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src/librustc_codegen_ssa/back/link.rs

@@ -841,6 +841,12 @@ fn infer_from(
                     }
                     LinkerFlavor::Gcc => {
                         if cfg!(target_os = "solaris") {
+                            // On historical Solaris systems, "cc" may have
+                            // been Sun Studio, which is not flag-compatible
+                            // with "gcc".  This history casts a long shadow,
+                            // and many modern illumos distributions today
+                            // ship GCC as "gcc" without also making it
+                            // available as "cc".
                             "gcc"
                         } else {
                             "cc"