[clang] [clang] [Gnu] Improve GCCVersion parsing to match versions such as "10-win32" (PR #69079)

[Jon Roelofs via cfe-commits]

================
@@ -2007,45 +2007,71 @@ Generic_GCC::GCCVersion Generic_GCC::GCCVersion::Parse(StringRef VersionText) {
   std::pair<StringRef, StringRef> First = VersionText.split('.');
   std::pair<StringRef, StringRef> Second = First.second.split('.');
 
-  GCCVersion GoodVersion = {VersionText.str(), -1, -1, -1, "", "", ""};
-  if (First.first.getAsInteger(10, GoodVersion.Major) || GoodVersion.Major < 0)
-    return BadVersion;
-  GoodVersion.MajorStr = First.first.str();
-  if (First.second.empty())
-    return GoodVersion;
+  StringRef MajorStr = First.first;
   StringRef MinorStr = Second.first;
-  if (Second.second.empty()) {
-    if (size_t EndNumber = MinorStr.find_first_not_of("0123456789")) {
-      GoodVersion.PatchSuffix = std::string(MinorStr.substr(EndNumber));
-      MinorStr = MinorStr.slice(0, EndNumber);
-    }
-  }
-  if (MinorStr.getAsInteger(10, GoodVersion.Minor) || GoodVersion.Minor < 0)
-    return BadVersion;
-  GoodVersion.MinorStr = MinorStr.str();
+  StringRef PatchStr = Second.second;
 
-  // First look for a number prefix and parse that if present. Otherwise just
-  // stash the entire patch string in the suffix, and leave the number
-  // unspecified. This covers versions strings such as:
-  //   5        (handled above)
+  GCCVersion GoodVersion = {VersionText.str(), -1, -1, -1, "", "", ""};
+
+  // Parse version number strings such as:
+  //   5
   //   4.4
   //   4.4-patched
   //   4.4.0
   //   4.4.x
   //   4.4.2-rc4
   //   4.4.x-patched
-  // And retains any patch number it finds.
-  StringRef PatchText = Second.second;
-  if (!PatchText.empty()) {
-    if (size_t EndNumber = PatchText.find_first_not_of("0123456789")) {
-      // Try to parse the number and any suffix.
-      if (PatchText.slice(0, EndNumber).getAsInteger(10, GoodVersion.Patch) ||
-          GoodVersion.Patch < 0)
-        return BadVersion;
-      GoodVersion.PatchSuffix = std::string(PatchText.substr(EndNumber));
+  //   10-win32
+  // Split on '.', handle 1, 2 or 3 such segments. Each segment must contain
+  // purely a number, except for the last one, where a non-number suffix
+  // is stored in PatchSuffix. The third segment is allowed to not contain
+  // a number at all.
+
+  auto HandleLastNumber = [&](StringRef Segment, int &Number,
+                              std::string &OutStr) -> bool {
+    // Look for a number prefix and parse that, and split out any trailing
+    // string into GoodVersion.PatchSuffix.
+
+    if (size_t EndNumber = Segment.find_first_not_of("0123456789")) {
+      StringRef NumberStr = Segment.slice(0, EndNumber);
+      if (NumberStr.getAsInteger(10, Number) || Number < 0)
+        return false;
+      OutStr = NumberStr;
+      GoodVersion.PatchSuffix = Segment.substr(EndNumber);
+      return true;
     }
+    return false;
+  };
+  auto HandleNumber = [](StringRef Segment, int &Number) -> bool {
+    if (Segment.getAsInteger(10, Number) || Number < 0)
+      return false;
+    return true;
+  };
+
+  if (MinorStr.empty()) {
+    // If no minor string, major is the last segment
+    if (!HandleLastNumber(MajorStr, GoodVersion.Major, GoodVersion.MajorStr))
+      return BadVersion;
+    return GoodVersion;
+  } else {
+    if (!HandleNumber(MajorStr, GoodVersion.Major))
+      return BadVersion;
+    GoodVersion.MajorStr = MajorStr;
+  }
+  if (PatchStr.empty()) {
+    // If no patch string, minor is the last segment
+    if (!HandleLastNumber(MinorStr, GoodVersion.Minor, GoodVersion.MinorStr))
+      return BadVersion;
+    return GoodVersion;
+  } else {
+    if (!HandleNumber(MinorStr, GoodVersion.Minor))
+      return BadVersion;
+    GoodVersion.MinorStr = MinorStr;
   }
 
+  // For the last segment, tolerate a missing number.
+  std::string DummyStr;
+  HandleLastNumber(PatchStr, GoodVersion.Patch, DummyStr);
----------------
jroelofs wrote:

What if the segment after the `-` is only a number e.g. `10-10`? If I'm reading this correctly, think in that case we end up leaving that out of the PatchSuffix.

Looks like https://semver.org/ allows this case in the grammar, though I'm not sure if GCC versions strictly adhere to that standard.

https://github.com/llvm/llvm-project/pull/69079