[flang-commits] [flang] [Flang][#212316] Fix -Wunused-template errors under -Werror (PR #218985)

[via flang-commits]

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@@ -15,8 +15,7 @@ namespace Fortran::evaluate {
 
 // DOT_PRODUCT
 template <typename T>
-static Expr<T> FoldDotProduct(
-    FoldingContext &context, FunctionRef<T> &&funcRef) {
+Expr<T> FoldDotProduct(FoldingContext &context, FunctionRef<T> &&funcRef) {
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zhangweize9-cyber wrote:

(Assisted-by: Google AI Mode) If this header file is included by two or more .cpp files (Translation Units) using `#include`, when they are compiled into .o object files and handed over to the linker for packaging, the linker will directly report an error and crash. 

```
ld: error: duplicate symbol: FoldDotProduct(...)
    defined in file_A.o
    defined in file_B.o
```

(solution) [Here's the stackoverflow link.](https://stackoverflow.com/questions/68186806/why-does-defining-functions-in-header-files-create-multiple-definition-errors-b) If the `inline` keyword is not added, it will occur during the linking process. Because there are multiple definitions.

https://github.com/llvm/llvm-project/pull/218985