CMake: Clarify the --debug-trycompile help text

2 files changed, 13 insertions, 6 deletions

diff --git a/Source/cmTryCompileCommand.h b/Source/cmTryCompileCommand.h
index 0c67a8b..9923d03 100644
--- a/Source/cmTryCompileCommand.h
+++ b/Source/cmTryCompileCommand.h
@@ -77,14 +77,20 @@ public:
       "Specify COPY_FILE to get a copy of the linked executable at the "
       "given fileName."
       "\n"
-      "In this version all files in bindir/CMakeFiles/CMakeTmp, "
-      "will be cleaned automatically, for debugging a --debug-trycompile can "
-      "be passed to cmake to avoid the clean. Some extra flags that "
-      " can be included are,  "
+      "In this version all files in bindir/CMakeFiles/CMakeTmp "
+      "will be cleaned automatically. For debugging, --debug-trycompile can "
+      "be passed to cmake to avoid this clean. However, multiple sequential "
+      "try_compile operations reuse this single output directory. If you "
+      "use --debug-trycompile, you can only debug one try_compile call at a "
+      "time. The recommended procedure is to configure with cmake all the "
+      "way through once, then delete the cache entry associated with "
+      "the try_compile call of interest, and then re-run cmake again with "
+      "--debug-trycompile."
+      "\n"
+      "Some extra flags that can be included are,  "
       "INCLUDE_DIRECTORIES, LINK_DIRECTORIES, and LINK_LIBRARIES.  "
       "COMPILE_DEFINITIONS are -Ddefinition that will be passed to the "
       "compile line.  "
-
       "try_compile creates a CMakeList.txt "
       "file on the fly that looks like this:\n"
       "  add_definitions( <expanded COMPILE_DEFINITIONS from calling "
diff --git a/Source/cmakemain.cxx b/Source/cmakemain.cxx
index a5dca18..663ce8f 100644
--- a/Source/cmakemain.cxx
+++ b/Source/cmakemain.cxx
@@ -109,7 +109,8 @@ static const char * cmDocumentationOptions[][3] =
    "Dump a wide range of information about the current system. If run "
    "from the top of a binary tree for a CMake project it will dump "
    "additional information such as the cache, log files etc."},
-  {"--debug-trycompile", "Do not delete the try compile directories..",
+  {"--debug-trycompile", "Do not delete the try_compile build tree. Only "
+   "useful on one try_compile at a time.",
    "Do not delete the files and directories created for try_compile calls. "
    "This is useful in debugging failed try_compiles. It may however "
    "change the results of the try-compiles as old junk from a previous "