optional scoped sourcing, fix info script

- add new global variable, ::sta_scoped_source that if set to 1, causes all sourced files to be evaluated at the scope of the calling function instead of the top level (default 0). read_sdc will always be evaluated at the top-level, however.
- add info script calls in source and read_sdc so [info script] would return the correct filename

Co-authored-by: Peter <46405338+gadfort@users.noreply.github.com>
Signed-off-by: Mohamed Gaber <donn@efabless.com>

sdc/Sdc.tcl

@@ -45,7 +45,7 @@ proc_redirect read_sdc {
   set prev_filename [info script]
   try {
     info script $filename
-    source_ $filename $echo 0
+    uplevel \#0 "sta::source_ $filename $echo 0"
   } finally {
     info script $prev_filename
   }
@@ -63,6 +63,7 @@ if { ![info exists renamed_source] } {
 }
 
 set ::sta_continue_on_error 0
+set ::sta_scoped_source 0
 
 define_cmd_args "source" \
   {[-echo] [-verbose] filename [> filename] [>> filename]}
@@ -79,7 +80,7 @@ proc_redirect source {
   set prev_filename [info script]
   try {
     info script $filename
-    source_ $filename $echo $verbose
+    uplevel 1 "sta::source_ $filename $echo $verbose"
   } finally {
     info script $prev_filename
   }
@@ -118,7 +119,11 @@ proc source_ { filename echo verbose } {
       if { [string index $line end] != "\\" \
 	     && [info complete $cmd] } {
 	set error {}
-	set error_code [catch {uplevel \#0 $cmd} result]
+  set source_uplevel "\#0"
+  if { $::sta_scoped_source } {
+    set source_uplevel "1"
+  }
+	set error_code [catch {uplevel $source_uplevel $cmd} result]
 	# cmd consumed
 	set cmd ""
 	# Flush results printed outside tcl to stdout/stderr.

test/regression_vars.tcl

@@ -151,6 +151,7 @@ record_sta_tests {
   report_checks_src_attr
   report_json1
   report_json2
+  scoped_source
   suppress_msg
   verilog_attribute
 }

test/scoped_source.ok

@@ -0,0 +1,2 @@
+Test String: foo
+Test String: bar

test/scoped_source.tcl

@@ -0,0 +1,12 @@
+set test_string foo
+
+proc source_file {} {
+    set test_string bar
+    source ./scoped_sourceable.tcl    
+}
+
+source_file
+
+set ::sta_scoped_source 1
+
+source_file

test/scoped_sourceable.tcl

@@ -0,0 +1 @@
+puts "Test String: $test_string"