[flang][OpenMP] Verify that N in -fopenmp-version=N is valid (#145725)

For historical versions that are unsupported, emit a warning and assume
the currently default version.
For values of N that are not integers or that don't correspond to any
OpenMP version (old or newer), emit an error.

1 files changed, 38 insertions, 4 deletions

diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 2603a3f..07d6814 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -26,6 +26,7 @@
 #include "clang/Driver/Driver.h"
 #include "clang/Driver/OptionUtils.h"
 #include "clang/Driver/Options.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Frontend/Debug/Options.h"
@@ -44,6 +45,7 @@
 #include <cstdlib>
 #include <memory>
 #include <optional>
+#include <sstream>
 
 using namespace Fortran::frontend;
 
@@ -1140,11 +1142,43 @@ static bool parseOpenMPArgs(CompilerInvocation &res, llvm::opt::ArgList &args,
   res.getLangOpts().OpenMPVersion = 31;
   res.getFrontendOpts().features.Enable(
       Fortran::common::LanguageFeature::OpenMP);
-  if (int Version = getLastArgIntValue(
-          args, clang::driver::options::OPT_fopenmp_version_EQ,
-          res.getLangOpts().OpenMPVersion, diags)) {
-    res.getLangOpts().OpenMPVersion = Version;
+  if (auto *arg =
+          args.getLastArg(clang::driver::options::OPT_fopenmp_version_EQ)) {
+    llvm::ArrayRef<unsigned> ompVersions = llvm::omp::getOpenMPVersions();
+    unsigned oldVersions[] = {11, 20, 25, 30};
+    unsigned version = 0;
+
+    auto reportBadVersion = [&](llvm::StringRef value) {
+      const unsigned diagID =
+          diags.getCustomDiagID(clang::DiagnosticsEngine::Error,
+                                "'%0' is not a valid OpenMP version in '%1', "
+                                "valid versions are %2");
+      std::string buffer;
+      llvm::raw_string_ostream versions(buffer);
+      llvm::interleaveComma(ompVersions, versions);
+
+      diags.Report(diagID) << value << arg->getAsString(args) << versions.str();
+    };
+
+    llvm::StringRef value = arg->getValue();
+    if (!value.getAsInteger(/*radix=*/10, version)) {
+      if (llvm::is_contained(ompVersions, version)) {
+        res.getLangOpts().OpenMPVersion = version;
+      } else if (llvm::is_contained(oldVersions, version)) {
+        const unsigned diagID =
+            diags.getCustomDiagID(clang::DiagnosticsEngine::Warning,
+                                  "OpenMP version %0 is no longer supported, "
+                                  "assuming version %1");
+        std::string assumed = std::to_string(res.getLangOpts().OpenMPVersion);
+        diags.Report(diagID) << value << assumed;
+      } else {
+        reportBadVersion(value);
+      }
+    } else {
+      reportBadVersion(value);
+    }
   }
+
   if (args.hasArg(clang::driver::options::OPT_fopenmp_force_usm)) {
     res.getLangOpts().OpenMPForceUSM = 1;
   }