scan-build: Add support of the option --exclude like in scan-build-py

[sylvestre.ledru]

Summary

To exclude thirdparty code.

To test:
With /tmp/foo.c

void test() {
    int x;
    x = 1; // warn
}

$ scan-build --exclude non-existing/  --exclude /tmp/ -v gcc -c foo.c                                                                                                                                                                                   

scan-build: Using '/usr/lib/llvm-7/bin/clang' for static analysis
scan-build: Emitting reports for this run to '/tmp/scan-build-2018-09-16-214531-8410-1'.
foo.c:3:3: warning: Value stored to 'x' is never read
  x = 1; // warn
  ^   ~
1 warning generated.
scan-build: File '/tmp/foo.c' deleted: part of an ignored directory.
scan-build: 0 bugs found.

[sylvestre.ledru]

Fix the indentation

[jroelofs]

LGTM

cfe/trunk/tools/scan-build/bin/scan-build

my %Options = (
   IgnoreErrors => 0,         # Ignore build errors.
   KeepCC => 0,               # Do not override CC and CXX make variables
   ViewResults => 0,          # View results when the build terminates.
   ExitStatusFoundBugs => 0,  # Exit status reflects whether bugs were found
   ShowDescription => 0,      # Display the description of the defect in the list
   KeepEmpty => 0,            # Don't remove output directory even with 0 results.
   EnableCheckers => {},
   DisableCheckers => {},
+  Excludes => [],
   UseCC => undef,            # C compiler to use for compilation.
   UseCXX => undef,           # C++ compiler to use for compilation.
   AnalyzerTarget => undef,
   StoreModel => undef,
   ConstraintsModel => undef,
   InternalStats => undef,
   OutputFormat => "html",
   ConfigOptions => [],       # Options to pass through to the analyzer's -analyzer-config flag.
if (/<!-- BUGTYPE (.*) -->$/) {
       $BugType = $1;
     }
     elsif (/<!-- BUGFILE (.*) -->$/) {
       $BugFile = abs_path($1);
       if (!defined $BugFile) {
          # The file no longer exists: use the original path.
          $BugFile = $1;
       }
+
+      # Get just the path
+      my $p = dirname($BugFile);
+      # Check if the path is found in the list of exclude
+      if (grep { $p =~ m/$_/ } @{$Options{Excludes}}) {
+         if ($Options{Verbose}) {
+             Diag("File '$BugFile' deleted: part of an ignored directory.\n");
+         }
+
+       # File in an ignored directory. Remove it
+       unlink("$Dir/$FName");
+       return;
+      }
+
       UpdatePrefix($BugFile);
     }
     elsif (/<!-- BUGPATHLENGTH (.*) -->$/) {
       $BugPathLength = $1;
     }
     elsif (/<!-- BUGLINE (.*) -->$/) {
       $BugLine = $1;
     }
-plist-html
    outputs the results as a set of HTML and .plist files.
 
  --status-bugs
 
    By default, the exit status of scan-build is the same as the executed build
    command. Specifying this option causes the exit status of scan-build to be 1
    if it found potential bugs and 0 otherwise.
 
+ --exclude <path>
+
+   Do not run static analyzer against files found in this
+   directory (You can specify this option multiple times).
+   Could be useful when project contains 3rd party libraries.
+
  --use-cc [compiler path]
  --use-cc=[compiler path]
 
    scan-build analyzes a project by interposing a "fake compiler", which
    executes a real compiler for compilation and the static analyzer for analysis.
    Because of the current implementation of interposition, scan-build does not
    know what compiler your project normally uses.  Instead, it simply overrides
    the CC environment variable, and guesses your default compiler.
if ($arg eq "-disable-checker") {
       shift @$Args;
       my $Checker = shift @$Args;
       # Store $NumArgs to preserve the order the checkers were disabled.
       $Options{DisableCheckers}{$Checker} = $NumArgs;
       delete $Options{EnableCheckers}{$Checker};
       next;
     }
 
+    if ($arg eq "--exclude") {
+      shift @$Args;
+      my $arg = shift @$Args;
+      # Remove the trailing slash if any
+      $arg =~ s|/$||;
+      push @{$Options{Excludes}}, $arg;
+      next;
+    }
+
     if ($arg eq "-load-plugin") {
       shift @$Args;
       push @{$Options{PluginsToLoad}}, shift @$Args;
       next;
     }
 
     if ($arg eq "--use-analyzer") {
       shift @$Args;