[clang/DiagnosticLexKinds] Mark -Wreproducible-caching as DefaultWarnNoWerror/ShowInSystemHeader/ShowInSystemMacro

This allows the warning to be visible during a caching invocation by default, without getting affected by -Werror.

(cherry picked from commit f31ea45)

Author: akyrtzi

clang/include/clang/Basic/DiagnosticLexKinds.td

@@ -764,7 +764,8 @@ def warn_pp_date_time : Warning<
 
 def warn_pp_encounter_nonreproducible: Warning<
   "encountered non-reproducible token, caching will be skipped">,
-  InGroup<DiagGroup<"reproducible-caching">>, DefaultIgnore;
+  InGroup<DiagGroup<"reproducible-caching">>,
+  DefaultWarnNoWerror, ShowInSystemHeader, ShowInSystemMacro;
 def err_pp_encounter_nonreproducible: Error<
   "encountered non-reproducible token, caching failed">;
 

clang/test/CAS/warn-reproducible-caching.c

@@ -0,0 +1,24 @@
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: split-file %s %t
+
+// No warning in normal invocation.
+// RUN: %clang -target x86_64-apple-macos11 -fsyntax-only %t/t.c -isystem %t/sys 2>&1 | FileCheck %s --check-prefix=NOWARN --allow-empty
+// NOWARN-NOT: warning
+
+// Warning in cached invocation even if coming from system header. -Werror does not affect it.
+// RUN: %clang -target x86_64-apple-macos11 -c %t/t.c -o %t/t.o -isystem %t/sys -Werror \
+// RUN:   -fdepscan=inline -Xclang -fcas-path -Xclang %t/cas -Xclang -fcache-compile-job 2>&1 | FileCheck %s --check-prefix=WARN
+// WARN: warning: encountered non-reproducible token
+
+// Error if explicitly turned into error.
+// RUN: not %clang -target x86_64-apple-macos11 -c %t/t.c -o %t/t.o -isystem %t/sys -Werror=reproducible-caching \
+// RUN:   -fdepscan=inline -Xclang -fcas-path -Xclang %t/cas -Xclang -fcache-compile-job 2>&1 | FileCheck %s --check-prefix=ERROR
+// ERROR: error: encountered non-reproducible token
+
+//--- t.c
+#include <sys.h>
+
+//--- sys/sys.h
+const char *foo() {
+  return __DATE__;
+}