Show warnings when counter variable in FOR loop cannot exceed the constant limit value

e.g. 'for i as ubyte = 0 to 255'

Author: countingpine

src/compiler/error.bas

@@ -86,7 +86,8 @@ declare function hMakeParamDesc _
 		( /'FB_WARNINGMSG_RETURNTYPEMISMATCH        '/ 0, @"Return type mismatch" ), _
 		( /'FB_WARNINGMSG_CALLINGCONVMISMATCH       '/ 0, @"Calling convention mismatch" ), _
 		( /'FB_WARNINGMSG_ARGCNTMISMATCH            '/ 0, @"Argument count mismatch" ), _
-		( /'FB_WARNINGMSG_SUFFIXIGNORED             '/ 1, @"Suffix ignored" ) _
+		( /'FB_WARNINGMSG_SUFFIXIGNORED             '/ 1, @"Suffix ignored" ), _
+		( /'FB_WARNINGMSG_FORENDTOOBIG              '/ 1, @"FOR counter variable is unable to exceed limit value" ) _
 	}
 
 	dim shared errorMsgs( 1 to FB_ERRMSGS-1 ) as const zstring ptr => _

src/compiler/error.bi

@@ -377,6 +377,7 @@ enum FB_WARNINGMSG
 	FB_WARNINGMSG_CALLINGCONVMISMATCH
 	FB_WARNINGMSG_ARGCNTMISMATCH
 	FB_WARNINGMSG_SUFFIXIGNORED
+	FB_WARNINGMSG_FORENDTOOBIG
 
 	FB_WARNINGMSGS
 end enum

src/compiler/parser-compound-for.bas

@@ -834,6 +834,46 @@ sub cForStmtBegin( )
 		hUdtFor( stk )
 	end if
 
+	if( stk->for.end.sym = NULL and stk->for.ispos.sym = NULL ) then
+		dim as integer toobig = 0
+		if ( stk->for.ispos.value.i ) then
+			select case as const typeGetSizeType( stk->for.cnt.dtype )
+			case FB_SIZETYPE_INT8
+				toobig = (stk->for.end.value.i >= 127)
+			case FB_SIZETYPE_UINT8
+				toobig = (stk->for.end.value.i >= 255)
+			case FB_SIZETYPE_INT16
+				toobig = (stk->for.end.value.i >= 32767)
+			case FB_SIZETYPE_UINT16
+				toobig = (stk->for.end.value.i >= 65535)
+			case FB_SIZETYPE_INT32
+				toobig = (stk->for.end.value.i >= 2147483647)
+			case FB_SIZETYPE_UINT32
+				toobig = (stk->for.end.value.i >= 4294967295)
+			case FB_SIZETYPE_INT64
+				toobig = (culngint(stk->for.end.value.i) >= 9223372036854775807)
+			case FB_SIZETYPE_UINT64
+				toobig = (culngint(stk->for.end.value.i) >= 18446744073709551615)
+			end select
+		else
+			select case as const typeGetSizeType( stk->for.cnt.dtype )
+			case FB_SIZETYPE_UINT8, FB_SIZETYPE_UINT16, FB_SIZETYPE_UINT32, FB_SIZETYPE_UINT64
+				toobig = (stk->for.end.value.i <= 0)
+			case FB_SIZETYPE_INT8
+				toobig = (stk->for.end.value.i <= -128)
+			case FB_SIZETYPE_INT16
+				toobig = (stk->for.end.value.i >= -32768)
+			case FB_SIZETYPE_INT32
+				toobig = (stk->for.end.value.i >= -2147483648)
+			case FB_SIZETYPE_INT64
+				toobig = (stk->for.end.value.i >= -9223372036854775808)
+			end select
+		end if
+		if( toobig ) then
+			errReportWarn( FB_WARNINGMSG_FORENDTOOBIG )
+		end if
+	end if
+
 	'' if inic, endc and stepc are all constants,
 	'' check if this branch is needed
 	if( isconst = 3 ) then

tests/warnings/for-limit-too-big.bas

@@ -0,0 +1,16 @@
+#macro testForLimits(T, L, U)
+for i as T = 0 to U
+next i
+for i as T = 0 to L step -1
+next i
+#endmacro
+
+testForLimits(ubyte, 0, 255)
+testForLimits(ushort, 0, 65535)
+testForLimits(ulong, 0, 4294967295)
+testForLimits(ulongint, 0, 18446744073709551615)
+
+testForLimits(byte, -128, 127)
+testForLimits(short, -32768, 32767)
+testForLimits(long, -2147483648, 2147483647)
+testForLimits(longint,   -9223372036854775808, 9223372036854775807)