Improve Assert output

If an assertion expression contained a macro, the failed assertion
message would print the expanded macro, which is usually unhelpful and
confusing.  Restructure the Assert macros to not expand any macros
when constructing the failure message.

This also fixes that the existing output for Assert et al. shows
the *inverted* condition, which is also confusing and not how
assertions usually work.

Discussion: https://www.postgresql.org/message-id/flat/6c68efe3-117a-dcc1-73d4-18ba1ec532e2%402ndquadrant.com

1 files changed, 20 insertions, 6 deletions

diff --git a/src/include/c.h b/src/include/c.h
index 2a082afab11..f461628a24e 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -755,7 +755,7 @@ typedef NameData *Name;
 #define Trap(condition, errorType) \
 	do { \
 		if (condition) \
-			ExceptionalCondition(CppAsString(condition), (errorType), \
+			ExceptionalCondition(#condition, (errorType), \
 								 __FILE__, __LINE__); \
 	} while (0)
 
@@ -768,20 +768,34 @@ typedef NameData *Name;
  */
 #define TrapMacro(condition, errorType) \
 	((bool) (! (condition) || \
-			 (ExceptionalCondition(CppAsString(condition), (errorType), \
+			 (ExceptionalCondition(#condition, (errorType), \
 								   __FILE__, __LINE__), 0)))
 
 #define Assert(condition) \
-		Trap(!(condition), "FailedAssertion")
+	do { \
+		if (!(condition)) \
+			ExceptionalCondition(#condition, "FailedAssertion", \
+								 __FILE__, __LINE__); \
+	} while (0)
 
 #define AssertMacro(condition) \
-		((void) TrapMacro(!(condition), "FailedAssertion"))
+	((void) ((condition) || \
+			 (ExceptionalCondition(#condition, "FailedAssertion", \
+								   __FILE__, __LINE__), 0)))
 
 #define AssertArg(condition) \
-		Trap(!(condition), "BadArgument")
+	do { \
+		if (!(condition)) \
+			ExceptionalCondition(#condition, "BadArgument", \
+								 __FILE__, __LINE__); \
+	} while (0)
 
 #define AssertState(condition) \
-		Trap(!(condition), "BadState")
+	do { \
+		if (!(condition)) \
+			ExceptionalCondition(#condition, "BadState", \
+								 __FILE__, __LINE__); \
+	} while (0)
 
 /*
  * Check that `ptr' is `bndr' aligned.