[Driver] Add compiler option to generate a reproducer

One way to currently test the reproducers is to setup
"FORCE_CLANG_DIAGNOSTICS_CRASH=1" before invoking clang. This simulates
a crash and produces the same contents needed by the reproducers.  The
reproducers are specially useful when triaging Modules issues, not only
on crashes, but also for reproducing misleading warnings, errors, etc.

Add a '-gen-reproducer' driver option to clang (or any similar name) and
give users a flag option.

Note that clang already has a -fno-crash-diagnostics, which disables the
crash reproducers. I've decided not to propose "-fcrash-diagnostics"
since it doesn't convey the ideia of reproduction despite a crash.

rdar://problem/24114619

Differential Revision: https://reviews.llvm.org/D27604

llvm-svn: 300109

clang/docs/UsersManual.rst

@@ -562,6 +562,16 @@ control the crash diagnostics.
 The -fno-crash-diagnostics flag can be helpful for speeding the process
 of generating a delta reduced test case.
 
+Clang is also capable of generating preprocessed source file(s) and associated
+run script(s) even without a crash. This is specially useful when trying to
+generate a reproducer for warnings or errors while using modules.
+
+.. option:: -gen-reproducer
+
+  Generates preprocessed source files, a reproducer script and if relevant, a
+  cache containing: built module pcm's and all headers needed to rebuilt the
+  same modules.
+
 .. _rpass:
 
 Options to Emit Optimization Reports

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -94,7 +94,7 @@ def err_drv_compilationdatabase : Error<
 def err_drv_command_signalled : Error<
   "%0 command failed due to signal (use -v to see invocation)">;
 def err_drv_force_crash : Error<
-  "failing because environment variable '%0' is set">;
+  "failing because %select{environment variable 'FORCE_CLANG_DIAGNOSTICS_CRASH' is set|'-gen-reproducer' is used}0">;
 def err_drv_invalid_mfloat_abi : Error<
   "invalid float ABI '%0'">;
 def err_drv_invalid_libcxx_deployment : Error<

clang/include/clang/Driver/Driver.h

@@ -216,6 +216,11 @@ class Driver {
   /// Use lazy precompiled headers for PCH support.
   unsigned CCCUsePCH : 1;
 
+  /// Force clang to emit reproducer for driver invocation. This is enabled
+  /// indirectly by setting FORCE_CLANG_DIAGNOSTICS_CRASH environment variable
+  /// or when using the -gen-reproducer driver flag.
+  unsigned GenReproducer : 1;
+
 private:
   /// Certain options suppress the 'no input files' warning.
   unsigned SuppressMissingInputWarning : 1;

clang/include/clang/Driver/Options.td

@@ -265,6 +265,8 @@ def arcmt_migrate_report_output : Separate<["-"], "arcmt-migrate-report-output">
 def arcmt_migrate_emit_arc_errors : Flag<["-"], "arcmt-migrate-emit-errors">,
   HelpText<"Emit ARC errors even if the migrator can fix them">,
   Flags<[CC1Option]>;
+def gen_reproducer: Flag<["-"], "gen-reproducer">, InternalDebugOpt,
+  HelpText<"Auto-generates preprocessed source files and a reproduction script">;
 
 def _migrate : Flag<["--"], "migrate">, Flags<[DriverOption]>,
   HelpText<"Run the migrator">;
@@ -701,7 +703,8 @@ def fconstexpr_depth_EQ : Joined<["-"], "fconstexpr-depth=">, Group<f_Group>;
 def fconstexpr_steps_EQ : Joined<["-"], "fconstexpr-steps=">, Group<f_Group>;
 def fconstexpr_backtrace_limit_EQ : Joined<["-"], "fconstexpr-backtrace-limit=">,
                                     Group<f_Group>;
-def fno_crash_diagnostics : Flag<["-"], "fno-crash-diagnostics">, Group<f_clang_Group>, Flags<[NoArgumentUnused]>;
+def fno_crash_diagnostics : Flag<["-"], "fno-crash-diagnostics">, Group<f_clang_Group>, Flags<[NoArgumentUnused]>,
+  HelpText<"Disable auto-generation of preprocessed source files and a script for reproduction during a clang crash">;
 def fcreate_profile : Flag<["-"], "fcreate-profile">, Group<f_Group>;
 def fcxx_exceptions: Flag<["-"], "fcxx-exceptions">, Group<f_Group>,
   HelpText<"Enable C++ exceptions">, Flags<[CC1Option]>;

clang/lib/Driver/Driver.cpp

@@ -91,7 +91,7 @@ Driver::Driver(StringRef ClangExecutable, StringRef DefaultTargetTriple,
       CCCPrintBindings(false), CCPrintHeaders(false), CCLogDiagnostics(false),
       CCGenDiagnostics(false), DefaultTargetTriple(DefaultTargetTriple),
       CCCGenericGCCName(""), CheckInputsExist(true), CCCUsePCH(true),
-      SuppressMissingInputWarning(false) {
+      GenReproducer(false), SuppressMissingInputWarning(false) {
 
   // Provide a sane fallback if no VFS is specified.
   if (!this->VFS)
@@ -620,6 +620,9 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
     CCCGenericGCCName = A->getValue();
   CCCUsePCH =
       Args.hasFlag(options::OPT_ccc_pch_is_pch, options::OPT_ccc_pch_is_pth);
+  GenReproducer = Args.hasFlag(options::OPT_gen_reproducer,
+                               options::OPT_fno_crash_diagnostics,
+                               !!::getenv("FORCE_CLANG_DIAGNOSTICS_CRASH"));
   // FIXME: DefaultTargetTriple is used by the target-prefixed calls to as/ld
   // and getToolChain is const.
   if (IsCLMode()) {

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

@@ -3,15 +3,32 @@
 // RUN: mkdir -p %t/i %t/m %t
 
 // RUN: not env FORCE_CLANG_DIAGNOSTICS_CRASH= TMPDIR=%t TEMP=%t TMP=%t \
-// RUN: %clang -fsyntax-only %s -I %S/Inputs/module -isysroot %/t/i/    \
-// RUN: -fmodules -fmodules-cache-path=%t/m/ -DFOO=BAR 2>&1 | FileCheck %s
+// RUN: %clang -fsyntax-only %s \
+// RUN:   -I %S/Inputs/module -isysroot %/t/i/ \
+// RUN:   -fmodules -fmodules-cache-path=%t/m/ -DFOO=BAR 2>&1 | \
+// RUN:   FileCheck -check-prefix=CRASH_ENV %s
+
+// RUN: not env TMPDIR=%t TEMP=%t TMP=%t \
+// RUN: %clang -gen-reproducer -fsyntax-only %s \
+// RUN:   -I %S/Inputs/module -isysroot %/t/i/ \
+// RUN:   -fmodules -fmodules-cache-path=%t/m/ -DFOO=BAR 2>&1 | \
+// RUN:   FileCheck -check-prefix=CRASH_FLAG %s
 
 @import simple;
 const int x = MODULE_MACRO;
 
-// CHECK: Preprocessed source(s) and associated run script(s) are located at:
-// CHECK-NEXT: note: diagnostic msg: {{.*}}.m
-// CHECK-NEXT: note: diagnostic msg: {{.*}}.cache
-// CHECK-NEXT: note: diagnostic msg: {{.*}}.sh
-// CHECK-NEXT: note: diagnostic msg: Crash backtrace is located in
-// CHECK-NEXT: note: diagnostic msg: {{.*}}Library/Logs/DiagnosticReports{{.*}}
+// CRASH_ENV: failing because environment variable 'FORCE_CLANG_DIAGNOSTICS_CRASH' is set
+// 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
+// CRASH_ENV-NEXT: note: diagnostic msg: {{.*}}.sh
+// CRASH_ENV-NEXT: note: diagnostic msg: Crash backtrace is located in
+// CRASH_ENV-NEXT: note: diagnostic msg: {{.*}}Library/Logs/DiagnosticReports{{.*}}
+
+// CRASH_FLAG: failing because '-gen-reproducer' is used
+// CRASH_FLAG: Preprocessed source(s) and associated run script(s) are located at:
+// CRASH_FLAG-NEXT: note: diagnostic msg: {{.*}}.m
+// CRASH_FLAG-NEXT: note: diagnostic msg: {{.*}}.cache
+// CRASH_FLAG-NEXT: note: diagnostic msg: {{.*}}.sh
+// CRASH_FLAG-NEXT: note: diagnostic msg: Crash backtrace is located in
+// CRASH_FLAG-NEXT: note: diagnostic msg: {{.*}}Library/Logs/DiagnosticReports{{.*}}

clang/tools/driver/driver.cpp

@@ -460,8 +460,9 @@ int main(int argc_, const char **argv_) {
     Res = TheDriver.ExecuteCompilation(*C, FailingCommands);
 
   // Force a crash to test the diagnostics.
-  if (::getenv("FORCE_CLANG_DIAGNOSTICS_CRASH")) {
-    Diags.Report(diag::err_drv_force_crash) << "FORCE_CLANG_DIAGNOSTICS_CRASH";
+  if (TheDriver.GenReproducer) {
+    Diags.Report(diag::err_drv_force_crash)
+        << !::getenv("FORCE_CLANG_DIAGNOSTICS_CRASH");
 
     // Pretend that every command failed.
     FailingCommands.clear();