From d280946474568925016359be742b59fd6c000c52 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Wed, 3 Jun 2020 16:38:23 +0300
Subject: Properly handle diag directive in build script parser

---
 libbuild2/build/script/parser.hxx | 61 ++++++++++++++++++++++++++++++---------
 1 file changed, 48 insertions(+), 13 deletions(-)

(limited to 'libbuild2/build/script/parser.hxx')

diff --git a/libbuild2/build/script/parser.hxx b/libbuild2/build/script/parser.hxx
index 15d4ede..4b98cbc 100644
--- a/libbuild2/build/script/parser.hxx
+++ b/libbuild2/build/script/parser.hxx
@@ -36,7 +36,7 @@ namespace build2
         script
         pre_parse (const target&,
                    istream&, const path_name&, uint64_t line,
-                   optional<string> diag, const location& diag_loc);
+                   optional<string> diag_name, const location& diag_loc);
 
         // Recursive descent parser.
         //
@@ -67,6 +67,16 @@ namespace build2
         execute (const scope& root, const scope& base,
                  environment&, const script&, runner&);
 
+        // Parse a special builtin line into names, performing the variable
+        // and pattern expansions. If omit_builtin is true, then omit the
+        // builtin name from the result.
+        //
+        names
+        execute_special (const scope& root, const scope& base,
+                         environment&,
+                         const line&,
+                         bool omit_builtin = true);
+
       protected:
         void
         exec_script ();
@@ -87,24 +97,28 @@ namespace build2
         // leaving the rest for the base parser to handle.
         //
         // During pre-parsing try to deduce the low-verbosity script
-        // diagnostics name.
+        // diagnostics name as a program/builtin name or obtain the custom
+        // low-verbosity diagnostics specified with the diag builtin. Note
+        // that the diag builtin can only appear at the beginning of the
+        // command line.
         //
         virtual optional<process_path>
-        parse_program (token&, build2::script::token_type&, names&) override;
-
-        void
-        parse_program_diag (token&, build2::script::token_type&, names&);
+        parse_program (token&, build2::script::token_type&,
+                       bool first,
+                       names&) override;
 
       protected:
         script* script_;
 
-        // Current low-verbosity script diagnostics name and weight.
+        // Current low-verbosity script diagnostics and its weight.
         //
         // During pre-parsing each command leading names are translated into a
-        // potential script name, unless it is set manually (with the diag
-        // directive or via the constructor). The potential script name has a
-        // weight associated with it, so script names with greater weights
-        // override names with lesser weights. The possible weights are:
+        // potential low-verbosity script diagnostics name, unless the
+        // diagnostics is set manually (script name via the constructor or
+        // custom diagnostics via the diag builtin). The potential script
+        // name has a weight associated with it, so script names with greater
+        // weights override names with lesser weights. The possible weights
+        // are:
         //
         // 0     - builtins that do not add to the script semantics (exit,
         //         true, etc) and are never picked up as a script name
@@ -119,8 +133,20 @@ namespace build2
         // then this ambiguity is reported unless a higher-weighted name is
         // encountered later.
         //
-        optional<pair<string, location>> diag;
-        optional<pair<string, location>> diag2;
+        // If the diag builtin is encountered, then its whole line is saved
+        // (including the leading 'diag' word) for later execution and the
+        // diagnostics weight is set to 4.
+        //
+        // Any attempt to manually set the custom diagnostics twice (the diag
+        // builtin after the script name or after another diag builtin) is
+        // reported as ambiguity.
+        //
+        // At the end of pre-parsing either diag_name or diag_line (but not
+        // both) are present.
+        //
+        optional<pair<string, location>> diag_name;
+        optional<pair<string, location>> diag_name2; // Ambiguous script name.
+        optional<pair<line, location>>   diag_line;
         uint8_t                          diag_weight = 0;
 
         // True during pre-parsing when the pre-parse mode is temporarily
@@ -128,6 +154,15 @@ namespace build2
         //
         bool pre_parse_suspended_ = false;
 
+        // The alternative location where the next line should be saved.
+        //
+        // It is set to NULL before the script line get parsed, indicating
+        // that the line should by default be appended to the script. However,
+        // parse_program() can point it to a different location where the line
+        // should be saved instead (e.g., diag_line, etc).
+        //
+        line* save_line_;
+
         // Execute state.
         //
         runner* runner_;
-- 
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