cmArgumentParser: Capture keyword errors in parse results

Since commit f46b2e9142 (cmArgumentParser: Model maybe-missing string
with wrapper type, 2022-07-06) we know during parsing whether or not it
is an error for a keyword to be missing a value.  Record such errors in
the parse results structure.  Offer clients a helper method to report
them.  This provides clients with an alternative to manually checking
`keywordsMissingValue` and generating their own error message.

2 files changed, 39 insertions, 1 deletions

diff --git a/Source/cmArgumentParser.cxx b/Source/cmArgumentParser.cxx
index c997933..25d5c68 100644
--- a/Source/cmArgumentParser.cxx
+++ b/Source/cmArgumentParser.cxx
@@ -5,6 +5,9 @@
 #include <algorithm>
 
 #include "cmArgumentParserTypes.h"
+#include "cmMakefile.h"
+#include "cmMessageType.h"
+#include "cmStringAlgorithms.h"
 
 namespace ArgumentParser {
 
@@ -106,10 +109,27 @@ void Instance::FinishKeyword()
     return;
   }
   if (this->ExpectValue) {
+    if (this->ParseResults != nullptr) {
+      this->ParseResults->AddKeywordError(this->Keyword,
+                                          "  missing required value\n");
+    }
     if (this->KeywordsMissingValue != nullptr) {
       this->KeywordsMissingValue->emplace_back(this->Keyword);
     }
   }
 }
 
+bool ParseResult::MaybeReportError(cmMakefile& mf) const
+{
+  if (*this) {
+    return false;
+  }
+  std::string e;
+  for (auto const& ke : this->KeywordErrors) {
+    e = cmStrCat(e, "Error after keyword \"", ke.first, "\":\n", ke.second);
+  }
+  mf.IssueMessage(MessageType::FATAL_ERROR, e);
+  return true;
+}
+
 } // namespace ArgumentParser
diff --git a/Source/cmArgumentParser.h b/Source/cmArgumentParser.h
index 0078c04..8fda8b7 100644
--- a/Source/cmArgumentParser.h
+++ b/Source/cmArgumentParser.h
@@ -6,6 +6,7 @@
 
 #include <cassert>
 #include <functional>
+#include <map>
 #include <string>
 #include <utility>
 #include <vector>
@@ -20,12 +21,29 @@
 template <typename Result>
 class cmArgumentParser; // IWYU pragma: keep
 
+class cmMakefile;
+
 namespace ArgumentParser {
 
 class ParseResult
 {
+  std::map<cm::string_view, std::string> KeywordErrors;
+
 public:
-  explicit operator bool() const { return true; }
+  explicit operator bool() const { return this->KeywordErrors.empty(); }
+
+  void AddKeywordError(cm::string_view key, cm::string_view text)
+
+  {
+    this->KeywordErrors[key] += text;
+  }
+
+  std::map<cm::string_view, std::string> const& GetKeywordErrors() const
+  {
+    return this->KeywordErrors;
+  }
+
+  bool MaybeReportError(cmMakefile& mf) const;
 };
 
 template <typename Result>