Print line number of cache parse errors (#11109)

Track the line number while parsing `CMakeCache.txt` files and include
it in a parse failure error message.

Source/cmCacheManager.cxx

@@ -64,12 +64,14 @@ bool cmCacheManager::LoadCache(const std::string& path,
   const char *realbuffer;
   std::string buffer;
   std::string entryKey;
+  unsigned int lineno = 0;
   while(fin)
     {
     // Format is key:type=value
     std::string helpString;
     CacheEntry e;
     cmSystemTools::GetLineFromStream(fin, buffer);
+    lineno++;
     realbuffer = buffer.c_str();
     while(*realbuffer != '0' &&
           (*realbuffer == ' ' ||
@@ -77,6 +79,7 @@ bool cmCacheManager::LoadCache(const std::string& path,
            *realbuffer == '\r' ||
            *realbuffer == '\n'))
       {
+      if (*realbuffer == '\n') lineno++;
       realbuffer++;
       }
     // skip blank lines and comment lines
@@ -96,6 +99,7 @@ bool cmCacheManager::LoadCache(const std::string& path,
         helpString += &realbuffer[2];
         }
       cmSystemTools::GetLineFromStream(fin, buffer);
+      lineno++;
       realbuffer = buffer.c_str();
       if(!fin)
         {
@@ -138,8 +142,10 @@ bool cmCacheManager::LoadCache(const std::string& path,
       }
     else
       {
-      cmSystemTools::Error("Parse error in cache file ", cacheFile.c_str(),
+      std::ostringstream error;
-                           ". Offending entry: ", realbuffer);
+      error << "Parse error in cache file " << cacheFile;
+      error << " on line " << lineno << ". Offending entry: " << realbuffer;
+      cmSystemTools::Error(error.str().c_str());
       }
     }
   this->CacheMajorVersion = 0;

Tests/RunCMake/CommandLine/RunCMakeTest.cmake

@@ -33,6 +33,11 @@ run_cmake_command(build-bad-dir
 run_cmake_command(build-bad-generator
   ${CMAKE_COMMAND} --build ${RunCMake_SOURCE_DIR}/cache-bad-generator)
 
+run_cmake_command(cache-bad-entry
+  ${CMAKE_COMMAND} --build ${RunCMake_SOURCE_DIR}/cache-bad-entry/)
+run_cmake_command(cache-empty-entry
+  ${CMAKE_COMMAND} --build ${RunCMake_SOURCE_DIR}/cache-empty-entry/)
+
 function(run_BuildDir)
   # Use a single build tree for a few tests without cleaning.
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/BuildDir-build)

Tests/RunCMake/CommandLine/cache-bad-entry-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/CommandLine/cache-bad-entry-stderr.txt

@@ -0,0 +1 @@
+^CMake Error: Parse error in cache file .*/Tests/RunCMake/CommandLine/cache-bad-entry/CMakeCache.txt on line 7. Offending entry: BAD ENTRY.*

Tests/RunCMake/CommandLine/cache-bad-entry/CMakeCache.txt

@@ -0,0 +1,10 @@
+# This is a comment
+
+// That was an empty line. This isn't.
+EMPTY_LINE:BOOL=FALSE
+
+// Uhoh! Here it comes
+BAD ENTRY
+
+// This is fine
+GOOD_ENTRY:BOOL=TRUE

Tests/RunCMake/CommandLine/cache-empty-entry-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/CommandLine/cache-empty-entry-stderr.txt

@@ -0,0 +1 @@
+^CMake Error: Parse error in cache file .*/Tests/RunCMake/CommandLine/cache-empty-entry/CMakeCache.txt on line 5. Offending entry:.*

Tests/RunCMake/CommandLine/cache-empty-entry/CMakeCache.txt

@@ -0,0 +1,7 @@
+// This is valid
+VALID:BOOL=TRUE
+
+// This isn't
+
+// One final entry
+FINAL:BOOL=TRUE