[Driver] When forcing a crash print the bug report message

Commit a945037e8f moved the printing of the
"PLEASE submit a bug report" message to the crash handler, but that means we
don't print it when forcing a crash using FORCE_CLANG_DIAGNOSTICS_CRASH. Fix
this by adding a function to get the bug report message and printing it when
forcing a crash.

Differential Revision: https://reviews.llvm.org/D81672

clang/test/Driver/crash-report-crashfile.m

@@ -18,6 +18,7 @@
 const int x = MODULE_MACRO;
 
 // CRASH_ENV: failing because environment variable 'FORCE_CLANG_DIAGNOSTICS_CRASH' is set
+// CRASH_ENV: PLEASE submit a bug report to {{.*}} and include the crash backtrace, preprocessed source, and associated run script.
 // CRASH_ENV: Preprocessed source(s) and associated run script(s) are located at:
 // CRASH_ENV-NEXT: note: diagnostic msg: {{.*}}.m
 // CRASH_ENV-NEXT: note: diagnostic msg: {{.*}}.cache

clang/test/Driver/crash-report-modules.m

@@ -19,6 +19,7 @@
 @import simple;
 const int x = MODULE_MACRO;
 
+// CHECK: PLEASE submit a bug report to {{.*}} and include the crash backtrace, preprocessed source, and associated run script.
 // CHECK: Preprocessed source(s) and associated run script(s) are located at:
 // CHECK-NEXT: note: diagnostic msg: {{.*}}.m
 // CHECK-NEXT: note: diagnostic msg: {{.*}}.cache

clang/test/Driver/crash-report-null.test

@@ -3,5 +3,6 @@
 // FIXME: Investigating. "fatal error: file 'nul' modified since it was first processed"
 // XFAIL: windows-gnu
 
+// CHECK: PLEASE submit a bug report to {{.*}} and include the crash backtrace, preprocessed source, and associated run script.
 // CHECK: Preprocessed source(s) and associated run script(s) are located at:
 // CHECK-NEXT: note: diagnostic msg: {{.*}}null-{{.*}}.c

clang/tools/driver/driver.cpp

@@ -511,6 +511,11 @@ int main(int argc_, const char **argv_) {
       for (const auto &J : C->getJobs())
         if (const Command *C = dyn_cast<Command>(&J))
           FailingCommands.push_back(std::make_pair(-1, C));
+
+      // Print the bug report message that would be printed if we did actually
+      // crash, but only if we're crashing due to FORCE_CLANG_DIAGNOSTICS_CRASH.
+      if (::getenv("FORCE_CLANG_DIAGNOSTICS_CRASH"))
+        llvm::dbgs() << llvm::getBugReportMsg();
     }
 
     for (const auto &P : FailingCommands) {

llvm/include/llvm/Support/PrettyStackTrace.h

@@ -41,6 +41,9 @@ namespace llvm {
   /// a crash.
   void setBugReportMsg(const char *Msg);
 
+  /// Get the bug report message that will be output upon a crash.
+  const char *getBugReportMsg();
+
   /// PrettyStackTraceEntry - This class is used to represent a frame of the
   /// "pretty" stack trace that is dumped when a program crashes. You can define
   /// subclasses of this and declare them on the program stack: when they are

llvm/lib/Support/PrettyStackTrace.cpp

@@ -33,6 +33,10 @@
 
 using namespace llvm;
 
+static const char *BugReportMsg =
+    "PLEASE submit a bug report to " BUG_REPORT_URL
+    " and include the crash backtrace.\n";
+
 // If backtrace support is not enabled, compile out support for pretty stack
 // traces.  This has the secondary effect of not requiring thread local storage
 // when backtrace support is disabled.
@@ -142,10 +146,6 @@ using CrashHandlerStringStorage =
 static CrashHandlerStringStorage crashHandlerStringStorage;
 #endif
 
-static const char *BugReportMsg =
-    "PLEASE submit a bug report to " BUG_REPORT_URL
-    " and include the crash backtrace.\n";
-
 /// This callback is run if a fatal signal is delivered to the process, it
 /// prints the pretty stack trace.
 static void CrashHandler(void *) {
@@ -203,9 +203,11 @@ static void printForSigInfoIfNeeded() {
 #endif // ENABLE_BACKTRACES
 
 void llvm::setBugReportMsg(const char *Msg) {
-#if ENABLE_BACKTRACES
   BugReportMsg = Msg;
-#endif
+}
+
+const char *llvm::getBugReportMsg() {
+  return BugReportMsg;
 }
 
 PrettyStackTraceEntry::PrettyStackTraceEntry() {