GenEx: Fix termination bugs in generator expression parser.

Content which is incomplete as a generator expression could cause
segfaults by advancing an iterator beyond end() and dereferencing
it. Such incomplete generator expressions  should be treated as
plain text instead.

Source/cmGeneratorExpressionParser.cxx

@@ -77,6 +77,7 @@ static void extendResult(std::vector<cmGeneratorExpressionEvaluator*> &result,
 void cmGeneratorExpressionParser::ParseGeneratorExpression(
                         std::vector<cmGeneratorExpressionEvaluator*> &result)
 {
+  assert(this->it != this->Tokens.end());
   unsigned int nestedLevel = this->NestingLevel;
   ++this->NestingLevel;
 
@@ -98,7 +99,8 @@ void cmGeneratorExpressionParser::ParseGeneratorExpression(
     // ERROR
     }
 
-  if (this->it->TokenType == cmGeneratorExpressionToken::EndExpression)
+  if (this->it != this->Tokens.end() &&
+      this->it->TokenType == cmGeneratorExpressionToken::EndExpression)
     {
     GeneratorExpressionContent *content = new GeneratorExpressionContent(
                 startToken->Content, this->it->Content
@@ -115,42 +117,50 @@ void cmGeneratorExpressionParser::ParseGeneratorExpression(
   std::vector<std::vector<cmGeneratorExpressionToken>::const_iterator>
                                                             commaTokens;
   std::vector<cmGeneratorExpressionToken>::const_iterator colonToken;
-  if (this->it->TokenType == cmGeneratorExpressionToken::ColonSeparator)
+  if (this->it != this->Tokens.end() &&
+      this->it->TokenType == cmGeneratorExpressionToken::ColonSeparator)
     {
     colonToken = this->it;
     parameters.resize(parameters.size() + 1);
     ++this->it;
-    while (this->it->TokenType == cmGeneratorExpressionToken::CommaSeparator)
+
+    while (this->it != this->Tokens.end() &&
+           this->it->TokenType == cmGeneratorExpressionToken::CommaSeparator)
       {
       commaTokens.push_back(this->it);
       parameters.resize(parameters.size() + 1);
       ++this->it;
       }
-    while (this->it->TokenType == cmGeneratorExpressionToken::ColonSeparator)
+    while (this->it != this->Tokens.end() &&
+           this->it->TokenType == cmGeneratorExpressionToken::ColonSeparator)
       {
       extendText(*(parameters.end() - 1), this->it);
       ++this->it;
       }
-    while(this->it->TokenType != cmGeneratorExpressionToken::EndExpression)
+    while (this->it != this->Tokens.end() &&
+           this->it->TokenType != cmGeneratorExpressionToken::EndExpression)
       {
       this->ParseContent(*(parameters.end() - 1));
-      while (this->it->TokenType == cmGeneratorExpressionToken::CommaSeparator)
+      if (this->it == this->Tokens.end())
+        {
+        break;
+        }
+      while (this->it != this->Tokens.end() &&
+             this->it->TokenType == cmGeneratorExpressionToken::CommaSeparator)
         {
         commaTokens.push_back(this->it);
         parameters.resize(parameters.size() + 1);
         ++this->it;
         }
-      while (this->it->TokenType == cmGeneratorExpressionToken::ColonSeparator)
+      while (this->it != this->Tokens.end() &&
+             this->it->TokenType == cmGeneratorExpressionToken::ColonSeparator)
         {
         extendText(*(parameters.end() - 1), this->it);
         ++this->it;
         }
-      if (this->it == this->Tokens.end())
-        {
-        break;
-        }
       }
-      if(this->it->TokenType == cmGeneratorExpressionToken::EndExpression)
+      if(this->it != this->Tokens.end()
+          && this->it->TokenType == cmGeneratorExpressionToken::EndExpression)
         {
         --this->NestingLevel;
         ++this->it;
@@ -201,6 +211,7 @@ void cmGeneratorExpressionParser::ParseGeneratorExpression(
 void cmGeneratorExpressionParser::ParseContent(
                         std::vector<cmGeneratorExpressionEvaluator*> &result)
 {
+  assert(this->it != this->Tokens.end());
   switch(this->it->TokenType)
     {
     case cmGeneratorExpressionToken::Text:
@@ -245,5 +256,5 @@ void cmGeneratorExpressionParser::ParseContent(
       ++this->it;
       return;
     }
-  // Unreachable. Assert?
+    assert(!"Unhandled token in generator expression.");
 }

Tests/GeneratorExpression/CMakeLists.txt

@@ -49,6 +49,28 @@ add_custom_target(check ALL
     -Dtest_colons_3=$<1:Qt5::Core>
     -Dtest_colons_4=$<1:C:\\CMake>
     -Dtest_colons_5=$<1:C:/CMake>
+    -Dtest_incomplete_1=$<
+    -Dtest_incomplete_2=$<something
+    -Dtest_incomplete_3=$<something:
+    -Dtest_incomplete_4=$<something:,
+    -Dtest_incomplete_5=$something:,>
+    -Dtest_incomplete_6=<something:,>
+    -Dtest_incomplete_7=$<something::
+    -Dtest_incomplete_8=$<something:,
+    -Dtest_incomplete_9=$<something:,,
+    -Dtest_incomplete_10=$<something:,:
+    -Dtest_incomplete_11=$<something,,
+    -Dtest_incomplete_12=$<,,
+    -Dtest_incomplete_13=$<some$<1:special>thing
+    -Dtest_incomplete_14=$<<something
+    -Dtest_incomplete_15=$<some$<thing
+    -Dtest_incomplete_16=$<<some$<thing
+    -Dtest_incomplete_17=$<1:some$thing>
+    -Dtest_incomplete_18=$<1:some,thing
+    -Dtest_incomplete_19=$<1:some,thing$<ANGLE-R>
+    -Dtest_incomplete_20=$<CONFIGURATION$<ANGLE-R>
+    -Dtest_incomplete_21=$<BOOL:something$<ANGLE-R>
+    -Dtest_incomplete_22=$<BOOL:something
     -P ${CMAKE_CURRENT_SOURCE_DIR}/check.cmake
   COMMAND ${CMAKE_COMMAND} -E echo "check done"
   VERBATIM

Tests/GeneratorExpression/check.cmake

@@ -50,3 +50,25 @@ check(test_colons_2 "::")
 check(test_colons_3 "Qt5::Core")
 check(test_colons_4 "C:\\\\CMake")
 check(test_colons_5 "C:/CMake")
+check(test_incomplete_1 "$<")
+check(test_incomplete_2 "$<something")
+check(test_incomplete_3 "$<something:")
+check(test_incomplete_4 "$<something:,")
+check(test_incomplete_5 "$something:,>")
+check(test_incomplete_6 "<something:,>")
+check(test_incomplete_7 "$<something::")
+check(test_incomplete_8 "$<something:,")
+check(test_incomplete_9 "$<something:,,")
+check(test_incomplete_10 "$<something:,:")
+check(test_incomplete_11 "$<something,,")
+check(test_incomplete_12 "$<,,")
+check(test_incomplete_13 "$<somespecialthing")
+check(test_incomplete_14 "$<<something")
+check(test_incomplete_15 "$<some$<thing")
+check(test_incomplete_16 "$<<some$<thing")
+check(test_incomplete_17 "some$thing")
+check(test_incomplete_18 "$<1:some,thing")
+check(test_incomplete_19 "$<1:some,thing>")
+check(test_incomplete_20 "$<CONFIGURATION>")
+check(test_incomplete_21 "$<BOOL:something>")
+check(test_incomplete_22 "$<BOOL:something")