Problem: block gas used not set in context (cosmos#252)

Solution:
- fix the way context is updated

baseapp/abci.go

@@ -855,12 +855,20 @@ func (app *BaseApp) internalFinalizeBlock(ctx context.Context, req *abci.Finaliz
 		app.finalizeBlockState.ms = app.finalizeBlockState.ms.SetTracingContext(nil).(storetypes.CacheMultiStore)
 	}
 
-	var blockGasUsed uint64
+	var (
+		blockGasUsed   uint64
+		blockGasWanted uint64
+	)
 	for _, res := range txResults {
 		blockGasUsed += uint64(res.GasUsed)
+		blockGasWanted += uint64(res.GasWanted)
 	}
-	sdkCtx := app.finalizeBlockState.Context().WithBlockGasUsed(blockGasUsed)
-	endBlock, err := app.endBlock(sdkCtx)
+	app.finalizeBlockState.SetContext(
+		app.finalizeBlockState.Context().
+			WithBlockGasUsed(blockGasUsed).
+			WithBlockGasWanted(blockGasWanted),
+	)
+	endBlock, err := app.endBlock(ctx)
 	if err != nil {
 		return nil, err
 	}

types/context.go

@@ -72,6 +72,8 @@ type Context struct {
 	txCount int
 	// sum the gas used by all the transactions in the current block, only accessible by end blocker
 	blockGasUsed uint64
+	// sum the gas wanted by all the transactions in the current block, only accessible by end blocker
+	blockGasWanted uint64
 }
 
 // Proposed rename, not done to avoid API breakage
@@ -104,6 +106,7 @@ func (c Context) TxIndex() int                                  { return c.txInd
 func (c Context) MsgIndex() int                                 { return c.msgIndex }
 func (c Context) TxCount() int                                  { return c.txCount }
 func (c Context) BlockGasUsed() uint64                          { return c.blockGasUsed }
+func (c Context) BlockGasWanted() uint64                        { return c.blockGasWanted }
 
 // BlockHeader returns the header by value.
 func (c Context) BlockHeader() cmtproto.Header {
@@ -354,6 +357,11 @@ func (c Context) WithBlockGasUsed(gasUsed uint64) Context {
 	return c
 }
 
+func (c Context) WithBlockGasWanted(gasWanted uint64) Context {
+	c.blockGasWanted = gasWanted
+	return c
+}
+
 // TODO: remove???
 func (c Context) IsZero() bool {
 	return c.ms == nil