make show_backtrace and display_error work for Frame (#211)

make show_backtrace and display_error work for Frame

Author: KristofferC

src/types.jl

@@ -142,6 +142,11 @@ Fields:
 - `pc`: the program counter (integer index of the next statment to be evaluated) for this frame
 - `caller`: the parent caller of this frame, or `nothing`
 - `callee`: the frame called by this one, or `nothing`
+
+The `Base` functions `show_backtrace` and `display_error` are overloaded such that
+`show_backtrace(io::IO, frame::Frame)` and `display_error(io::IO, er, frame::Frame)`
+shows a backtrace or error, respectively, in a similar way as to how Base shows
+them.
 """
 mutable struct Frame
     framecode::FrameCode

src/utils.jl

@@ -338,3 +338,47 @@ function show_stackloc(io::IO, frame)
     end
 end
 show_stackloc(frame) = show_stackloc(stdout, frame)
+
+# Printing of stacktraces and errors with Frame
+function Base.StackTraces.StackFrame(frame::Frame)
+    if scopeof(frame) isa Method
+        method = frame.framecode.scope
+        method_args = something.(frame.framedata.locals[1:method.nargs])
+        atypes = Tuple{typeof.(method_args)...}
+        sig = method.sig
+        sparams = Core.svec(frame.framedata.sparams...)
+        mi = Core.Compiler.code_for_method(method, atypes, sparams, typemax(UInt))
+    else
+        mi = frame.framecode.src
+    end
+    Base.StackFrame(
+        frame.framecode.scope.name,
+        Symbol(JuliaInterpreter.getfile(frame)),
+        JuliaInterpreter.linenumber(frame),
+        mi,
+        false,
+        false,
+        C_NULL
+    )
+end
+
+function Base.show_backtrace(io::IO, frame::Frame)
+    stackframes = Tuple{Base.StackTraces.StackFrame, Int}[]
+    while frame !== nothing
+        push!(stackframes, (Base.StackTraces.StackFrame(frame), 1))
+        frame = JuliaInterpreter.caller(frame)
+    end
+    print(io, "\nStacktrace:")
+    try invokelatest(Base.update_stackframes_callback[], stackframes) catch end
+    frame_counter = 0
+    for (last_frame, n) in stackframes
+        frame_counter += 1
+        Base.show_trace_entry(IOContext(io, :backtrace => true), last_frame, n, prefix = string(" [", frame_counter, "] "))
+    end
+end
+
+function Base.display_error(io::IO, er, frame::Frame)
+    printstyled(io, "ERROR: "; bold=true, color=Base.error_color())
+    showerror(IOContext(io, :limit => true), er, frame)
+    println(io)
+end

test/interpret.jl

@@ -424,3 +424,21 @@ locs = JuliaInterpreter.locals(JuliaInterpreter.enter_call(foo, ""))
 @test @interpret subtypes(Main, Integer) == subtypes(Main, Integer)
 @test (@elapsed @interpret subtypes(Integer)) < 30
 @test (@elapsed @interpret subtypes(Main, Integer)) < 30
+
+# Test showing stacktraces from frames
+g_1(x) = g_2(x)
+g_2(x) = g_3(x)
+g_3(x) = error("foo")
+line_g = @__LINE__
+try
+    break_on(:error)
+    frame, bp = @interpret g_1(2.0)
+    stacktrace_lines = split(sprint(Base.display_error, bp.err, leaf(frame)), '\n')
+    @test occursin(string("ERROR: ", sprint(showerror, ErrorException("foo"))), stacktrace_lines[1])
+    @test occursin("[1] error(::String) at error.jl:", stacktrace_lines[3])
+    @test occursin("[2] g_3(::Float64) at $(@__FILE__):$(line_g - 1)", stacktrace_lines[4])
+    @test occursin("[3] g_2(::Float64) at $(@__FILE__):$(line_g - 2)", stacktrace_lines[5])
+    @test occursin("[4] g_1(::Float64) at $(@__FILE__):$(line_g - 3)", stacktrace_lines[6])
+finally
+    break_off(:error)
+end