[clang] [clang][modules-driver] Add scanner to detect C++20 module presence (PR #145220)

[Chuanqi Xu via cfe-commits]

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@@ -790,6 +792,35 @@ class Driver {
   /// compilation based on which -f(no-)?lto(=.*)? option occurs last.
   void setLTOMode(const llvm::opt::ArgList &Args);
 
+  /// BuildDefaultActions - Constructs the list of actions to perform
+  /// for the provided arguments, which are only done for a single architecture.
+  ///
+  /// \param C - The compilation that is being built.
+  /// \param Args - The input arguments.
+  /// \param Actions - The list to store the resulting actions onto.
+  void BuildDefaultActions(Compilation &C, llvm::opt::DerivedArgList &Args,
+                           const InputList &Inputs, ActionList &Actions) const;
+
+  /// BuildExplicitModuleBuildActions - Performs a dependency scan and
+  /// constructs the list of actions to perform for dependency order and
+  /// the provided arguments. This is only done for a single a architecture.
+  ///
+  /// \param C - The compilation that is being built.
+  /// \param Args - The input arguments.
+  /// \param Actions - The list to store the resulting actions onto.
+  void BuildExplicitModuleBuildActions(Compilation &C,
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ChuanqiXu9 wrote:

ditto, please change the name `explicit module`.

https://github.com/llvm/llvm-project/pull/145220