)
     end
     if isa(unwrap_unionall(sigfix), DataType) && sigfix <: Tuple
         let sigfix=sigfix
-            if all(m->morespecific(sigfix, m.sig), meth)
+            if all(m->morespecific(sigfix, m.sig), meths)
                 print(io, "\nPossible fix, define\n  ")
                 Base.show_tuple_as_call(io, :function,  sigfix)
             else
-                println(io)
                 print(io, "To resolve the ambiguity, try making one of the methods more specific, or ")
                 print(io, "adding a new method more specific than any of the existing applicable methods.")
             end
         end
+        println(io)
     end
     nothing
 end
@@ -516,7 +518,7 @@ function show_method_candidates(io::IO, ex::MethodError, @nospecialize kwargs=()
                     file = string(method.file)
                 end
                 stacktrace_contract_userdir() && (file = contractuser(file))
-                print(iob, " at ", file, ":", line)
+
                 if !isempty(kwargs)::Bool
                     unexpected = Symbol[]
                     if isempty(kwords) || !(any(endswith(string(kword), "...") for kword in kwords))
@@ -538,6 +540,12 @@ function show_method_candidates(io::IO, ex::MethodError, @nospecialize kwargs=()
                 elseif ex.world > reinterpret(UInt, method.deleted_world)
                     print(iob, " (method deleted before this world age.)")
                 end
+                println(iob)
+
+                m = parentmodule_before_main(method.module)
+                color = get!(() -> popfirst!(STACKTRACE_MODULECOLORS), STACKTRACE_FIXEDCOLORS, m)
+                print_module_path_file(iob, m, string(file), line, color, 1)
+
                 # TODO: indicate if it's in the wrong world
                 push!(lines, (buf, right_matches))
             end
@@ -546,7 +554,7 @@ function show_method_candidates(io::IO, ex::MethodError, @nospecialize kwargs=()
 
     if !isempty(lines) # Display up to three closest candidates
         Base.with_output_color(:normal, io) do io
-            print(io, "\nClosest candidates are:")
+            print(io, "\n\nClosest candidates are:")
             sort!(lines, by = x -> -x[2])
             i = 0
             for line in lines
@@ -558,6 +566,7 @@ function show_method_candidates(io::IO, ex::MethodError, @nospecialize kwargs=()
                 i += 1
                 print(io, String(take!(line[1])))
             end
+            println(io) # extra newline for spacing to stacktrace
         end
     end
 end
@@ -573,20 +582,17 @@ end
 # replace `sf` as needed.
 const update_stackframes_callback = Ref{Function}(identity)
 
-const STACKTRACE_MODULECOLORS = [:magenta, :cyan, :green, :yellow]
+const STACKTRACE_MODULECOLORS = Iterators.Stateful(Iterators.cycle([:magenta, :cyan, :green, :yellow]))
 const STACKTRACE_FIXEDCOLORS = IdDict(Base => :light_black, Core => :light_black)
 
 function show_full_backtrace(io::IO, trace::Vector; print_linebreaks::Bool)
     num_frames = length(trace)
     ndigits_max = ndigits(num_frames)
 
-    modulecolordict = copy(STACKTRACE_FIXEDCOLORS)
-    modulecolorcycler = Iterators.Stateful(Iterators.cycle(STACKTRACE_MODULECOLORS))
-
     println(io, "\nStacktrace:")
 
     for (i, (frame, n)) in enumerate(trace)
-        print_stackframe(io, i, frame, n, ndigits_max, modulecolordict, modulecolorcycler)
+        print_stackframe(io, i, frame, n, ndigits_max, STACKTRACE_FIXEDCOLORS, STACKTRACE_MODULECOLORS)
         if i < num_frames
             println(io)
             print_linebreaks && println(io)
@@ -646,15 +652,12 @@ function show_reduced_backtrace(io::IO, t::Vector)
 
     ndigits_max = ndigits(length(t))
 
-    modulecolordict = Dict{Module, Symbol}()
-    modulecolorcycler = Iterators.Stateful(Iterators.cycle(STACKTRACE_MODULECOLORS))
-
     push!(repeated_cycle, (0,0,0)) # repeated_cycle is never empty
     frame_counter = 1
     for i in 1:length(displayed_stackframes)
         (frame, n) = displayed_stackframes[i]
 
-        print_stackframe(io, frame_counter, frame, n, ndigits_max, modulecolordict, modulecolorcycler)
+        print_stackframe(io, frame_counter, frame, n, ndigits_max, STACKTRACE_FIXEDCOLORS, STACKTRACE_MODULECOLORS)
 
         if i < length(displayed_stackframes)
             println(io)
@@ -684,22 +687,24 @@ end
 # from `modulecolorcycler`.
 function print_stackframe(io, i, frame::StackFrame, n::Int, digit_align_width, modulecolordict, modulecolorcycler)
     m = Base.parentmodule(frame)
-    if m !== nothing
-        while parentmodule(m) !== m
-            pm = parentmodule(m)
-            pm == Main && break
-            m = pm
-        end
-        if !haskey(modulecolordict, m)
-            modulecolordict[m] = popfirst!(modulecolorcycler)
-        end
-        modulecolor = modulecolordict[m]
+    modulecolor = if m !== nothing
+        m = parentmodule_before_main(m)
+        get!(() -> popfirst!(modulecolorcycler), modulecolordict, m)
     else
-        modulecolor = :default
+        :default
     end
     print_stackframe(io, i, frame, n, digit_align_width, modulecolor)
 end
 
+# Gets the topmost parent module that isn't Main
+function parentmodule_before_main(m)
+    while parentmodule(m) !== m
+        pm = parentmodule(m)
+        pm == Main && break
+        m = pm
+    end
+    m
+end
 
 # Print a stack frame where the module color is set manually with `modulecolor`.
 function print_stackframe(io, i, frame::StackFrame, n::Int, digit_align_width, modulecolor)
@@ -727,32 +732,33 @@ function print_stackframe(io, i, frame::StackFrame, n::Int, digit_align_width, m
     end
     println(io)
 
-    # @
-    printstyled(io, " " ^ (digit_align_width + 2) * "@ ", color = :light_black)
+    # @ Module path / file : line
+    print_module_path_file(io, modul, file, line, modulecolor, digit_align_width)
+
+    # inlined
+    printstyled(io, inlined ? " [inlined]" : "", color = :light_black)
+end
+
+function print_module_path_file(io, modul, file, line, modulecolor = :light_black, digit_align_width = 0)
+    printstyled(io, " " ^ (digit_align_width + 2) * "@", color = :light_black)
 
     # module
-    if modul !== nothing
-        printstyled(io, modul, color = modulecolor)
+    if modul !== nothing && modulecolor !== nothing
         print(io, " ")
+        printstyled(io, modul, color = modulecolor)
     end
 
     # filepath
-    pathparts = splitpath(file)
-    folderparts = pathparts[1:end-1]
-    if !isempty(folderparts)
-        printstyled(io, joinpath(folderparts...) * (Sys.iswindows() ? "\\" : "/"), color = :light_black)
-    end
+    stacktrace_expand_basepaths() && (file = something(find_source_file(file), file))
+    stacktrace_contract_userdir() && (file = contractuser(file))
+    print(io, " ")
+    dir = dirname(file)
+    !isempty(dir) && printstyled(io, dir, Filesystem.path_separator, color = :light_black)
 
     # filename, separator, line
-    # use escape codes for formatting, printstyled can't do underlined and color
-    # codes are bright black (90) and underlined (4)
-    printstyled(io, pathparts[end], ":", line; color = :light_black, underline = true)
-
-    # inlined
-    printstyled(io, inlined ? " [inlined]" : "", color = :light_black)
+    printstyled(io, basename(file), ":", line; color = :light_black, underline = true)
 end
 
-
 function show_backtrace(io::IO, t::Vector)
     if haskey(io, :last_shown_line_infos)
         empty!(io[:last_shown_line_infos])

base/methodshow.jl

@@ -59,8 +59,7 @@ function arg_decl_parts(m::Method, html=false)
         push!(tv, sig.var)
         sig = sig.body
     end
-    file = m.file
-    line = m.line
+    file, line = updated_methodloc(m)
     argnames = method_argnames(m)
     if length(argnames) >= m.nargs
         show_env = ImmutableDict{Symbol, Any}()
@@ -206,34 +205,45 @@ function sym_to_string(sym)
     end
 end
 
-function show(io::IO, m::Method)
+function show(io::IO, m::Method; modulecolor = :light_black, digit_align_width = -1)
     tv, decls, file, line = arg_decl_parts(m)
     sig = unwrap_unionall(m.sig)
     if sig === Tuple
         # Builtin
-        print(io, m.name, "(...) in ", m.module)
-        return
-    end
-    print(io, decls[1][2], "(")
-    join(
-        io,
-        String[isempty(d[2]) ? d[1] : string(d[1], "::", d[2]) for d in decls[2:end]],
-        ", ",
-        ", ",
-    )
-    kwargs = kwarg_decl(m)
-    if !isempty(kwargs)
-        print(io, "; ")
-        join(io, map(sym_to_string, kwargs), ", ", ", ")
-    end
-    print(io, ")")
-    show_method_params(io, tv)
-    print(io, " in ", m.module)
-    if line > 0
-        file, line = updated_methodloc(m)
-        print(io, " at ", file, ":", line)
+        print(io, m.name, "(...)")
+        file = "none"
+        line = 0
+    else
+        print(io, decls[1][2], "(")
+
+        # arguments
+        for (i,d) in enumerate(decls[2:end])
+            printstyled(io, d[1], color=:light_black)
+            if !isempty(d[2])
+                print(io, "::")
+                print_type_bicolor(io, d[2], color=:bold, inner_color=:normal)
+            end
+            i < length(decls)-1 && print(io, ", ")
+        end
+
+        kwargs = kwarg_decl(m)
+        if !isempty(kwargs)
+            print(io, "; ")
+            for kw in kwargs
+                skw = sym_to_string(kw)
+                print(io, skw)
+                if kw != last(kwargs)
+                    print(io, ", ")
+                end
+            end
+        end
+        print(io, ")")
+        show_method_params(io, tv)
     end
-    nothing
+
+    # module & file, re-using function from errorshow.jl
+    println(io)
+    print_module_path_file(io, m.module, string(file), line, modulecolor, digit_align_width+4)
 end
 
 function show_method_list_header(io::IO, ms::MethodList, namefmt::Function)
@@ -253,16 +263,19 @@ function show_method_list_header(io::IO, ms::MethodList, namefmt::Function)
                     "builtin function"
                : # else
                     "generic function")
-        print(io, " for ", what, " ", namedisplay)
+        print(io, " for ", what, " ", namedisplay, " from ")
+
+        col = get!(() -> popfirst!(STACKTRACE_MODULECOLORS), STACKTRACE_FIXEDCOLORS, parentmodule_before_main(ms.mt.module))
+
+        printstyled(io, ms.mt.module, color=col)
     elseif '#' in sname
         print(io, " for anonymous function ", namedisplay)
     elseif mt === _TYPE_NAME.mt
         print(io, " for type constructor")
     else
         print(io, " for callable object")
     end
-    n > 0 && print(io, ":")
-    nothing
+    !iszero(n) && print(io, ":")
 end
 
 function show_method_table(io::IO, ms::MethodList, max::Int=-1, header::Bool=true)
@@ -279,12 +292,29 @@ function show_method_table(io::IO, ms::MethodList, max::Int=-1, header::Bool=tru
     last_shown_line_infos = get(io, :last_shown_line_infos, nothing)
     last_shown_line_infos === nothing || empty!(last_shown_line_infos)
 
+    modul = if mt === _TYPE_NAME.mt # type constructor
+            which(ms.ms[1].module, ms.ms[1].name)
+        else
+            mt.module
+        end
+
+    digit_align_width = length(string(max > 0 ? max : length(ms)))
+
     for meth in ms
         if max == -1 || n < max
             n += 1
             println(io)
-            print(io, "[$n] ")
-            show(io, meth)
+
+            print(io, " ", lpad("[$n]", digit_align_width + 2), " ")
+
+            modulecolor = if meth.module == modul
+                nothing
+            else
+                m = parentmodule_before_main(meth.module)
+                get!(() -> popfirst!(STACKTRACE_MODULECOLORS), STACKTRACE_FIXEDCOLORS, m)
+            end
+            show(io, meth; modulecolor)
+
             file, line = updated_methodloc(meth)
             if last_shown_line_infos !== nothing
                 push!(last_shown_line_infos, (string(file), line))
@@ -374,7 +404,7 @@ function show(io::IO, ::MIME"text/html", m::Method)
     join(
         io,
         String[
-            isempty(d[2]) ? d[1] : string(d[1], "::<b>", d[2], "</b>") for d in decls[2:end]
+            isempty(d[2]) ? string(d[1]) : string(d[1], "::<b>", d[2] , "</b>") for d in decls[2:end]
         ],
         ", ",
         ", ",