VS: Generalize CSharp /langversion flag mapping

Map the `/langversion:` flag followed by any value to a `LangVersion`
element with the specified value in the `.csproj` file.

Fixes: #22089

6 files changed, 36 insertions, 270 deletions

diff --git a/Templates/MSBuild/FlagTables/v10_CSharp.json b/Templates/MSBuild/FlagTables/v10_CSharp.json
index 5989aea1ec..9f21d9a27b 100644
--- a/Templates/MSBuild/FlagTables/v10_CSharp.json
+++ b/Templates/MSBuild/FlagTables/v10_CSharp.json
@@ -363,52 +363,13 @@
   },
   {
     "name":  "LangVersion",
-    "switch": "langversion:ISO-1",
+    "switch": "langversion:",
     "comment": "",
-    "value": "ISO-1",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:ISO-2",
-    "comment": "",
-    "value": "ISO-2",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:3",
-    "comment": "",
-    "value": "3",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:4",
-    "comment": "",
-    "value": "4",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:5",
-    "comment": "",
-    "value": "5",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:6",
-    "comment": "",
-    "value": "6",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:default",
-    "comment": "",
-    "value": "default",
-    "flags": []
+    "value": "",
+    "flags": [
+      "UserValue",
+      "UserRequired"
+    ]
   },
   {
     "name":  "DelaySign",
diff --git a/Templates/MSBuild/FlagTables/v11_CSharp.json b/Templates/MSBuild/FlagTables/v11_CSharp.json
index 5989aea1ec..9f21d9a27b 100644
--- a/Templates/MSBuild/FlagTables/v11_CSharp.json
+++ b/Templates/MSBuild/FlagTables/v11_CSharp.json
@@ -363,52 +363,13 @@
   },
   {
     "name":  "LangVersion",
-    "switch": "langversion:ISO-1",
+    "switch": "langversion:",
     "comment": "",
-    "value": "ISO-1",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:ISO-2",
-    "comment": "",
-    "value": "ISO-2",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:3",
-    "comment": "",
-    "value": "3",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:4",
-    "comment": "",
-    "value": "4",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:5",
-    "comment": "",
-    "value": "5",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:6",
-    "comment": "",
-    "value": "6",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:default",
-    "comment": "",
-    "value": "default",
-    "flags": []
+    "value": "",
+    "flags": [
+      "UserValue",
+      "UserRequired"
+    ]
   },
   {
     "name":  "DelaySign",
diff --git a/Templates/MSBuild/FlagTables/v12_CSharp.json b/Templates/MSBuild/FlagTables/v12_CSharp.json
index 5989aea1ec..9f21d9a27b 100644
--- a/Templates/MSBuild/FlagTables/v12_CSharp.json
+++ b/Templates/MSBuild/FlagTables/v12_CSharp.json
@@ -363,52 +363,13 @@
   },
   {
     "name":  "LangVersion",
-    "switch": "langversion:ISO-1",
+    "switch": "langversion:",
     "comment": "",
-    "value": "ISO-1",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:ISO-2",
-    "comment": "",
-    "value": "ISO-2",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:3",
-    "comment": "",
-    "value": "3",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:4",
-    "comment": "",
-    "value": "4",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:5",
-    "comment": "",
-    "value": "5",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:6",
-    "comment": "",
-    "value": "6",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:default",
-    "comment": "",
-    "value": "default",
-    "flags": []
+    "value": "",
+    "flags": [
+      "UserValue",
+      "UserRequired"
+    ]
   },
   {
     "name":  "DelaySign",
diff --git a/Templates/MSBuild/FlagTables/v140_CSharp.json b/Templates/MSBuild/FlagTables/v140_CSharp.json
index 5989aea1ec..9f21d9a27b 100644
--- a/Templates/MSBuild/FlagTables/v140_CSharp.json
+++ b/Templates/MSBuild/FlagTables/v140_CSharp.json
@@ -363,52 +363,13 @@
   },
   {
     "name":  "LangVersion",
-    "switch": "langversion:ISO-1",
+    "switch": "langversion:",
     "comment": "",
-    "value": "ISO-1",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:ISO-2",
-    "comment": "",
-    "value": "ISO-2",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:3",
-    "comment": "",
-    "value": "3",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:4",
-    "comment": "",
-    "value": "4",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:5",
-    "comment": "",
-    "value": "5",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:6",
-    "comment": "",
-    "value": "6",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:default",
-    "comment": "",
-    "value": "default",
-    "flags": []
+    "value": "",
+    "flags": [
+      "UserValue",
+      "UserRequired"
+    ]
   },
   {
     "name":  "DelaySign",
diff --git a/Templates/MSBuild/FlagTables/v141_CSharp.json b/Templates/MSBuild/FlagTables/v141_CSharp.json
index 5989aea1ec..9f21d9a27b 100644
--- a/Templates/MSBuild/FlagTables/v141_CSharp.json
+++ b/Templates/MSBuild/FlagTables/v141_CSharp.json
@@ -363,52 +363,13 @@
   },
   {
     "name":  "LangVersion",
-    "switch": "langversion:ISO-1",
+    "switch": "langversion:",
     "comment": "",
-    "value": "ISO-1",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:ISO-2",
-    "comment": "",
-    "value": "ISO-2",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:3",
-    "comment": "",
-    "value": "3",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:4",
-    "comment": "",
-    "value": "4",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:5",
-    "comment": "",
-    "value": "5",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:6",
-    "comment": "",
-    "value": "6",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:default",
-    "comment": "",
-    "value": "default",
-    "flags": []
+    "value": "",
+    "flags": [
+      "UserValue",
+      "UserRequired"
+    ]
   },
   {
     "name":  "DelaySign",
diff --git a/Templates/MSBuild/FlagTables/v142_CSharp.json b/Templates/MSBuild/FlagTables/v142_CSharp.json
index 4dcea9de32..ae1bd47bf6 100644
--- a/Templates/MSBuild/FlagTables/v142_CSharp.json
+++ b/Templates/MSBuild/FlagTables/v142_CSharp.json
@@ -381,52 +381,13 @@
   },
   {
     "name":  "LangVersion",
-    "switch": "langversion:ISO-1",
+    "switch": "langversion:",
     "comment": "",
-    "value": "ISO-1",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:ISO-2",
-    "comment": "",
-    "value": "ISO-2",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:3",
-    "comment": "",
-    "value": "3",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:4",
-    "comment": "",
-    "value": "4",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:5",
-    "comment": "",
-    "value": "5",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:6",
-    "comment": "",
-    "value": "6",
-    "flags": []
-  },
-  {
-    "name":  "LangVersion",
-    "switch": "langversion:default",
-    "comment": "",
-    "value": "default",
-    "flags": []
+    "value": "",
+    "flags": [
+      "UserValue",
+      "UserRequired"
+    ]
   },
   {
     "name":  "DelaySign",