[PATCH] D90646: [clang] Add warning when `-include-pch` is passed multiple times

[Keith Smiley via Phabricator via cfe-commits]

keith created this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
keith requested review of this revision.

Previously this argument passed multiple times would result in the first
being silently ignored.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90646

Files:
  clang/include/clang/Basic/DiagnosticDriverKinds.td
  clang/lib/Frontend/CompilerInvocation.cpp
  clang/test/PCH/multiple-include-pch-warning.c


Index: clang/test/PCH/multiple-include-pch-warning.c
===================================================================
--- /dev/null
+++ clang/test/PCH/multiple-include-pch-warning.c
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -emit-pch -o %t1.pch %s
+// RUN: %clang_cc1 -emit-pch -o %t2.pch %s
+// RUN: %clang_cc1 %s -include-pch %t1.pch -include-pch %t2.pch 2>&1 | FileCheck %s
+
+// CHECK: warning: -include-pch passed multiple times but only the last '{{.*\.pch}}' is being used
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -3576,7 +3576,13 @@
 static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
                                   DiagnosticsEngine &Diags,
                                   frontend::ActionKind Action) {
-  Opts.ImplicitPCHInclude = std::string(Args.getLastArgValue(OPT_include_pch));
+  auto allPchFiles = Args.getAllArgValues(OPT_include_pch);
+  if (!allPchFiles.empty()) {
+    Opts.ImplicitPCHInclude = std::string(allPchFiles.back());
+    if (allPchFiles.size() > 1)
+      Diags.Report(diag::warn_drv_multiple_include_pch)
+          << Opts.ImplicitPCHInclude;
+  }
   Opts.PCHWithHdrStop = Args.hasArg(OPT_pch_through_hdrstop_create) ||
                         Args.hasArg(OPT_pch_through_hdrstop_use);
   Opts.PCHWithHdrStopCreate = Args.hasArg(OPT_pch_through_hdrstop_create);
Index: clang/include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -329,6 +329,8 @@
   InGroup<Deprecated>;
 def warn_drv_pch_not_first_include : Warning<
   "precompiled header '%0' was ignored because '%1' is not first '-include'">;
+def warn_drv_multiple_include_pch : Warning<
+  "-include-pch passed multiple times but only the last '%0' is being used">;
 def warn_missing_sysroot : Warning<"no such sysroot directory: '%0'">,
   InGroup<DiagGroup<"missing-sysroot">>;
 def warn_incompatible_sysroot : Warning<"using sysroot for '%0' but targeting '%1'">,


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