[clang] Put original flags on 'Driver args:' crash report line

We used to put the canonical spelling of flags after alias processing
on that line. For clang-cl in particular, that meant that we put flags
on that line that the clang-cl driver doesn't even accept, and the
"Driver args:" line wasn't usable.

Differential Revision: https://reviews.llvm.org/D110458

clang/lib/Driver/Driver.cpp

@@ -1216,8 +1216,14 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
 
 static void printArgList(raw_ostream &OS, const llvm::opt::ArgList &Args) {
   llvm::opt::ArgStringList ASL;
-  for (const auto *A : Args)
+  for (const auto *A : Args) {
+    // Use user's original spelling of flags. For example, use
+    // `/source-charset:utf-8` instead of `-finput-charset=utf-8` if the user
+    // wrote the former.
+    while (A->getAlias())
+      A = A->getAlias();
     A->render(Args, ASL);
+  }
 
   for (auto I = ASL.begin(), E = ASL.end(); I != E; ++I) {
     if (I != ASL.begin())

clang/test/Driver/crash-report-clang-cl.c

@@ -0,0 +1,24 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+
+// RUN: env TMPDIR=%t TEMP=%t TMP=%t RC_DEBUG_OPTIONS=1           \
+// RUN: not %clang_cl -fsyntax-only /Brepro /source-charset:utf-8 \
+// RUN:     -- %s 2>&1 | FileCheck %s
+// RUN: cat %t/crash-report-*.sh | FileCheck --check-prefix=CHECKSH %s
+
+// REQUIRES: crash-recovery
+
+#pragma clang __debug crash
+
+// CHECK: Preprocessed source(s) and associated run script(s) are located at:
+// CHECK-NEXT: note: diagnostic msg: {{.*}}crash-report-clang-cl-{{.*}}.c
+// CHECKSH: # Crash reproducer
+// CHECKSH-NEXT: # Driver args: {{.*}}"-fsyntax-only"
+// CHECKSH-SAME: /Brepro
+// CHECKSH-SAME: /source-charset:utf-8
+// CHECKSH-NOT: -mno-incremental-linker-compatible
+// CHECKSH-NOT: -finput-charset=utf-8
+// CHECKSH-NEXT: # Original command: {{.*$}}
+// CHECKSH-NEXT: "-cc1"
+// CHECKSH: "-main-file-name" "crash-report-clang-cl.c"
+// CHECKSH: "crash-report-{{[^ ]*}}.c"