From 2e0f2bf314f58ae0cd892047e0bc9de795730bb7 Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Wed, 22 Jan 2025 23:31:38 -0500
Subject: [PATCH] add --show-eval for showing where top level eval is in
 progress

---
 base/loading.jl |  6 ++++++
 base/options.jl |  1 +
 src/jloptions.c | 14 ++++++++++++++
 src/jloptions.h |  1 +
 4 files changed, 22 insertions(+)

diff --git a/base/loading.jl b/base/loading.jl
index 4193aae13b96a..45a1b78274d9c 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -2846,6 +2846,12 @@ function include_string(mapexpr::Function, mod::Module, code::AbstractString,
             # Wrap things to be eval'd in a :toplevel expr to carry line
             # information as part of the expr.
             line_and_ex.args[2] = ex
+            show_eval = JLOptions().show_eval
+            if show_eval == 2 # show everything
+                println("eval: ", line_and_ex)
+            elseif show_eval == 1 # show top location only
+                println("eval: ", line_and_ex.args[1])
+            end
             result = Core.eval(mod, line_and_ex)
         end
         return result
diff --git a/base/options.jl b/base/options.jl
index 3281ec0de98d2..047a73f1b0012 100644
--- a/base/options.jl
+++ b/base/options.jl
@@ -61,6 +61,7 @@ struct JLOptions
     heap_size_hint::UInt64
     trace_compile_timing::Int8
     trim::Int8
+    show_eval::Int8
     task_metrics::Int8
     timeout_for_safepoint_straggler_s::Int16
 end
diff --git a/src/jloptions.c b/src/jloptions.c
index 2c5a9074eb465..b91039534d721 100644
--- a/src/jloptions.c
+++ b/src/jloptions.c
@@ -152,6 +152,7 @@ JL_DLLEXPORT void jl_init_options(void)
                         0, // heap-size-hint
                         0, // trace_compile_timing
                         JL_TRIM_NO, // trim
+                        0, // show-eval
                         0, // task_metrics
                         -1, // timeout_for_safepoint_straggler_s
     };
@@ -330,6 +331,7 @@ static const char opts_hidden[]  =
     "                                               and can throw errors. With unsafe-warn warnings will be\n"
     "                                               printed for dynamic call sites that might lead to such\n"
     "                                               errors. In safe mode compile-time errors are given instead.\n"
+    " --show-eval={loc|full|no*}                    Show the expression being evaluated before eval.\n"
 ;
 
 JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
@@ -381,6 +383,7 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
            opt_gc_threads,
            opt_permalloc_pkgimg,
            opt_trim,
+           opt_show_eval,
            opt_experimental_features,
     };
     static const char* const shortopts = "+vhqH:e:E:L:J:C:it:p:O:g:m:";
@@ -450,6 +453,7 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
         { "permalloc-pkgimg",required_argument, 0, opt_permalloc_pkgimg },
         { "heap-size-hint",  required_argument, 0, opt_heap_size_hint },
         { "trim",  optional_argument, 0, opt_trim },
+        { "show-eval",       optional_argument, 0, opt_show_eval },
         { 0, 0, 0, 0 }
     };
 
@@ -994,6 +998,16 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
             else
                 jl_errorf("julia: invalid argument to --trim={safe|no|unsafe|unsafe-warn} (%s)", optarg);
             break;
+        case opt_show_eval:
+            if (optarg == NULL || !strcmp(optarg,"loc"))
+                jl_options.show_eval = 1;
+            else if (!strcmp(optarg,"full"))
+                jl_options.show_eval = 2;
+            else if (!strcmp(optarg,"no"))
+                jl_options.show_eval = 0;
+            else
+                jl_errorf("julia: invalid argument to --show-eval={yes|no} (%s)", optarg);
+            break;
         case opt_task_metrics:
             if (!strcmp(optarg, "no"))
                 jl_options.task_metrics = JL_OPTIONS_TASK_METRICS_OFF;
diff --git a/src/jloptions.h b/src/jloptions.h
index a8cc4a9a9e33d..853bc46d3e437 100644
--- a/src/jloptions.h
+++ b/src/jloptions.h
@@ -65,6 +65,7 @@ typedef struct {
     uint64_t heap_size_hint;
     int8_t trace_compile_timing;
     int8_t trim;
+    int8_t show_eval;
     int8_t task_metrics;
     int16_t timeout_for_safepoint_straggler_s;
 } jl_options_t;