[lld] [lld][elf] Warn if '*' pattern is used multiple times in version scripts (PR #102669)

[Fangrui Song via llvm-commits]

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@@ -311,13 +311,44 @@ void SymbolTable::scanVersionScript() {
 
   // Then, assign versions to "*". In GNU linkers they have lower priority than
   // other wildcards.
+  bool globalAsteriskWildcardFound = false;
+  bool localAsteriskWildcardFound = false;
+  bool asteriskWildcardReported = false;
+  auto assignAsteriskWildcard = [&](SymbolVersion &pat, VersionDefinition *ver,
+                                    bool isLocal) {
+    // Avoid issuing a warning if both '--retain-symbol-file' and a version
+    // script with `global: *` are used.
+    //
+    // '--retain-symbol-file' adds a "*" pattern to
+    // 'config->versionDefinitions[VER_NDX_LOCAL].nonLocalPatterns', see
+    // 'readConfigs()' in 'Driver.cpp'. Note that it is '.nonLocalPatterns', not
+    // '.localPatterns', which may seem counterintuitive, but still works as
+    // expected. Here we can exploit that and skip analyzing the pattern added
+    // for this option.
+    if (!asteriskWildcardReported && (isLocal || ver->id > VER_NDX_LOCAL)) {
+      if ((isLocal && globalAsteriskWildcardFound) ||
+          (!isLocal && localAsteriskWildcardFound)) {
+        warn("Wildcard pattern '*' is used for both 'local' and 'global' "
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MaskRay wrote:

We don't capitalize warn/error messages 

https://github.com/llvm/llvm-project/pull/102669