[NFC][clang] Move argument handling: Driver::BuildActions -> handleArguments (llvm#142455)

This simply moves code for diagnosing misuse of arguments `/Fo`, `/Fa`,
and `/o` from `Driver::BuildActions` into `Driver::handleArguments`,
following the intention of 740f69b.
This change better aligns with the roles of `BuildActions` and
`handleArguments`.

Author: naveen-seth

clang/lib/Driver/Driver.cpp

@@ -4226,6 +4226,39 @@ void Driver::handleArguments(Compilation &C, DerivedArgList &Args,
                              const InputList &Inputs,
                              ActionList &Actions) const {
 
+  // Diagnose misuse of /Fo.
+  if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fo)) {
+    StringRef V = A->getValue();
+    if (Inputs.size() > 1 && !V.empty() &&
+        !llvm::sys::path::is_separator(V.back())) {
+      // Check whether /Fo tries to name an output file for multiple inputs.
+      Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
+          << A->getSpelling() << V;
+      Args.eraseArg(options::OPT__SLASH_Fo);
+    }
+  }
+
+  // Diagnose misuse of /Fa.
+  if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fa)) {
+    StringRef V = A->getValue();
+    if (Inputs.size() > 1 && !V.empty() &&
+        !llvm::sys::path::is_separator(V.back())) {
+      // Check whether /Fa tries to name an asm file for multiple inputs.
+      Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
+          << A->getSpelling() << V;
+      Args.eraseArg(options::OPT__SLASH_Fa);
+    }
+  }
+
+  // Diagnose misuse of /o.
+  if (Arg *A = Args.getLastArg(options::OPT__SLASH_o)) {
+    if (A->getValue()[0] == '\0') {
+      // It has to have a value.
+      Diag(clang::diag::err_drv_missing_argument) << A->getSpelling() << 1;
+      Args.eraseArg(options::OPT__SLASH_o);
+    }
+  }
+
   // Ignore /Yc/Yu if both /Yc and /Yu passed but with different filenames.
   Arg *YcArg = Args.getLastArg(options::OPT__SLASH_Yc);
   Arg *YuArg = Args.getLastArg(options::OPT__SLASH_Yu);
@@ -4368,39 +4401,6 @@ void Driver::BuildActions(Compilation &C, DerivedArgList &Args,
     return;
   }
 
-  // Diagnose misuse of /Fo.
-  if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fo)) {
-    StringRef V = A->getValue();
-    if (Inputs.size() > 1 && !V.empty() &&
-        !llvm::sys::path::is_separator(V.back())) {
-      // Check whether /Fo tries to name an output file for multiple inputs.
-      Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
-          << A->getSpelling() << V;
-      Args.eraseArg(options::OPT__SLASH_Fo);
-    }
-  }
-
-  // Diagnose misuse of /Fa.
-  if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fa)) {
-    StringRef V = A->getValue();
-    if (Inputs.size() > 1 && !V.empty() &&
-        !llvm::sys::path::is_separator(V.back())) {
-      // Check whether /Fa tries to name an asm file for multiple inputs.
-      Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
-          << A->getSpelling() << V;
-      Args.eraseArg(options::OPT__SLASH_Fa);
-    }
-  }
-
-  // Diagnose misuse of /o.
-  if (Arg *A = Args.getLastArg(options::OPT__SLASH_o)) {
-    if (A->getValue()[0] == '\0') {
-      // It has to have a value.
-      Diag(clang::diag::err_drv_missing_argument) << A->getSpelling() << 1;
-      Args.eraseArg(options::OPT__SLASH_o);
-    }
-  }
-
   handleArguments(C, Args, Inputs, Actions);
 
   bool UseNewOffloadingDriver =