From a163d0b5de9e268411f51ad28d6ea34bf6e9a88c Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Wed, 25 Jan 2012 06:07:15 +0000
Subject: [PATCH] Fix -fmacro-backtrace-limit=0 to show the entire macro
 backtrace.

llvm-svn: 148930
---
 clang/lib/Frontend/DiagnosticRenderer.cpp |  3 +-
 clang/test/Misc/diag-macro-backtrace.c    | 53 +++++++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/Misc/diag-macro-backtrace.c

diff --git a/clang/lib/Frontend/DiagnosticRenderer.cpp b/clang/lib/Frontend/DiagnosticRenderer.cpp
index 9c4976c2103a..062b8a9d127e 100644
--- a/clang/lib/Frontend/DiagnosticRenderer.cpp
+++ b/clang/lib/Frontend/DiagnosticRenderer.cpp
@@ -260,7 +260,8 @@ void DiagnosticRenderer::emitMacroExpansionsAndCarets(
   Loc = getImmediateMacroCalleeLoc(SM, Loc);
   
   unsigned MacroSkipStart = 0, MacroSkipEnd = 0;
-  if (MacroDepth > DiagOpts.MacroBacktraceLimit) {
+  if (MacroDepth > DiagOpts.MacroBacktraceLimit &&
+      DiagOpts.MacroBacktraceLimit != 0) {
     MacroSkipStart = DiagOpts.MacroBacktraceLimit / 2 +
     DiagOpts.MacroBacktraceLimit % 2;
     MacroSkipEnd = MacroDepth - DiagOpts.MacroBacktraceLimit / 2;
diff --git a/clang/test/Misc/diag-macro-backtrace.c b/clang/test/Misc/diag-macro-backtrace.c
new file mode 100644
index 000000000000..ea40cbec57ed
--- /dev/null
+++ b/clang/test/Misc/diag-macro-backtrace.c
@@ -0,0 +1,53 @@
+// RUN: %clang -fsyntax-only -fmacro-backtrace-limit=0 %s 2>&1 | FileCheck %s
+
+#define FOO 1+"hi" 
+#define BAR FOO
+#define BAZ BAR
+#define QUZ BAZ
+#define TAZ QUZ
+#define ABA TAZ
+#define BAB ABA
+#define ZAZ BAB
+#define WAZ ZAZ
+#define DROOL WAZ
+#define FOOL DROOL
+
+FOOL
+
+// CHECK: :15:1: error: expected identifier or '('
+// CHECK: FOOL
+// CHECK: ^
+// CHECK: :13:14: note: expanded from macro 'FOOL'
+// CHECK: #define FOOL DROOL
+// CHECK:              ^
+// CHECK: :12:15: note: expanded from macro 'DROOL'
+// CHECK: #define DROOL WAZ
+// CHECK:               ^
+// CHECK: :11:13: note: expanded from macro 'WAZ'
+// CHECK: #define WAZ ZAZ
+// CHECK:             ^
+// CHECK: :10:13: note: expanded from macro 'ZAZ'
+// CHECK: #define ZAZ BAB
+// CHECK:             ^
+// CHECK: :9:13: note: expanded from macro 'BAB'
+// CHECK: #define BAB ABA
+// CHECK:             ^
+// CHECK: :8:13: note: expanded from macro 'ABA'
+// CHECK: #define ABA TAZ
+// CHECK:             ^
+// CHECK: :7:13: note: expanded from macro 'TAZ'
+// CHECK: #define TAZ QUZ
+// CHECK:             ^
+// CHECK: :6:13: note: expanded from macro 'QUZ'
+// CHECK: #define QUZ BAZ
+// CHECK:             ^
+// CHECK: :5:13: note: expanded from macro 'BAZ'
+// CHECK: #define BAZ BAR
+// CHECK:             ^
+// CHECK: :4:13: note: expanded from macro 'BAR'
+// CHECK: #define BAR FOO
+// CHECK:             ^
+// CHECK: :3:13: note: expanded from macro 'FOO'
+// CHECK: #define FOO 1+"hi" 
+// CHECK:             ^
+// CHECK: 1 error generated.