Avoid consecutive whitespace in rules

2 files changed, 14 insertions, 2 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index a7799b6..62b8052 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -877,7 +877,7 @@ std::string cmLocalGenerator::GetIncludeFlags(
   if ((sep[0] != ' ') && !flags.empty() && flags.back() == sep[0]) {
     flags.back() = ' ';
   }
-  return flags;
+  return cmTrimWhitespace(flags);
 }
 
 void cmLocalGenerator::AddCompileOptions(std::string& flags,
@@ -2396,7 +2396,9 @@ void cmLocalGenerator::AddConfigVariableFlags(std::string& flags,
 void cmLocalGenerator::AppendFlags(std::string& flags,
                                    const std::string& newFlags) const
 {
-  if (!newFlags.empty()) {
+  bool allSpaces = std::all_of(newFlags.begin(), newFlags.end(), cmIsSpace);
+
+  if (!newFlags.empty() && !allSpaces) {
     if (!flags.empty()) {
       flags += " ";
     }
diff --git a/Source/cmRulePlaceholderExpander.cxx b/Source/cmRulePlaceholderExpander.cxx
index 5ab1b3a..99b0d5c 100644
--- a/Source/cmRulePlaceholderExpander.cxx
+++ b/Source/cmRulePlaceholderExpander.cxx
@@ -334,7 +334,17 @@ void cmRulePlaceholderExpander::ExpandRuleVariables(
       std::string replace =
         this->ExpandRuleVariable(outputConverter, var, replaceValues);
       expandedInput += s.substr(pos, start - pos);
+
+      // Prevent consecutive whitespace in the output if the rule variable
+      // expands to an empty string.
+      bool consecutive = replace.empty() && start > 0 && s[start - 1] == ' ' &&
+        end + 1 < s.size() && s[end + 1] == ' ';
+      if (consecutive) {
+        expandedInput.pop_back();
+      }
+
       expandedInput += replace;
+
       // move to next one
       start = s.find('<', start + var.size() + 2);
       pos = end + 1;