[clang] [clang] Fix false positive with -Wdocumentation and explicit instanti… (PR #178223)

[Carlos Galvez via cfe-commits]

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@@ -854,6 +868,19 @@ bool Sema::isTemplateOrSpecialization() {
   return ThisDeclInfo->getTemplateKind() != DeclInfo::NotTemplate;
 }
 
+bool Sema::isExplicitInstantiation() {
+  if (!ThisDeclInfo)
+    return false;
+  if (!ThisDeclInfo->IsFilled)
+    inspectThisDecl();
+  if (const auto *FD = dyn_cast<FunctionDecl>(ThisDeclInfo->CurrentDecl)) {
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carlosgalvezp wrote:

Made it more _explicit_, let me know if it's enough! :) 

https://github.com/llvm/llvm-project/pull/178223