for Solaris, part from upstream commit
https://github.com/boostorg/process/commit/bb375f50bd5b362b087aab326df158a440882e29

--- boost_1_87_0/libs/process/src/ext/cwd.cpp
+++ boost_1_87_0/libs/process/src/ext/cwd.cpp
@@ -124,7 +124,7 @@
             filesystem::path("/proc") / std::to_string(pid) / "cwd", ec
             );
 #elif defined(__sun)
-    return fileystem::canonical(
+    return filesystem::canonical(
             filesystem::path("/proc") / std::to_string(pid) / "path/cwd", ec
             );
 #endif
--- boost_1_87_0/libs/process/src/ext/exe.cpp
+++ boost_1_87_0/libs/process/src/ext/exe.cpp
@@ -138,7 +138,7 @@
             filesystem::path("/proc") / std::to_string(pid) / "exe", ec
             );
 #elif defined(__sun)
-    return fileystem::canonical(
+    return filesystem::canonical(
             filesystem::path("/proc") / std::to_string(pid) / "path/a.out", ec
             );
 #endif