From c858978348382dcc4a76e06a9af75d875e444997 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 20 Jul 2020 12:36:27 +0300
Subject: [PATCH] cgen: add support for `-d trace_gen` too. Add `v tracev`
 command.

---
 cmd/tools/vtracev.v    | 17 +++++++++++++++++
 cmd/v/help/default.txt |  3 +++
 cmd/v/v.v              |  2 +-
 vlib/v/gen/cgen.v      |  6 ++++++
 4 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 cmd/tools/vtracev.v

diff --git a/cmd/tools/vtracev.v b/cmd/tools/vtracev.v
new file mode 100644
index 0000000000..16661881ae
--- /dev/null
+++ b/cmd/tools/vtracev.v
@@ -0,0 +1,17 @@
+module main
+
+import os
+import v.pref
+
+fn main() {
+	vexe := pref.vexe_path()
+	vroot := os.dir(vexe)
+	os.chdir(vroot)
+	os.setenv('VCOLORS', 'always', true)
+	self_idx := os.args.index('tracev')
+	args := os.args[1..self_idx]
+	args_str := args.join(' ')
+	options := if args.len > 0 { '($args_str)' } else { '' }
+	println('Compiling a `tracev` executable ${options}...')
+	os.system('$vexe -cg -d trace_parser -d trace_checker -d trace_gen -o tracev $args_str cmd/v')
+}
diff --git a/cmd/v/help/default.txt b/cmd/v/help/default.txt
index d8ea51512b..c8026e8f73 100644
--- a/cmd/v/help/default.txt
+++ b/cmd/v/help/default.txt
@@ -35,6 +35,9 @@ V supports the following commands:
 * Others:
    build             Build a V code in the provided path (the default, so you can skip the word `build`).
    translate         Translate C code to V (coming soon in 0.3).
+   tracev            Produce a tracing version of the v compiler.
+                     Use `tracev yourfile.v` when the compiler panics.
+                     NB: `tracev` is much slower and more verbose than ordinary `v`
 
 Use "v help <command>" for more information about a command, example: `v help build`, `v help build-c`
 Use "v help other" to see less frequently used commands.
diff --git a/cmd/v/v.v b/cmd/v/v.v
index 13122a2064..d4fa7320b1 100644
--- a/cmd/v/v.v
+++ b/cmd/v/v.v
@@ -12,7 +12,7 @@ import v.builder
 const (
 	simple_cmd = [
 		'fmt', 'up', 'vet',
-		'self', 'symlink', 'bin2v',
+		'self', 'tracev', 'symlink', 'bin2v',
 		'test', 'test-fmt', 'test-compiler', 'test-fixed',
 		'repl',
 		'build-tools', 'build-examples',
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 8e9cd14e2e..1b16567fff 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -559,6 +559,9 @@ pub fn (g Gen) save() {
 }
 
 pub fn (mut g Gen) write(s string) {
+	$if trace_gen ? {
+		eprintln('gen file: ${g.file.path:-30} | last_fn_c_name: ${g.last_fn_c_name:-45} | write: $s')
+	}
 	if g.indent > 0 && g.empty_line {
 		if g.indent < tabs.len {
 			g.out.write(tabs[g.indent])
@@ -573,6 +576,9 @@ pub fn (mut g Gen) write(s string) {
 }
 
 pub fn (mut g Gen) writeln(s string) {
+	$if trace_gen ? {
+		eprintln('gen file: ${g.file.path:-30} | last_fn_c_name: ${g.last_fn_c_name:-45} | writeln: $s')
+	}
 	if g.indent > 0 && g.empty_line {
 		if g.indent < tabs.len {
 			g.out.write(tabs[g.indent])