gh-122873: Allow "python -m json" to work (#122884)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Alyssa Coghlan <ncoghlan@gmail.com>

3 files changed, 28 insertions, 15 deletions

diff --git a/Lib/json/__init__.py b/Lib/json/__init__.py
index ed2c747..1d972d2 100644
--- a/Lib/json/__init__.py
+++ b/Lib/json/__init__.py
@@ -86,13 +86,13 @@ Specializing JSON object encoding::
     '[2.0, 1.0]'
 
 
-Using json.tool from the shell to validate and pretty-print::
+Using json from the shell to validate and pretty-print::
 
-    $ echo '{"json":"obj"}' | python -m json.tool
+    $ echo '{"json":"obj"}' | python -m json
     {
         "json": "obj"
     }
-    $ echo '{ 1.2:3.4}' | python -m json.tool
+    $ echo '{ 1.2:3.4}' | python -m json
     Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
 """
 __version__ = '2.0.9'
diff --git a/Lib/json/__main__.py b/Lib/json/__main__.py
new file mode 100644
index 0000000..1808ead
--- /dev/null
+++ b/Lib/json/__main__.py
@@ -0,0 +1,20 @@
+"""Command-line tool to validate and pretty-print JSON
+
+Usage::
+
+    $ echo '{"json":"obj"}' | python -m json
+    {
+        "json": "obj"
+    }
+    $ echo '{ 1.2:3.4}' | python -m json
+    Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
+
+"""
+import json.tool
+
+
+if __name__ == '__main__':
+    try:
+        json.tool.main()
+    except BrokenPipeError as exc:
+        raise SystemExit(exc.errno)
diff --git a/Lib/json/tool.py b/Lib/json/tool.py
index fdfc337..9028e51 100644
--- a/Lib/json/tool.py
+++ b/Lib/json/tool.py
@@ -1,14 +1,7 @@
-r"""Command-line tool to validate and pretty-print JSON
-
-Usage::
-
-    $ echo '{"json":"obj"}' | python -m json.tool
-    {
-        "json": "obj"
-    }
-    $ echo '{ 1.2:3.4}' | python -m json.tool
-    Expecting property name enclosed in double quotes: line 1 column 3 (char 2)
+"""Command-line tool to validate and pretty-print JSON
 
+See `json.__main__` for a usage example (invocation as
+`python -m json.tool` is supported for backwards compatibility).
 """
 import argparse
 import json
@@ -16,7 +9,7 @@ import sys
 
 
 def main():
-    prog = 'python -m json.tool'
+    prog = 'python -m json'
     description = ('A simple command line interface for json module '
                    'to validate and pretty-print JSON objects.')
     parser = argparse.ArgumentParser(prog=prog, description=description)
@@ -86,4 +79,4 @@ if __name__ == '__main__':
     try:
         main()
     except BrokenPipeError as exc:
-        sys.exit(exc.errno)
+        raise SystemExit(exc.errno)