[llvm] [CommandLine] Better report unknown subcommands (PR #74811)

[James Henderson via llvm-commits]

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@@ -2206,4 +2206,25 @@ TEST(CommandLineTest, DefaultValue) {
   EXPECT_EQ(1, StrInitOption.getNumOccurrences());
 }
 
+TEST(CommandLineTest, UnknownSubcommand) {
+  cl::ResetCommandLineParser();
+
+  StackSubCommand SC1("foo", "Foo subcommand");
+  StackSubCommand SC2("bar", "Bar subcommand");
+  StackOption<bool> SC1Opt("f", cl::sub(SC1));
+  StackOption<bool> SC2Opt("b", cl::sub(SC2));
+  StackOption<bool> TopOpt("t");
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jh7370 wrote:

Perhaps worth adding a second top-level option to show that the right one is picked for the suggestion here too.

https://github.com/llvm/llvm-project/pull/74811