Fix Ctrl+Q for stack traces (#36344)

* alternative fix for #36340
* refactor method hint mechanism
* make LAST_SHOWN_LINE_INFOS lowercase
* implement style suggestion from @KristofferC
* fix use of LAST_SHOWN_LINE_INFOS on latest master

base/errorshow.jl

@@ -699,8 +699,8 @@ function print_stackframe(io, i, frame, n, digit_align_width, modulecolor)
 
     # Used by the REPL to make it possible to open
     # the location of a stackframe/method in the editor.
-    if haskey(io, :LAST_SHOWN_LINE_INFOS)
-        push!(io[:LAST_SHOWN_LINE_INFOS], (string(frame.file), frame.line))
+    if haskey(io, :last_shown_line_infos)
+        push!(io[:last_shown_line_infos], (string(frame.file), frame.line))
     end
 
     inlined = getfield(frame, :inlined)
@@ -749,8 +749,8 @@ end
 
 
 function show_backtrace(io::IO, t::Vector)
-    if haskey(io, :LAST_SHOWN_LINE_INFOS)
-        resize!(io[:LAST_SHOWN_LINE_INFOS], 0)
+    if haskey(io, :last_shown_line_infos)
+        empty!(io[:last_shown_line_infos])
     end
 
     # t is a pre-processed backtrace (ref #12856)

base/methodshow.jl

@@ -240,17 +240,20 @@ function show_method_table(io::IO, ms::MethodList, max::Int=-1, header::Bool=tru
     end
     n = rest = 0
     local last
-    LAST_SHOWN_LINE_INFOS = get(io, :LAST_SHOWN_LINE_INFOS, Tuple{String,Int}[])
 
-    resize!(LAST_SHOWN_LINE_INFOS, 0)
+    last_shown_line_infos = get(io, :last_shown_line_infos, nothing)
+    last_shown_line_infos === nothing || empty!(last_shown_line_infos)
+
     for meth in ms
         if max==-1 || n<max
             n += 1
             println(io)
             print(io, "[$n] ")
             show(io, meth)
             file, line = updated_methodloc(meth)
-            push!(LAST_SHOWN_LINE_INFOS, (string(file), line))
+            if last_shown_line_infos !== nothing
+                push!(last_shown_line_infos, (string(file), line))
+            end
         else
             rest += 1
             last = meth
@@ -374,16 +377,18 @@ show(io::IO, mime::MIME"text/html", mt::Core.MethodTable) = show(io, mime, Metho
 
 # pretty-printing of AbstractVector{Method}
 function show(io::IO, mime::MIME"text/plain", mt::AbstractVector{Method})
-    LAST_SHOWN_LINE_INFOS = get(io, :LAST_SHOWN_LINE_INFOS, Tuple{String,Int}[])
-    resize!(LAST_SHOWN_LINE_INFOS, 0)
+    last_shown_line_infos = get(io, :last_shown_line_infos, nothing)
+    last_shown_line_infos === nothing || empty!(last_shown_line_infos)
     first = true
     for (i, m) in enumerate(mt)
         first || println(io)
         first = false
         print(io, "[$(i)] ")
         show(io, m)
         file, line = updated_methodloc(m)
-        push!(LAST_SHOWN_LINE_INFOS, (string(file), line))
+        if last_shown_line_infos !== nothing
+            push!(last_shown_line_infos, (string(file), line))
+        end
     end
 end
 

stdlib/REPL/src/REPL.jl

@@ -204,37 +204,26 @@ end
 ==(a::REPLDisplay, b::REPLDisplay) = a.repl === b.repl
 
 function display(d::REPLDisplay, mime::MIME"text/plain", x)
-    io = outstream(d.repl)
-    get(io, :color, false) && write(io, answer_color(d.repl))
-    if isdefined(d.repl, :options) && isdefined(d.repl.options, :iocontext)
-        # this can override the :limit property set initially
-        io = foldl(IOContext, d.repl.options.iocontext,
-                   init=IOContext(io, :limit => true, :module => Main))
-    end
-
-    infos = Tuple{String,Int}[]
-    io = IOContext(io, :LAST_SHOWN_LINE_INFOS => infos)
-
-    show(io, mime, x)
-    println(io)
-
-    if !isempty(infos)
-        d.repl.last_shown_line_infos = infos
-        println(
-            io,
-            "\nTo edit a specific method, type the corresponding number into the " *
-            "REPL and press Ctrl+Q",
-        )
+    with_methodtable_hint(d.repl) do io
+        get(io, :color, false) && write(io, answer_color(d.repl))
+        if isdefined(d.repl, :options) && isdefined(d.repl.options, :iocontext)
+            # this can override the :limit property set initially
+            io = foldl(IOContext, d.repl.options.iocontext,
+                       init=IOContext(io, :limit => true, :module => Main))
+        end
+        show(io, mime, x)
+        println(io)
     end
-
     nothing
 end
 display(d::REPLDisplay, x) = display(d, MIME("text/plain"), x)
 
 function print_response(repl::AbstractREPL, @nospecialize(response), show_value::Bool, have_color::Bool)
     repl.waserror = response[2]
-    io = IOContext(outstream(repl), :module => Main)
-    print_response(io, response, show_value, have_color, specialdisplay(repl))
+    with_methodtable_hint(repl) do io
+        io = IOContext(io, :module => Main)
+        print_response(io, response, show_value, have_color, specialdisplay(repl))
+    end
     nothing
 end
 function print_response(errio::IO, @nospecialize(response), show_value::Bool, have_color::Bool, specialdisplay=nothing)
@@ -495,6 +484,22 @@ function complete_line(c::LatexCompletions, s)
     return unique!(map(completion_text, ret)), partial[range], should_complete
 end
 
+with_methodtable_hint(f, repl) = f(outstream(repl))
+function with_methodtable_hint(f, repl::LineEditREPL)
+    linfos = Tuple{String,Int}[]
+    io = IOContext(outstream(repl), :last_shown_line_infos => linfos)
+    f(io)
+    if !isempty(linfos)
+        repl.last_shown_line_infos = linfos
+        println(
+            io,
+            "\nTo edit a specific method, type the corresponding number into the " *
+            "REPL and press Ctrl+Q",
+        )
+    end
+    nothing
+end
+
 mutable struct REPLHistoryProvider <: HistoryProvider
     history::Vector{String}
     history_file::Union{Nothing,IO}

stdlib/REPL/test/repl.jl

@@ -1240,3 +1240,45 @@ frontend_task = @async begin
 end
 REPL.start_repl_backend(backend)
 Base.wait(frontend_task)
+
+macro throw_with_linenumbernode(err)
+    Expr(:block, LineNumberNode(42, Symbol("test.jl")), :(() -> throw($err)))
+end
+
+@testset "last shown line infos" begin
+    out_stream = IOBuffer()
+    term = REPL.TTYTerminal("dumb", IOBuffer(), out_stream, IOBuffer())
+    repl = REPL.LineEditREPL(term, false)
+    repl.specialdisplay = REPL.REPLDisplay(repl)
+
+    REPL.print_response(repl, (methods(+), false), true, false)
+    seekstart(out_stream)
+    @test count(
+        contains(
+            "To edit a specific method, type the corresponding number into the REPL and " *
+            "press Ctrl+Q"
+        ),
+        eachline(out_stream),
+    ) == 1
+    take!(out_stream)
+
+    err = ErrorException("Foo")
+    bt = try
+        @throw_with_linenumbernode(err)()
+    catch
+        Base.catch_stack()
+    end
+
+    repl.backendref = REPL.REPLBackendRef(Channel(1), Channel(1))
+    put!(repl.backendref.response_channel, (bt, true))
+
+    REPL.print_response(repl, (err, true), true, false)
+    seekstart(out_stream)
+    @test count(
+        contains(
+            "To edit a specific method, type the corresponding number into the REPL and " *
+            "press Ctrl+Q"
+        ),
+        eachline(out_stream),
+    ) == 1
+end