cmSubcommandTable: Implement closest string for invalid subcommand

.codespellrc

@@ -17,6 +17,7 @@ skip =
   Source/kwsys/*,
   Tests/RunCMake/CPack/tests/DMG_SLA/German.*,
   Tests/RunCMake/CommandLine/RunCMakeTest.cmake,
+  Tests/RunCMake/list/InvalidSubcommandDidYouMean*,
   Tests/RunCMake/ParseImplicitData/*.input,
   Tests/RunCMake/cmake_language/call_typo_function.cmake,
   Tests/StringFileTest/test.utf8,

Source/cmSubcommandTable.cxx

@@ -26,6 +26,17 @@ bool cmSubcommandTable::operator()(cm::string_view key,
   if (it != this->Impl.end() && it->first == key) {
     return it->second(args, status);
   }
-  status.SetError(cmStrCat("does not recognize sub-command ", key));
+  std::string error = cmStrCat("does not recognize sub-command ", key);
+  std::vector<std::string> candidates;
+  candidates.reserve(this->Impl.size());
+  for (Elem const& elem : this->Impl) {
+    candidates.emplace_back(elem.first);
+  }
+  std::string const suggestion = cmFindClosestString(key, candidates);
+  if (!suggestion.empty()) {
+    error =
+      cmStrCat(std::move(error), ". Did you mean: \"", suggestion, "\"?");
+  }
+  status.SetError(error);
   return false;
 }

Tests/RunCMake/list/InvalidSubcommandDidYouMean-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/list/InvalidSubcommandDidYouMean-stderr.txt

@@ -0,0 +1,4 @@
+^CMake Error at InvalidSubcommandDidYouMean\.cmake:1 \(list\):
+  list does not recognize sub-command APEND\.  Did you mean: "APPEND"\?
+Call Stack \(most recent call first\):
+  CMakeLists\.txt:3 \(include\)$

Tests/RunCMake/list/InvalidSubcommandDidYouMean.cmake

@@ -0,0 +1 @@
+list(APEND mylist a)

Tests/RunCMake/list/RunCMakeTest.cmake

@@ -7,6 +7,7 @@ run_cmake(EmptyInsert-1)
 
 run_cmake(NoArguments)
 run_cmake(InvalidSubcommand)
+run_cmake(InvalidSubcommandDidYouMean)
 
 run_cmake(FILTER-REGEX-InvalidRegex)
 run_cmake(GET-InvalidIndex)