From 16d18724972298c4bf5fb59925649f869118fbac Mon Sep 17 00:00:00 2001
From: Jannick <unknown>
Date: Mon, 28 Aug 2017 17:03:55 +1000
Subject: Bug [#1966]. #define A is treated as #define A 1.

---
 doc/ScintillaHistory.html | 1 +
 lexers/LexCPP.cxx         | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index a645bc066..a6ea45827 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -535,6 +535,7 @@
 	<li>
 	The C++ lexer improved preprocessor conformance.
 	Default value of 0 for undefined preprocessor symbols.
+	#define A is treated as #define A 1.
 	<a href="http://sourceforge.net/p/scintilla/bugs/1966/">Bug #1966</a>.
 	</li>
 	<li>
diff --git a/lexers/LexCPP.cxx b/lexers/LexCPP.cxx
index fbdbd77ca..3fa925b40 100644
--- a/lexers/LexCPP.cxx
+++ b/lexers/LexCPP.cxx
@@ -1333,6 +1333,8 @@ void SCI_METHOD LexerCPP::Lex(Sci_PositionU startPos, Sci_Position length, int i
 									while ((startValue < restOfLine.length()) && IsSpaceOrTab(restOfLine[startValue]))
 										startValue++;
 									std::string value = restOfLine.substr(startValue);
+									if (OnlySpaceOrTab(value))
+										value = "1";	// No value defaults to 1
 									preprocessorDefinitions[key] = value;
 									ppDefineHistory.push_back(PPDefinition(lineCurrent, key, value));
 									definitionsChanged = true;
-- 
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