Better validate pragma syntax

IWYU pragma: private, include "foo" and
IWYU pragma: no_include "foo" both require quoted includes for their
arguments, but only had assertions to validate.

Add more explicit error messages for invalid syntax in these pragmas.

Fixes issue #365.

2 files changed, 22 insertions, 4 deletions

diff --git a/iwyu_preprocessor.cc b/iwyu_preprocessor.cc
index 46e7718..1251c38 100644
--- a/iwyu_preprocessor.cc
+++ b/iwyu_preprocessor.cc
@@ -230,13 +230,19 @@ void IwyuPreprocessorInfo::HandlePragmaComment(SourceRange comment_range) {
 
   if (MatchTwoTokens(tokens, "private,", "include", 3, begin_loc)) {
     // 3rd token should be a quoted header.
+    const string& suggested = tokens[2];
+    if (!IsQuotedInclude(suggested)) {
+      Warn(begin_loc, "Suggested include must be a quoted header");
+      return;
+    }
+
     const string quoted_this_file
         = ConvertToQuotedInclude(GetFilePath(begin_loc));
-    MutableGlobalIncludePicker()->AddMapping(quoted_this_file, tokens[2]);
+    MutableGlobalIncludePicker()->AddMapping(quoted_this_file, suggested);
     MutableGlobalIncludePicker()->MarkIncludeAsPrivate(quoted_this_file);
     ERRSYM(this_file_entry) << "Adding private pragma-mapping: "
                             << quoted_this_file << " -> "
-                            << tokens[2] << "\n";
+                            << suggested << "\n";
     return;
   }
 
@@ -251,9 +257,15 @@ void IwyuPreprocessorInfo::HandlePragmaComment(SourceRange comment_range) {
 
   if (MatchOneToken(tokens, "no_include", 2, begin_loc)) {
     // 2nd token should be an quoted header.
-    no_include_map_[this_file_entry].insert(tokens[1]);
+    const string& inhibited = tokens[1];
+    if (!IsQuotedInclude(inhibited)) {
+      Warn(begin_loc, "Inhibited include must be a quoted header");
+      return;
+    }
+
+    no_include_map_[this_file_entry].insert(inhibited);
     ERRSYM(this_file_entry) << "Inhibiting include of "
-                            << tokens[1] << "\n";
+                            << inhibited << "\n";
     return;
   }
 
diff --git a/tests/cxx/comment_pragmas-d7.h b/tests/cxx/comment_pragmas-d7.h
index ea5ffdf..df9ebee 100644
--- a/tests/cxx/comment_pragmas-d7.h
+++ b/tests/cxx/comment_pragmas-d7.h
@@ -29,6 +29,12 @@
 // IWYU: Unknown or malformed pragma \(foo\)
 // IWYU pragma: foo
 
+// IWYU: Suggested include must be a quoted header
+// IWYU pragma: private, include not-a-quoted-header.h
+
+// IWYU: Inhibited include must be a quoted header
+// IWYU pragma: no_include not-a-quoted-header.h
+
 // IWYU: begin_exports without an end_exports
 // IWYU pragma: begin_exports