From f2f2d1f885d034b26e98fe0d6a9e5a0d97c86bb3 Mon Sep 17 00:00:00 2001
From: Greg Hewgill <greg@hewgill.com>
Date: Fri, 11 Feb 2011 18:51:22 +0100
Subject: [PATCH] Fixed #2571 (Preprocessor: better handling for #undef)

---
 lib/preprocessor.cpp      |  3 ++-
 test/testpreprocessor.cpp | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/lib/preprocessor.cpp b/lib/preprocessor.cpp
index 557fea4fa..638e07b29 100644
--- a/lib/preprocessor.cpp
+++ b/lib/preprocessor.cpp
@@ -1544,7 +1544,8 @@ std::string Preprocessor::getcode(const std::string &filedata, std::string cfg,
             return "";
         }
 
-        if (!match && line.compare(0, 8, "#define ") == 0)
+        if (!match && (line.compare(0, 8, "#define ") == 0 ||
+                       line.compare(0, 6, "#undef") == 0))
         {
             // Remove define that is not part of this configuration
             line = "";
diff --git a/test/testpreprocessor.cpp b/test/testpreprocessor.cpp
index fdeb61d22..09795e370 100644
--- a/test/testpreprocessor.cpp
+++ b/test/testpreprocessor.cpp
@@ -2483,6 +2483,25 @@ private:
             ASSERT_EQUALS("\n\n1\n\n", actual[""]);
             ASSERT_EQUALS(1, (int)actual.size());
         }
+
+        {
+            const char filedata[] = "#define A 1\n"
+                                    "#if 0\n"
+                                    "#undef A\n"
+                                    "#endif\n"
+                                    "A\n";
+
+            // Preprocess => actual result..
+            std::istringstream istr(filedata);
+            std::map<std::string, std::string> actual;
+            Settings settings;
+            Preprocessor preprocessor(&settings, this);
+            preprocessor.preprocess(istr, actual, "file.c");
+
+            // Compare results..
+            ASSERT_EQUALS("\n\n\n\n1\n", actual[""]);
+            ASSERT_EQUALS(1, (int)actual.size());
+        }
     }
 
     void define_ifndef1()