util.argparse: Fix bug (regression?) in argument parsing with --foo=bar

After recent changes, '--foo bar' was working, but '--foo=bar' was not. The
test had a typo (?) (bar != baz) and because util.argparse is not strict by
default, the typo was not caught.

The typo caused the code to take a different path, and bypassed the buggy
handling of --foo=bar options.

I've preserved the existing test (typo and all!) because it's still an
interesting test, and ensures no unintended behaviour changes compared to the
old code.

However I've added a new variant of the test, with strict mode enabled and the
typo fixed. This test failed due to the bug, and this commit introduces a fix.

2 files changed, 12 insertions, 2 deletions

diff --git a/spec/util_argparse_spec.lua b/spec/util_argparse_spec.lua
index be1d99df..3fd4070e 100644
--- a/spec/util_argparse_spec.lua
+++ b/spec/util_argparse_spec.lua
@@ -54,6 +54,12 @@ describe("parse", function()
 		assert.same({ foo = "bar"; baz = "moo" }, opts);
 	end);
 
+	it("supports value arguments in strict mode", function()
+		local opts, err = parse({ "--foo"; "bar"; "--baz=moo" }, { strict = true, value_params = { foo = true; baz = true } });
+		assert.falsy(err);
+		assert.same({ foo = "bar"; baz = "moo" }, opts);
+	end);
+
 	it("demands values for value params", function()
 		local opts, err, where = parse({ "--foo" }, { value_params = { foo = true } });
 		assert.falsy(opts);
diff --git a/util/argparse.lua b/util/argparse.lua
index 3a7d1ba2..75b1c2f9 100644
--- a/util/argparse.lua
+++ b/util/argparse.lua
@@ -39,9 +39,13 @@ local function parse(arg, config)
 
 			local param_k, param_v;
 			if value_params[uparam] or array_params[uparam] then
-				param_k, param_v = uparam, table.remove(arg, 1);
+				param_k = uparam;
+				param_v = param:match("^=(.*)$", #uparam+1);
 				if not param_v then
-					return nil, "missing-value", raw_param;
+					param_v = table.remove(arg, 1);
+					if not param_v then
+						return nil, "missing-value", raw_param;
+					end
 				end
 			else
 				param_k, param_v = param:match("^([^=]+)=(.+)$");