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

[Karl-Johan Karlsson via llvm-commits]

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@@ -309,13 +309,43 @@ void SymbolTable::scanVersionScript() {
 
   // Then, assign versions to "*". In GNU linkers they have lower priority than
   // other wildcards.
+  bool globalAsteriskFound = false;
+  bool localAsteriskFound = false;
+  bool asteriskReported = false;
+  auto assignAsterisk = [&](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 not '.localPatterns',
+    // and may seem counterintuitive, but still works as expected. Here we can
+    // exploit that and skip analyzing the pattern added for this option.
+    if (!asteriskReported && (isLocal || ver->id > VER_NDX_LOCAL)) {
+      if ((isLocal && globalAsteriskFound) ||
+          (!isLocal && localAsteriskFound)) {
+        warn("wildcard pattern '*' is used for both 'local' and 'global' "
+             "scopes in version script");
+        asteriskReported = true;
+      } else if (!isLocal && globalAsteriskFound) {
+        warn("wildcard pattern '*' is used for multiple version definitions in "
+             "version script");
+        asteriskReported = true;
+      } else {
+        localAsteriskFound = isLocal;
+        globalAsteriskFound = !isLocal;
+      }
+    }
+    assignWildcard(pat, isLocal ? VER_NDX_LOCAL : ver->id, ver->name);
----------------
karka228 wrote:

Hi! I get this gcc warning from this code:
```
  lld/ELF/SymbolTable.cpp:340:33: warning: enumeral and non-enumeral type in conditional expression [-Wextra]
  340 |     assignWildcard(pat, isLocal ? VER_NDX_LOCAL : ver->id, ver->name);
      |                         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
```
Could a cast to uint16_t of VER_NDX_LOCAL be added to avoid the warning? Like this:
```
    assignWildcard(pat, isLocal ? (uint16_t)VER_NDX_LOCAL : ver->id, ver->name);
```


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