From 0e1b73e3b43bca7c1d77ed669b364819ad211da9 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 2 Feb 2024 11:41:33 +0200
Subject: Handle unseparated `rc` and `git` suffixes in Clang version (GH issue
 #360)

---
 libbuild2/cc/guess.cxx | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/libbuild2/cc/guess.cxx b/libbuild2/cc/guess.cxx
index 48240d4..d7e9c63 100644
--- a/libbuild2/cc/guess.cxx
+++ b/libbuild2/cc/guess.cxx
@@ -2424,6 +2424,12 @@ namespace build2
       //
       // emcc (...) 2.0.8
       //
+      // Pre-releases of the vanilla Clang append `rc` or `git` to the
+      // version, unfortunately without a separator. So we will handle these
+      // ad hoc. For example:
+      //
+      // FreeBSD clang version 18.1.0rc (https://github.com/llvm/llvm-project.git llvmorg-18-init-18361-g22683463740e)
+      //
       auto extract_version = [] (const string& s, bool patch, const char* what)
         -> compiler_version
       {
@@ -2438,8 +2444,28 @@ namespace build2
           // end of the word position (first space). In fact, we can just
           // check if it is >= e.
           //
-          if (s.find_first_not_of ("1234567890.", b, 11) >= e)
+          size_t p (s.find_first_not_of ("1234567890.", b, 11));
+          if (p >= e)
             break;
+
+          // Handle the unseparated `rc` and `git` suffixes.
+          //
+          if (p != string::npos)
+          {
+            if (p + 2 == e && (e - b) > 2 &&
+                s[p] == 'r' && s[p + 1] == 'c')
+            {
+              e -= 2;
+              break;
+            }
+
+            if (p + 3 == e && (e - b) > 3 &&
+                s[p] == 'g' && s[p + 1] == 'i' && s[p + 2] == 't')
+            {
+              e -= 3;
+              break;
+            }
+          }
         }
 
         if (b == e)
@@ -2475,7 +2501,14 @@ namespace build2
         ver.patch = next ("patch", patch);
 
         if (e != s.size ())
-          ver.build.assign (s, e + 1, string::npos);
+        {
+          // Skip the separator (it could also be unseparated `rc` or `git`).
+          //
+          if (s[e] == ' ' || s[e] == '-')
+            e++;
+
+          ver.build.assign (s, e, string::npos);
+        }
 
         return ver;
       };
@@ -2499,7 +2532,10 @@ namespace build2
 
         // Some overrides for testing.
         //
+        //string s (xv != nullptr ? *xv : "");
+        //
         //s = "clang version 3.7.0 (tags/RELEASE_370/final)";
+        //s = "FreeBSD clang version 18.1.0rc (https://github.com/llvm/llvm-project.git llvmorg-18-init-18361-g22683463740e)";
         //
         //gr.id.variant = "apple";
         //s = "Apple LLVM version 7.3.0 (clang-703.0.16.1)";
-- 
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