psql: include intra-query "--" comments in what's sent to the server.

tglsfdc · tglsfdc · commit 83884682f4df · 2021-12-01T12:06:31.000-05:00
psql's lexer has historically deleted dash-dash (single-line) comments from what's collected and sent to the server. This is inconsistent with what it does for slash-star comments, and people have complained before that they wish such comments would be captured in the server log. Undoing the decision completely seems like too big a behavioral change, however. In particular, comments on lines preceding the start of a query are generally not thought of as being part of that query. What we can do to improve the situation is to capture comments that are clearly *within* a query, that is after the first non-whitespace, non-comment token but before the query's ending semicolon or backslash command. This is a nearly trivial code change, and it affects only a few regression test results. (It is tempting to try to apply the same rule to slash-star comments. But it's hard to see how to do that without getting strange history behavior for comments that cross lines, especially if the user then starts a new query on the same line as the star-slash. In view of the lack of complaints, let's leave that case alone.) Discussion: https://postgr.es/m/CAJcOf-cAdMVr7azeYR7nWKsNp7qhORzc84rV6d7m7knG5Hrtsw@mail.gmail.com
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -101,7 +101,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 ------------------------------------------------------------------------------+-------+------
  PREPARE pgss_test (int) AS SELECT $1, $2 LIMIT $3                            |     1 |    1
  SELECT $1                                                                   +|     4 |    4
-                                                                             +|       | 
+   -- multiline                                                              +|       | 
    AS "text"                                                                  |       | 
  SELECT $1 + $2                                                               |     2 |    2
  SELECT $1 + $2 + $3 AS "add"                                                 |     3 |    3
diff --git a/src/fe_utils/psqlscan.l b/src/fe_utils/psqlscan.l
@@ -378,12 +378,11 @@ other			.
 					/*
 					 * Note that the whitespace rule includes both true
 					 * whitespace and single-line ("--" style) comments.
-					 * We suppress whitespace at the start of the query
-					 * buffer.  We also suppress all single-line comments,
-					 * which is pretty dubious but is the historical
-					 * behavior.
+					 * We suppress whitespace until we have collected some
+					 * non-whitespace data.  (This interacts with some
+					 * decisions in MainLoop(); see there for details.)
 					 */
-					if (!(output_buf->len == 0 || yytext[0] == '-'))
+					if (output_buf->len > 0)
 						ECHO;
 				}
 
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
@@ -1905,14 +1905,14 @@ from generate_series(1,5) x,
      (values (0::float8),(0.1),(0.25),(0.4),(0.5),(0.6),(0.75),(0.9),(1)) v(p)
 group by p order by p;
 ERROR:  sum is not an ordered-set aggregate, so it cannot have WITHIN GROUP
-LINE 1: select p, sum() within group (order by x::float8)  
+LINE 1: select p, sum() within group (order by x::float8)  -- error
                   ^
 select p, percentile_cont(p,p)  -- error
 from generate_series(1,5) x,
      (values (0::float8),(0.1),(0.25),(0.4),(0.5),(0.6),(0.75),(0.9),(1)) v(p)
 group by p order by p;
 ERROR:  WITHIN GROUP is required for ordered-set aggregate percentile_cont
-LINE 1: select p, percentile_cont(p,p)  
+LINE 1: select p, percentile_cont(p,p)  -- error
                   ^
 select percentile_cont(0.5) within group (order by b) from aggtest;
  percentile_cont  
diff --git a/src/test/regress/expected/generated.out b/src/test/regress/expected/generated.out
@@ -928,15 +928,15 @@ CREATE TRIGGER gtest2a BEFORE INSERT OR UPDATE ON gtest26
   WHEN (NEW.b < 0)  -- error
   EXECUTE PROCEDURE gtest_trigger_func();
 ERROR:  BEFORE trigger's WHEN condition cannot reference NEW generated columns
-LINE 3:   WHEN (NEW.b < 0)  
+LINE 3:   WHEN (NEW.b < 0)  -- error
                 ^
 DETAIL:  Column "b" is a generated column.
 CREATE TRIGGER gtest2b BEFORE INSERT OR UPDATE ON gtest26
   FOR EACH ROW
   WHEN (NEW.* IS NOT NULL)  -- error
   EXECUTE PROCEDURE gtest_trigger_func();
 ERROR:  BEFORE trigger's WHEN condition cannot reference NEW generated columns
-LINE 3:   WHEN (NEW.* IS NOT NULL)  
+LINE 3:   WHEN (NEW.* IS NOT NULL)  -- error
                 ^
 DETAIL:  A whole-row reference is used and the table contains generated columns.
 CREATE TRIGGER gtest2 BEFORE INSERT ON gtest26
diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
@@ -2100,7 +2100,7 @@ WITH outermost(x) AS (
 )
 SELECT * FROM outermost ORDER BY 1;
 ERROR:  relation "outermost" does not exist
-LINE 4:          SELECT * FROM outermost  
+LINE 4:          SELECT * FROM outermost  -- fail
                                ^
 DETAIL:  There is a WITH item named "outermost", but it cannot be referenced from this part of the query.
 HINT:  Use WITH RECURSIVE, or re-order the WITH items to remove forward references.
@@ -2124,7 +2124,7 @@ WITH RECURSIVE outermost(x) AS (
 )
 SELECT * FROM outermost ORDER BY 1;
 ERROR:  recursive reference to query "outermost" must not appear within a subquery
-LINE 2:   WITH innermost as (SELECT 2 FROM outermost) 
+LINE 2:   WITH innermost as (SELECT 2 FROM outermost) -- fail
                                            ^
 --
 -- This test will fail with the old implementation of PARAM_EXEC parameter

Original file line number	Diff line number	Diff line change
`@@ -2100,7 +2100,7 @@ WITH outermost(x) AS (`
`2100`	`2100`	`)`
`2101`	`2101`	`SELECT * FROM outermost ORDER BY 1;`
`2102`	`2102`	`ERROR: relation "outermost" does not exist`
`2103`		`-LINE 4: SELECT * FROM outermost`
	`2103`	`+LINE 4: SELECT * FROM outermost -- fail`
`2104`	`2104`	`^`
`2105`	`2105`	`DETAIL: There is a WITH item named "outermost", but it cannot be referenced from this part of the query.`
`2106`	`2106`	`HINT: Use WITH RECURSIVE, or re-order the WITH items to remove forward references.`
`@@ -2124,7 +2124,7 @@ WITH RECURSIVE outermost(x) AS (`
`2124`	`2124`	`)`
`2125`	`2125`	`SELECT * FROM outermost ORDER BY 1;`
`2126`	`2126`	`ERROR: recursive reference to query "outermost" must not appear within a subquery`
`2127`		`-LINE 2: WITH innermost as (SELECT 2 FROM outermost)`
	`2127`	`+LINE 2: WITH innermost as (SELECT 2 FROM outermost) -- fail`
`2128`	`2128`	`^`
`2129`	`2129`	`--`
`2130`	`2130`	`-- This test will fail with the old implementation of PARAM_EXEC parameter`