[analyzer] Turn missing tablegen doc entry of a checker into fatal error

[steakhal]

Summary

It turns out all checkers explicitly mention the Documentation<>.
It makes sense to demand this, so emit a fatal tablegen error if such
happens.

[Szelethus]

LGTM! You did check whether a missing doc field will actually trigger this error, right?

clang/utils/TableGen/ClangSACheckersEmitter.cpp

82

We might as well give an extra hand, and state that a Documentation<> field is missing.

[steakhal]

In D122244#3404727, @Szelethus wrote:

LGTM! You did check whether a missing doc field will actually trigger this error, right?

Yup, it works as expected!

ninja: Entering directory `build/release'
[1/375] Building Checkers.inc...
FAILED: tools/clang/include/clang/StaticAnalyzer/Checkers/Checkers.inc /git/llvm-project/build/release/tools/clang/include/clang/StaticAnalyzer/Checkers/Checkers.inc
cd /git/llvm-project/build/release && /git/llvm-project/build/release/bin/clang-tblgen -gen-clang-sa-checkers -I /git/llvm-project/clang/include/clang/StaticAnalyzer/Checkers -I/git/llvm-project/clang/include -I/git/llvm-project/build/release/tools/clang/include -I/git/llvm-project/build/release/include -I/git/llvm-project/llvm/include /git/llvm-project/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td --write-if-changed -o tools/clang/include/clang/StaticAnalyzer/Checkers/Checkers.inc -d tools/clang/include/clang/StaticAnalyzer/Checkers/Checkers.inc.d
/git/llvm-project/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td:585:1: error: missing Documentation for cplusplus.NewDelete
def NewDeleteChecker : Checker<"NewDelete">,
^
ninja: build stopped: subcommand failed.

clang/utils/TableGen/ClangSACheckersEmitter.cpp

82

Hmm, indeed.

[steakhal]

reword error message

[martong]

Good.

clang/utils/TableGen/ClangSACheckersEmitter.cpp

else
       PrintFatalError(R.getLoc(),
                       "missing Documentation for " + getCheckerFullName(&R));
   }
   return Value;
 }
 
 static std::string getCheckerDocs(const Record &R) {
   StringRef LandingPage;
-  if (BitsInit *BI = R.getValueAsBitsInit("Documentation")) {
-    uint64_t V = getValueFromBitsInit(BI, R);
-    if (V == 1)
-      LandingPage = "available_checks.html";
-    else if (V == 2)
-      LandingPage = "alpha_checks.html";
-  }
-  
+  const BitsInit *BI = R.getValueAsBitsInit("Documentation");
+  if (!BI)
+    PrintFatalError(R.getLoc(), "missing Documentation<...> member for " +
+                                    getCheckerFullName(&R));
+
   if (LandingPage.empty())
     return "";
 
   return (llvm::Twine("https://clang-analyzer.llvm.org/") + LandingPage + "#" +
           getCheckerFullName(&R))
       .str();
 }