Fix unexpected 'unterminated double-quoted sequence' script error

11 files changed, 152 insertions, 54 deletions

diff --git a/libbuild2/build/script/lexer.cxx b/libbuild2/build/script/lexer.cxx
index 5c13239..e0d87fe 100644
--- a/libbuild2/build/script/lexer.cxx
+++ b/libbuild2/build/script/lexer.cxx
@@ -35,10 +35,7 @@ namespace build2
         bool q (true); // quotes
 
         if (!esc)
-        {
-          assert (!state_.empty ());
-          esc = state_.top ().escapes;
-        }
+          esc = current_state ().escapes;
 
         switch (m)
         {
@@ -107,7 +104,7 @@ namespace build2
         }
 
         assert (ps == '\0');
-        state_.push (
+        mode_impl (
           state {m, data, nullopt, false, false, ps, s, n, q, *esc, s1, s2});
       }
 
@@ -116,7 +113,7 @@ namespace build2
       {
         token r;
 
-        switch (state_.top ().mode)
+        switch (mode ())
         {
         case lexer_mode::command_line:
         case lexer_mode::first_token:
@@ -142,7 +139,7 @@ namespace build2
         xchar c (get ());
         uint64_t ln (c.line), cn (c.column);
 
-        state st (state_.top ()); // Make copy (see first/second_token).
+        state st (current_state ()); // Make copy (see first/second_token).
         lexer_mode m (st.mode);
 
         auto make_token = [&sep, ln, cn] (type t)
@@ -158,7 +155,7 @@ namespace build2
           assert (m == lexer_mode::variable_line ||
                   m == lexer_mode::for_loop);
 
-          state_.top ().lsbrace = false; // Note: st is a copy.
+          current_state ().lsbrace = false; // Note: st is a copy.
 
           if (c == '[' && (!st.lsbrace_unsep || !sep))
             return make_token (type::lsbrace);
@@ -171,7 +168,7 @@ namespace build2
         // we push any new mode (e.g., double quote).
         //
         if (m == lexer_mode::first_token || m == lexer_mode::second_token)
-          state_.pop ();
+          expire_mode ();
 
         // NOTE: remember to update mode() if adding new special characters.
 
@@ -182,7 +179,7 @@ namespace build2
             // Expire variable value mode at the end of the line.
             //
             if (m == lexer_mode::variable_line)
-              state_.pop ();
+              expire_mode ();
 
             sep = true; // Treat newline as always separated.
             return make_token (type::newline);
diff --git a/libbuild2/build/script/lexer.hxx b/libbuild2/build/script/lexer.hxx
index 313d80a..3f51493 100644
--- a/libbuild2/build/script/lexer.hxx
+++ b/libbuild2/build/script/lexer.hxx
@@ -68,6 +68,8 @@ namespace build2
         static redirect_aliases_type redirect_aliases;
 
       private:
+        using build2::script::lexer::mode; // Getter.
+
         token
         next_line ();
       };
diff --git a/libbuild2/build/script/parser+diag.test.testscript b/libbuild2/build/script/parser+diag.test.testscript
index 272d10c..a720fe2 100644
--- a/libbuild2/build/script/parser+diag.test.testscript
+++ b/libbuild2/build/script/parser+diag.test.testscript
@@ -45,16 +45,19 @@ $* <<EOI >>EOO
     diag: copy foo
     EOO
 
-  # @@ TMP Enable when the unexpected 'unterminated double-quoted sequence'
-  #        error is fixed.
-  #\
   : quoted
   :
-  $* <<EOI >false
+  $* <<EOI >'diag: foo'
     f = foo
     diag "$f"
     EOI
-  #\
+
+  : quoted-eval
+  :
+  $* <<EOI >'diag: foo'
+    f = foo
+    diag "($f)"
+    EOI
 
   : temp_dir
   :
diff --git a/libbuild2/build/script/parser+for.test.testscript b/libbuild2/build/script/parser+for.test.testscript
index 880b03c..2a9f169 100644
--- a/libbuild2/build/script/parser+for.test.testscript
+++ b/libbuild2/build/script/parser+for.test.testscript
@@ -543,20 +543,20 @@
     buildfile:11:1: error: for: missing variable name
     EOE
 
-    # @@ TMP Enable when the unexpected 'unterminated double-quoted sequence'
-    #    error is fixed.
-    #\
-    : quoted-ops
+    : quoted-opt
     :
     $* <<EOI >>EOO
-    o=-w
+    o = -w
     for "$o" x <'a b'
       cmd $x
     end
+    for "($o)" x <'a b'
+      cmd $x
+    end
     EOI
     for -w x <'a b'
+    for -w x <'a b'
     EOO
-    #\
 
     : untyped
     :
diff --git a/libbuild2/lexer.cxx b/libbuild2/lexer.cxx
index 76c31be..9176422 100644
--- a/libbuild2/lexer.cxx
+++ b/libbuild2/lexer.cxx
@@ -160,13 +160,15 @@ namespace build2
         break;
       }
     case lexer_mode::foreign:
-      assert (data > 1);
-      // Fall through.
+      {
+        assert (ps == '\0' && data > 1);
+        s = false;
+        break;
+      }
     case lexer_mode::single_quoted:
     case lexer_mode::double_quoted:
       {
-        assert (ps == '\0');
-        s = false;
+        assert (false); // Can only be set manually in word().
         break;
       }
     case lexer_mode::variable:
@@ -178,8 +180,49 @@ namespace build2
     default: assert (false); // Unhandled custom mode.
     }
 
-    state_.push (
-      state {m, data, nullopt, lsb, false, ps, s, n, q, *esc, s1, s2});
+    mode_impl (state {m, data, nullopt, lsb, false, ps, s, n, q, *esc, s1, s2});
+  }
+
+  void lexer::
+  mode_impl (state&& s)
+  {
+    // If we are in the double-quoted mode then, unless the new mode is eval
+    // or variable, delay the state switch until the current mode is expired.
+    // Note that we delay by injecting the new state beneath the current
+    // state.
+    //
+    if (!state_.empty ()                                &&
+        state_.top ().mode == lexer_mode::double_quoted &&
+        s.mode != lexer_mode::eval                      &&
+        s.mode != lexer_mode::variable)
+    {
+      state qs (move (state_.top ())); // Save quoted state.
+      state_.top () = move (s);        // Overwrite quoted state with new state.
+      state_.push (move (qs));         // Restore quoted state.
+    }
+    else
+      state_.push (move (s));
+  }
+
+  void lexer::
+  expire_mode ()
+  {
+    // If we are in the double-quoted mode, then delay the state expiration
+    // until the current mode is expired. Note that we delay by overwriting
+    // the being expired state with the current state.
+    //
+    assert (!state_.empty () &&
+            (state_.top ().mode != lexer_mode::double_quoted ||
+             state_.size () > 1));
+
+    if (state_.top ().mode == lexer_mode::double_quoted)
+    {
+      state qs (move (state_.top ())); // Save quoted state.
+      state_.pop ();                   // Pop quoted state.
+      state_.top () = move (qs);       // Expire state, restoring quoted state.
+    }
+    else
+      state_.pop ();
   }
 
   token lexer::
@@ -835,6 +878,13 @@ namespace build2
         //
         if (st.quotes && !done)
         {
+          auto quoted_mode = [this] (lexer_mode m)
+          {
+            state_.push (state {
+              m, 0, nullopt, false, false, '\0', false, true, true,
+              state_.top ().escapes, nullptr, nullptr});
+          };
+
           switch (c)
           {
           case '\'':
@@ -842,7 +892,7 @@ namespace build2
               // Enter the single-quoted mode in case the derived lexer needs
               // to notice this.
               //
-              mode (lexer_mode::single_quoted);
+              quoted_mode (lexer_mode::single_quoted);
 
               switch (qtype)
               {
@@ -881,7 +931,8 @@ namespace build2
             {
               get ();
 
-              mode (lexer_mode::double_quoted);
+              quoted_mode (lexer_mode::double_quoted);
+
               st = state_.top ();
               m = st.mode;
 
diff --git a/libbuild2/lexer.hxx b/libbuild2/lexer.hxx
index 78d35d7..4371206 100644
--- a/libbuild2/lexer.hxx
+++ b/libbuild2/lexer.hxx
@@ -133,10 +133,23 @@ namespace build2
     const path_name&
     name () const {return name_;}
 
-    // Note: sets mode for the next token. The second argument can be used to
-    // specify the pair separator character (if the mode supports pairs). If
-    // escapes is not specified, then inherit the current mode's (though a
-    // mode can also override it).
+    // Set the lexer mode for the next token or delay this until the end of a
+    // double-quoted token sequence is encountered. The second argument can be
+    // used to specify the pair separator character (if the mode supports
+    // pairs). If escapes is not specified, then inherit the current mode's
+    // (though a mode can also override it).
+    //
+    // Note that there is a common parsing pattern of sensing the language
+    // construct kind we are about to parse by reading its first token,
+    // switching to an appropriate lexing mode, and then parsing the rest. The
+    // problem here is that the first token may start the double-quoted token
+    // sequence, turning the lexer into the double-quoted mode. In this case
+    // switching the lexer mode right away would not be a good idea. Thus,
+    // this function delays the mode switch until the end of the double-quoted
+    // sequence is encountered. Note, however, that such a delay only works
+    // properly if the function is called right after the first quoted token
+    // is read (because any subsequent tokens may end up being parsed in a
+    // nested mode such as variable or eval; see mode_impl() for details).
     //
     virtual void
     mode (lexer_mode,
@@ -153,10 +166,12 @@ namespace build2
       state_.top ().lsbrace_unsep = unsep;
     }
 
-    // Expire the current mode early.
+    // Expire the current mode early or delay this until the end of a
+    // double-quoted token sequence is encountered (see mode() for details on
+    // the delay condition and reasoning).
     //
     void
-    expire_mode () {state_.pop ();}
+    expire_mode ();
 
     lexer_mode
     mode () const {return state_.top ().mode;}
@@ -258,6 +273,20 @@ namespace build2
     pair<bool, bool>
     skip_spaces ();
 
+    // Set state for the next token or delay until the end of a double-quoted
+    // token sequence is encountered (see mode() for details on the delay
+    // condition and reasoning).
+    //
+    void
+    mode_impl (state&&);
+
+    state&
+    current_state ()
+    {
+      assert (!state_.empty ());
+      return state_.top ();
+    }
+
     // Diagnostics.
     //
   protected:
@@ -286,11 +315,14 @@ namespace build2
     }
 
     const path_name& name_;
-    std::stack<state> state_;
 
     bool sep_; // True if we skipped spaces in peek().
 
   private:
+    // Use current_state(), mode_impl(), and expire_mode().
+    //
+    std::stack<state> state_;
+
     using base = char_scanner<butl::utf8_validator, 2>;
 
     // Buffer for a get()/peek() potential error.
diff --git a/libbuild2/script/lexer.cxx b/libbuild2/script/lexer.cxx
index 7577149..e13bbdb 100644
--- a/libbuild2/script/lexer.cxx
+++ b/libbuild2/script/lexer.cxx
@@ -24,10 +24,7 @@ namespace build2
       bool q (true); // quotes
 
       if (!esc)
-      {
-        assert (!state_.empty ());
-        esc = state_.top ().escapes;
-      }
+        esc = current_state ().escapes;
 
       switch (m)
       {
@@ -84,7 +81,7 @@ namespace build2
       }
 
       assert (ps == '\0');
-      state_.push (
+      mode_impl (
         state {m, data, nullopt, false, false, ps, s, n, q, *esc, s1, s2});
     }
 
@@ -93,7 +90,7 @@ namespace build2
     {
       token r;
 
-      switch (state_.top ().mode)
+      switch (mode ())
       {
       case lexer_mode::command_expansion:
       case lexer_mode::here_line_single:
@@ -119,7 +116,7 @@ namespace build2
       xchar c (get ());
       uint64_t ln (c.line), cn (c.column);
 
-      const state& st (state_.top ());
+      const state& st (current_state ());
       lexer_mode m (st.mode);
 
       auto make_token = [&sep, &m, ln, cn] (type t)
diff --git a/libbuild2/script/lexer.hxx b/libbuild2/script/lexer.hxx
index dbfdfcc..3cbcc03 100644
--- a/libbuild2/script/lexer.hxx
+++ b/libbuild2/script/lexer.hxx
@@ -112,6 +112,8 @@ namespace build2
       const redirect_aliases_type& redirect_aliases;
 
     protected:
+      using build2::lexer::mode; // Getter.
+
       lexer (istream& is, const path_name& name, uint64_t line,
              const char* escapes,
              bool set_mode,
diff --git a/libbuild2/test/script/lexer.cxx b/libbuild2/test/script/lexer.cxx
index 9475ad4..b470d25 100644
--- a/libbuild2/test/script/lexer.cxx
+++ b/libbuild2/test/script/lexer.cxx
@@ -34,10 +34,7 @@ namespace build2
         bool q (true); // quotes
 
         if (!esc)
-        {
-          assert (!state_.empty ());
-          esc = state_.top ().escapes;
-        }
+          esc = current_state ().escapes;
 
         switch (m)
         {
@@ -113,7 +110,7 @@ namespace build2
         }
 
         assert (ps == '\0');
-        state_.push (
+        mode_impl (
           state {m, data, nullopt, false, false, ps, s, n, q, *esc, s1, s2});
       }
 
@@ -122,7 +119,7 @@ namespace build2
       {
         token r;
 
-        switch (state_.top ().mode)
+        switch (mode ())
         {
         case lexer_mode::command_line:
         case lexer_mode::first_token:
@@ -151,7 +148,7 @@ namespace build2
         xchar c (get ());
         uint64_t ln (c.line), cn (c.column);
 
-        state st (state_.top ()); // Make copy (see first/second_token).
+        state st (current_state ()); // Make copy (see first/second_token).
         lexer_mode m (st.mode);
 
         auto make_token = [&sep, ln, cn] (type t)
@@ -167,7 +164,7 @@ namespace build2
           assert (m == lexer_mode::variable_line ||
                   m == lexer_mode::for_loop);
 
-          state_.top ().lsbrace = false; // Note: st is a copy.
+          current_state ().lsbrace = false; // Note: st is a copy.
 
           if (c == '[' && (!st.lsbrace_unsep || !sep))
             return make_token (type::lsbrace);
@@ -180,7 +177,7 @@ namespace build2
         // we push any new mode (e.g., double quote).
         //
         if (m == lexer_mode::first_token || m == lexer_mode::second_token)
-          state_.pop ();
+          expire_mode ();
 
         // NOTE: remember to update mode() if adding new special characters.
 
@@ -191,7 +188,7 @@ namespace build2
             // Expire variable value mode at the end of the line.
             //
             if (m == lexer_mode::variable_line)
-              state_.pop ();
+              expire_mode ();
 
             sep = true; // Treat newline as always separated.
             return make_token (type::newline);
@@ -322,7 +319,7 @@ namespace build2
         if (c == '\n')
         {
           get ();
-          state_.pop (); // Expire the description mode.
+          expire_mode (); // Expire the description mode.
           return token (type::newline, true, ln, cn, token_printer);
         }
 
diff --git a/libbuild2/test/script/lexer.hxx b/libbuild2/test/script/lexer.hxx
index def269b..993a9db 100644
--- a/libbuild2/test/script/lexer.hxx
+++ b/libbuild2/test/script/lexer.hxx
@@ -68,6 +68,8 @@ namespace build2
         static redirect_aliases_type redirect_aliases;
 
       private:
+        using build2::script::lexer::mode; // Getter.
+
         token
         next_line ();
 
diff --git a/libbuild2/test/script/parser+for.test.testscript b/libbuild2/test/script/parser+for.test.testscript
index 9d70886..5350f28 100644
--- a/libbuild2/test/script/parser+for.test.testscript
+++ b/libbuild2/test/script/parser+for.test.testscript
@@ -801,6 +801,21 @@
     testscript:1:1: error: for: missing variable name
     EOE
 
+    : quoted-opt
+    :
+    $* <<EOI >>EOO
+    o = -w
+    for "$o" x <'a b'
+      cmd $x
+    end;
+    for "($o)" x <'a b'
+      cmd $x
+    end
+    EOI
+    for -w x <'a b'
+    for -w x <'a b'
+    EOO
+
     : untyped
     :
     $* <<EOI >>EOO