[clang] Documentation fixes for LibASTMatchersTutorial

[silvas]

Summary

This patch fixes Bug 25583 as well as cleaning up some other problems in the LibASTMatchersTutorial.

I've updated the tutorial to use:

'./configure.py —bootstrap' rather than 'bootstrap.py' in the ninja buildstep
'ninja check-llvm' and 'ninja check-clang' rather than 'ninja check' and 'ninja clang-test' respectively
Clarified that no output will be produced with the first iteration of the program (Step 1: Create a ClangTool)
Cleaned up some English usage in the section on hasCondition(binaryOperator
Fixed the problem in the original bug report:
'Context->getSourceManager().isFromMainFile(FS->getForLoc()' should be 'Context->getSourceManager().isInMainFile(FS->getForLoc()'

The only change I'm unsure about is changing:

'ninja install' to 'sudo ninja install' in the installation step. If I follow the instructions step-by-step then no special install directory is set and the default is /usr/local on OS X which requires sudo. As we've used sudo in similar circumstances above this then it makes sense to me.

This is my first contribution of any kind to Clang / LLVM (or even open source) so hope I have everything correct.

Thanks,

Simon

[simon.f.whittaker]

Added Manuel Klimek at Sean's suggestion.

[silvas]

Overall this LGTM, but let Manuel or one of the other libTooling folks sign off.

docs/LibASTMatchersTutorial.rst

46

This part is a bit out of date. Ninja is pretty easy to obtain (e.g. from its releases page on github) and CMake has had Ninja support built-in for a while now.

I guess this change doesn't hurt, but (probably in a separate patch) you may want to revamp this whole section on ninja and cmake.

docs/LibASTMatchersTutorial.rst

 aren't built with Ninja support.
 
 .. code-block:: console
 
       cd ~/clang-llvm
       git clone https://github.com/martine/ninja.git
       cd ninja
       git checkout release
-      ./bootstrap.py
+      ./configure.py —bootstrap
       sudo cp ninja /usr/bin/
 
       cd ~/clang-llvm
       git clone git://cmake.org/stage/cmake.git
       cd cmake
       git checkout next
       ./bootstrap
       make
       sudo make install
 
 Okay. Now we'll build Clang!
 
 .. code-block:: console
 
       cd ~/clang-llvm
       mkdir build && cd build
       cmake -G Ninja ../llvm -DLLVM_BUILD_TESTS=ON  # Enable tests; default is off.
       ninja
-      ninja check       # Test LLVM only.
-      ninja clang-test  # Test Clang only.
-      ninja install
+      ninja check-llvm   # Test LLVM only.
+      ninja check-clang  # Test Clang only.
+      sudo ninja install
 
 And we're live.
 
 All of the tests should pass, though there is a (very) small chance that
 you can catch LLVM and Clang out of sync. Running ``'git svn rebase'``
 in both the llvm and clang directories should fix any problems.
 
 Finally, we want to set Clang as its own compiler.
.. code-block:: console
       echo "int main() { return 0; }" > test.cpp
       bin/loop-convert test.cpp --
 
 Note the two dashes after we specify the source file. The additional
 options for the compiler are passed after the dashes rather than loading
 them from a compilation database - there just aren't any options needed
 right now.
 
+As there are no syntax errors in the example no output will be produced.
+
 Intermezzo: Learn AST matcher basics
 ====================================
 
 Clang recently introduced the :doc:`ASTMatcher
 library <LibASTMatchers>` to provide a simple, powerful, and
 concise way to describe specific patterns in the AST. Implemented as a
 DSL powered by macros and templates (see
 `ASTMatchers.h <../doxygen/ASTMatchers_8h_source.html>`_ if you're

 
 .. code-block:: c++
 
       hasCondition(binaryOperator(
         hasOperatorName("<"),
         hasLHS(declRefExpr(to(varDecl(hasType(isInteger()))))),
         hasRHS(expr(hasType(isInteger())))))
 
-Why? Because it doesn't work. Of the three loops provided in
+However this doesn't work, of the three loops provided in
 ``test-files/simple.cpp``, zero of them have a matching condition. A
 quick look at the AST dump of the first for loop, produced by the
-previous iteration of loop-convert, shows us the answer:
+previous iteration of loop-convert, shows us why:
 
 ::
 
       (ForStmt 0x173b240
         (DeclStmt 0x173afc8
           0x173af50 "int i =
             (IntegerLiteral 0x173afa8 'int' 0)")
         <<>>

 And change ``LoopPrinter::run`` to
 
 .. code-block:: c++
 
       void LoopPrinter::run(const MatchFinder::MatchResult &Result) {
         ASTContext *Context = Result.Context;
         const ForStmt *FS = Result.Nodes.getStmtAs<ForStmt>("forLoop");
         // We do not want to convert header files!
-        if (!FS || !Context->getSourceManager().isFromMainFile(FS->getForLoc()))
+        if (!FS || !Context->getSourceManager().isInMainFile(FS->getForLoc()))
           return;
         const VarDecl *IncVar = Result.Nodes.getNodeAs<VarDecl>("incVarName");
         const VarDecl *CondVar = Result.Nodes.getNodeAs<VarDecl>("condVarName");
         const VarDecl *InitVar = Result.Nodes.getNodeAs<VarDecl>("initVarName");
 
         if (!areSameVariable(IncVar, CondVar) || !areSameVariable(IncVar, InitVar))
           return;
         llvm::outs() << "Potential array-based loop discovered.\n";