[Swift version] Note all supported versions when -swift-version is misused.

Author: milseman

include/swift/AST/DiagnosticsFrontend.def

@@ -99,6 +99,8 @@ ERROR(error_no_source_location_scope_map,none,
 
 NOTE(note_swift_version_major, none,
      "use major version, as in '-swift-version %0'", (unsigned))
+NOTE(note_valid_swift_versions, none,
+     "valid arguments to '-swift-version' are %0", (StringRef))
 
 ERROR(error_mode_cannot_emit_dependencies,none,
   "this mode does not support emitting dependency files", ())

include/swift/Basic/Version.h

@@ -127,6 +127,12 @@ class Version {
   /// Returns a version from the currently defined SWIFT_VERSION_MAJOR and
   /// SWIFT_VERSION_MINOR.
   static Version getCurrentLanguageVersion();
+
+  // Whitelist of backward-compatibility versions that we permit passing as
+  // -swift-version <vers>
+  static std::array<StringRef, 2> getValidEffectiveVersions() {
+    return {{"3", "4"}};
+  };
 };
 
 bool operator>=(const Version &lhs, const Version &rhs);

lib/Basic/Version.cpp

@@ -310,17 +310,9 @@ Version::operator clang::VersionTuple() const
   }
 }
 
-bool
-Version::isValidEffectiveLanguageVersion() const
-{
-  // Whitelist of backward-compatibility versions that we permit passing as
-  // -swift-version <vers>
-  char const *whitelist[] = {
-    "3",
-    "4",
-  };
-  for (auto const i : whitelist) {
-    auto v = parseVersionString(i, SourceLoc(), nullptr);
+bool Version::isValidEffectiveLanguageVersion() const {
+  for (auto verStr : getValidEffectiveVersions()) {
+    auto v = parseVersionString(verStr, SourceLoc(), nullptr);
     assert(v.hasValue());
     if (v == *this)
       return true;

lib/Frontend/CompilerInvocation.cpp

@@ -761,6 +761,26 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   return false;
 }
 
+static void diagnoseSwiftVersion(Optional<version::Version> &vers, Arg *verArg,
+                                 ArgList &Args, DiagnosticEngine &diags) {
+  // General invalid version error
+  diags.diagnose(SourceLoc(), diag::error_invalid_arg_value,
+                 verArg->getAsString(Args), verArg->getValue());
+
+  // Check for an unneeded minor version, otherwise just list valid verions
+  if (vers.hasValue() && !vers.getValue().empty() &&
+      vers.getValue().asMajorVersion().isValidEffectiveLanguageVersion()) {
+    diags.diagnose(SourceLoc(), diag::note_swift_version_major,
+                   vers.getValue()[0]);
+  } else {
+    // Note valid versions instead
+    auto validVers = version::Version::getValidEffectiveVersions();
+    auto versStr =
+        "'" + llvm::join(validVers.begin(), validVers.end(), "', '") + "'";
+    diags.diagnose(SourceLoc(), diag::note_valid_swift_versions, versStr);
+  }
+}
+
 static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
                           DiagnosticEngine &Diags,
                           const FrontendOptions &FrontendOpts) {
@@ -773,16 +793,7 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
         vers.getValue().isValidEffectiveLanguageVersion()) {
       Opts.EffectiveLanguageVersion = vers.getValue();
     } else {
-      // General invalid version error
-      Diags.diagnose(SourceLoc(), diag::error_invalid_arg_value,
-                     A->getAsString(Args), A->getValue());
-
-      // Check for an unneeded minor version
-      if (vers.hasValue() && !vers.getValue().empty() &&
-          vers.getValue().asMajorVersion().isValidEffectiveLanguageVersion()) {
-        Diags.diagnose(SourceLoc(), diag::note_swift_version_major,
-                       vers.getValue()[0]);
-      }
+      diagnoseSwiftVersion(vers, A, Args, Diags);
     }
   }
 

test/Driver/swift-version.swift

@@ -1,4 +1,5 @@
 // RUN: %target-swiftc_driver -swift-version 3 %s
+// RUN: not %target-swiftc_driver -swift-version foo %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 1 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 2 %s 2>&1 | %FileCheck --check-prefix BAD %s
 // RUN: not %target-swiftc_driver -swift-version 2.3 %s 2>&1 | %FileCheck --check-prefix BAD %s
@@ -9,7 +10,9 @@
 // RUN: not %target-swiftc_driver -swift-version 4.3 %s 2>&1 | %FileCheck --check-prefix FIXIT_4 %s
 
 // BAD: invalid value
+// BAD: note: valid arguments to '-swift-version' are '3', '4'
+
 // FIXIT_3: use major version, as in '-swift-version 3'
-// FIXIT_4: use major version, as in '-swift-version 4
+// FIXIT_4: use major version, as in '-swift-version 4'
 
 let x = 1